Uham AT CORWEI L UNIVERSITY 924 073 873 279 Cornell University Library The original of tiiis book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924073873279 Production Note Cornell University Library produced this voliame to replace the irreparably deteriorated original. It was scanned using Xerox software and equipment at 600 dots per inch resolution and compressed prior to storage using CCITT Group 4 compression. The digital data were used to create Cornell ' s replacement volume on paper that meets the ANSI Standard Z39. 48-1992. The production of this volume was supported in part by the National Endowment for the Humanities . Digital file copyright by Cornell University Library 1995. Scanned as part of the A.R. Mann Library project to preserve and enhance access to the Core Historical Literature of the Agricultural Sciences. Titles included in this collection are listed in the volumes published by the Cornell University Press in the series THE LITERATURE OF THE AGRICULTURAL SCIENCES, 1991-1995, Wallace C. Olsen, series editor. ^tsitt ^oUegi; 0f Agriculture At (S^arntll University Strata. «. 9. VITAMINES V I T A M I NE S ESSENTIAL POOD FACTORS BT BENJAMIN HARROW, Ph.D. ASSOCIATE IN PHTSIOLOGICAIi CHEMISTRY, COLLEGE OP PHYSICIANS AND SURGEONS, COLUMBIA UNIVEESITY ISTEW YORK E. P. BUTTON &= COlVtPANT 681 FIFTH AVENUE COPYBIQHT, 1921, BY E, P. BUTTON & COMPANY 'AU Bights Ees&rved QP80I V5H3 @ iBise Fiiliited la tlie Vnlted States of Aiaeiloa TO C. S. H. AND M. H. PREFACE This book is a popular presentation of a subject which concerns every one of us; for vitamines are substances, as yet Hi-defined, whose presence in food is essential to our well-being: their absence makes life impossible. And what more pressing problem to-day than that of food! The entire subject is not more than ten years old — ^we ate vitamines before 1910, but we were not aware of it — ^yet the mass of work that has been done during these few years has added enormously to our knowledge of the science of nutrition. But the results of such research work are securely hidden from the gaze of the layman by their publication in technical journals, and through the use of language which is well-nigh meaningless to the man who is not a food special- ist. The aim of the present volume is to reinter- pret, in terms of our everyday tongue, the language of the research worker. Though "popular," the book is, I believe, a very faithful account of the labors of our scientific friends. Experience has taught me that by far the best method of approach to an entirely new subject is the historical or evolutionary. The reasons for each successive step in the process of reasoning viu PREFACE and experimentation then become clear. That is why I have devoted the first part of the book to a survey of nutrition prior to the time when vita- mines were introduced. The summary will, I trust, be found to be a convenient brief review of the entire subject. The bibliography has been prepared to satisfy those readers whose appetites I have whetted. My thanks are due to Professor W. J. Gies (Columbia), Colonel W. P. Chamberlain (Medical Corps, F. S. A.), Dr. Casimir Punk (H. A. Metz & Co.), Dr. Arthur Harden (Lister Institute, London), Professor E. V. McCollum (Johns Hop- kins), Professor L. B. Mendel (Yale), Dr. E. G. Miller, Jr. (Columbia) and Dr. T. B. Osborne (Connecticut Experimental Station). These gen- tlemen have helped me in a number of ways. Professors Gies, Mendel and McCollum, Dr. Funk, Mr. J. E. Whitsit and Mrs. Nellie J. Waller- stein have been kind enough to read the manuscript and to offer many helpful suggestions. My thanks are also due to the British Medical Research Committee and to the editors of the Journal of the American Medical Association, the Philippine Journal of Science and the Carnegie Institute of Washington for their permission to reproduce drawings. Benjamin Habeow. CONTENTS CHAFTBa VAGB I. Introduction , . , 1 II. Caloeiss 5 m. Cakbohtdeates, Fats and Peoteons .... 16 IV. MiNEEAL Matteb 36 v. Watee and Oxtgen 46 VI. Amino-Acids ........ 5S VII. Glycogen oe Animal Staech , .... 83 Vin. Soap and Gltceein 88 IX. VlTAMINES i . 91 X VlTAMINES AND PLANT GEOWTH .... 112 XI. VlTAMINES AND BBEIBEEI 116 Xn. VlTAMINES AND ElCKETS 128 XIIL VlTAMINES AOT) SCfDEVT 137 XIV. VlTAMINES AND PELLAGBA ' 153 XV. SiTMMAaT. Peacticaii Applications . . . 161 Appendix: Table of Compositton and Caloeie Value op the MoEE Impoetant Foods Adopted by the Intee- Allied SciENTinc Food Commission . . . 186 ix CONTENTS PAGE De. Funk's Classification op the Vitamines . 188 Pkb Cent, of 'Amino-Acips Isolated from Vaki- oiTS Proteins 189 The Distribution or Vitamines in the Com- moner Foodstuffs 191 Some Facts Concerning Nutrition, foe the Guidance of Those Engaged in Administra- tion of Food Belief to Famine-Stricken Dis- tricts (British Committee's Eepoet) . . 194 Eefeeences 204 Index . 215 LIST OF CHARTS PAGI ristTBE 1. Growth or an Infant . . . i . 63 " 2. Amino- Acids and Growth . . . ; . 67 " 3. Amino- Acids and Growth ..... 71 " 4. Amino-Acids and Growth ..... 73 " 5. Amino-Acids and Growth 77 " 6. Amino-Aciks and Growth 79 " 7. Absence of Vitamines 93 " 8. A Satisfactort Synthetic Diet . i . 107 VITAMINES VITAMINES OHAPTEE I INTEODUCTION You bum a piece of wood or coal to get heat; but what makes your body hotter than the air outside? Why, when the doctor thrusts a ther- mometer into you, does the instrument register a temperature of 98 — and sometimes a few degrees higher, if you have the "flu" for example — ^though the temperature of the room is much lower? Is your inside an imitation of a fireplace? Even if it is, the source of heat is certainly neither coal, nor wood, nor papef, nor anything else that is commonly used as fuel. Such questions have agitated the minds of think- ing men from the remotest times, but only within the last century or so have satisfactory answers been found. The guess that the body had certain analogies to a furnace was a good one ; but before we could solve the riddle of the body furnace, we had to acquire clearer notions of just what this "burning" is that takes place in the ordinary fire- place. If you want to make a fire you of course have 1 2 VITAMINES to have a fuel. But equally important is the pres- ence of enough air. If your clothes by any accident catch fire, you are warned to throw a wrap tightly around you, so as to prevent access of air. Without air there can be no burning, no matter how much coal or wood there may be. Oxygen. But what is there in the air that is so essential to burning? The chemist tells us that it-^is the oxygen. This gas is present in the air to the extent of about twenty per cent. If a sam- ple of air be taken and the oxygen removed from it, your paper wHl not bum; nor will anything else that ordinarily bums in the air. If, on the other hand, you take your burning paper or lighted candle, and thrust it into a jar containing the removed oxygen, the paper or candle will bum with a brilliancy that dazzles the eye. Priestley, an Englishman, who later took refuge in Pennsylvania to escape from religious persecu- tion, first isolated this wonderful oxygen in 1771, but it remained for Lavoisier, a Frenchman, to show just in what way this gas is related to the process of burning, and to the process of respira- tion or "burning in the body." He did this work while the French Kevolution was doing its work; and he was rewarded for his labors by being guil- lotined. Lavoisier. Lavoisier showed that if you take a piece of coal and bum it, the carbon and the hydrogen, the two chief elements in the coal, com- bine with oxygen, forming carbon dioxide and water respectively; thus INTRODUCTION 3 carbon plus oxygen yields carbon dioxide; and hydrogen plus oxygen yields hydro- gen oxide (commonly known' as water) ; and that as a result of this combination, a large amount of heat is evolved. Lavoisier next showed that much the same thing takes place when food is taken into the body. Here also the carbon and hydrogen in food — ^just as certainly present in meat and bread as in wood and coal — combine with the oxygen in the air ob- tained by breathing, to yield carbon dioxide and water, at the same time liberating heat. That we actually liberate carbon dioxide and water can be easily shown. Take a straw used for drinking a soda and blow through it into a glass containing lime water; the lime water will imme- diately turn milky. The same is true if you thrust a lighted candle into a jar, keep it there for a few seconds, then take it out and add a little lime water to the jar and shake. In either case the chemist can prove to you that it is the carbon di- oxide released from your body or from the lighted candle that turns the lime water mUky. Likewise if you blow on a cold surface, say your glasses, the surface becomes moist. If you bum your candle surrounded by a tall glass chimney, you will notice that the upper portion of the chimney becomes moist; this moisture, to be sure, soon disappears, but that is due to the heat from the candle. Just as heat is produced when the carbon and hydrogen from the candle or coal unite with the 4 VITAMINES oxygen to form carbon dioxide and water, so heat is produced when these elements in the food we eat unite with the oxygen in the air we breathe to produce the same products. Now we know why the doctor's thermometer thrust in your mouth registers a higher tempera- ture than the same thermometer hung in the room. And just as the coal gives the heat and therefore the energy necessary to convert the water in the boiler into steam and so run the engine, so prob- ably the food we take into our system gives us the energy needed to carry on our daily work. Measuring Seat. Obviously enough, the value of the fuel must depend primarily upon the amount of heat you can get out of it. If one ton of coal mined in Pennsylvania gives you one and one-half times as much heat as a ton of coal mined in Wales, — ^if there are more carbon and hydrogen and less impurities in one sample than in an- other — then you will turn to Pennsylvania, for your coal supply; provided, of course, the Welsh coal is not so much cheaper as to offset the in- creased fuel value of the Pennsylvania coal. The question, then, of how much heat you can get out of a ton of coal — or, as the coal merchants and chemists put it, what is the fuel value of one ton of coal — ^becomes of paramount importance. And if the value of the coal lies in the amount of heat you can get out of it, may not the value of food depend upon the amount of heat it produces when "oxidized" in the body? Hence the impor- tance attached to a means for measuring heat. CHAPTER II CALORIES I can buy five pounds of tea from my grocer or a quart of milk from the dairy; but suppose I go to my coal dealer and ask him for one ton of heat? He would probably look me over, then look at his neighbor and point to his forehead. The coal dealer can give me one ton of coal which when burnt gives heat, but neither he nor any other man can sell me one ton of heat as a market com- modity. Why not? Simply because you cannot isolate the heat and keep it. The water may be hot ; the iron may be hot; many things may be; but the heat in all cases is associated with something you can see or touch. You cannot see heat and you cannot touch it. If water is hot, what you see is the water and what you touch is water. If boiling water burns your fingers whereas cold water does not, our scientist friends inform us that in reality the difference between the two states is that in the hot water, the molecules are in more rapid motion than in the cold water. The molecules are in more rapid motion. They run faster. They seem to have more energy. 5 6 VITAMINES Heat indeed is now known to be a form of energy, just as light and electricity are forms of energy. But if so, how are we going to measure this heat? What standard of reference can we adopt by means of which this heat can be meas- ured? In English-speaking countries the yard and the pound are used as standards for measure and weight respectively. What standard of reference can we apply to that which we cannot weigh and cannot measure? Water is the best-known and the most useful liquid. Suppose we take some water and heat it, and while heating it let us thrust a thermometer into the water. The mercury column of the ther- mometer will rise, and whenever this mercury rises we say the temperature is increasing. There seems to be a very simple relationship between the amount of heat the water acquires and the rise of mercury in the thermometer. Why should it not then be possible to measure heat in terms of the rise of the mercury column? Calorie. That is exactly what is done. We take as a standard of reference that amount of heat which is required to raise one kilogram of water one degree centigrade, and we call this the calorie. (The kilogram is approximately equal to about two and one-quarter pounds. The kilogram, based on the metric system, is a standard of weight invariably used in scientific work and very exten- sively used on the continent of Europe. Since the centigrade scale of measuring temperature is based on the metric system, it is used in scientific CALORIES 7 work. One hundred degrees on the centigrade scale are the eqtdvalent of 180 degrees on the Fahrenheit scale. The doctor's thermometer reads degrees Fahrenheit. When he says that your tem- perature is normal, and that it therefore is around 98, he means 98 degrees Fahrenheit. On the cen- tigrade scale this temperature would correspond to about 37.) Calorimeter. Now suppose we take a piece of coal, crush it and weigh one, gram of it (which represents the one-thousandth part of a kilogram), and then put this one gram of coal into a vessel surrounded by another vessel containing one kilo- gram of water, into which a thermometer is in- serted. Let us further suppose that when we bum this coal none of the heat evolved can escape ex- cept by way of the water. The heat the coal evolves in burning will therefore be transmitted to the water, and this transmission of heat will be registered by the thermometer in the water. This thermometer, let us say, will register an increase of seven degrees. The amount of heat evolved by one gram of coal when burnt will therefore be the equivalent of that produced when one kilo- gram of water is heated seven degrees; or it is the equivalent of seven calories. For remember that one calorie represents that amount of heat necessary to raise one kilogram of water one de- gree, and two calories would represent that amount of heat necessary to raise one kilogram of water two degrees; and so on. On the other hand, in- stead of having the weight fixed and the tempera- 8 VITAMINES ture changing, we can reverse the order and have the temperature fixed and the weight changing. For example, one kilogram of water raised seven degrees is the equivalent of seven kilograms of water raised one degree; both are equivalent to seven calories. The calorie is the unit of heat. An arrangement for measuring heat is known as a calorimeter.* Food Valii^s in Terms of Calories. We have seen how Lavoisier had shown that food in the body undergoes much the same change that coal does when it is burnt; in both cases there is a union with oxygen, with the ultimate production of car- bon dioxide and water, and the liberation of heat. The heat formed in the body as a result of the "oxidation" of foods, supplies our energy require- ments.** If this energy is so intimately related to heat production, and if heat is measured in calo- ries, why cannot we measure foods in terms of energy-content, by measuring the number of calo- * The calorie discussed above represents the large calorie. The small calorie is that amount of heat required to raise one gram of water one degree; it is therefore the one-thousandth part of a large calorie. In actual practice the calorimeter consists of a steel bomb, often lined with copper and gold-plated, and a tightly fitting cover with screw collar attachment. A weighed sample to be tested is placed in a capsule within the bomb. The latter is now charged with oxygen under pressure, closed, and immersed in a weighed amount of water. The sample is ignited by means of an electric fuse. The water is constantly stirred and the tempei^ture taien at short intervals by means of a carefully calibrated thermometer, usually reading to one-thousandth of one degree. ** Of course, food has other important functions, not the least of which is to build up or replace cellular tissue, but for our imme- diate purposes in this chapter these need not be considered. CALOEIES 9 ries that a given quantity of food will yield when burnt? A perfectly natural question. Just as we can burn coal and determine the calories liberated, so by suitable means, we can burn any one of the many varieties of food and estimate the calories it produces. In this way we arrive at the conclusion that one food is richer than another because it liberates more calories when burnt; because, in other words, it yields more energy. , To illustrate with an example: The heat value in calories of one pound of corned beef is about 1200 ; that of one pound of tomatoes, 100. Accord- ing to our experiment one pound of beef yields twelve times as much energy as one pound of tomatoes; or, one pound of beef yields as much energy as twelve pounds of tomatoes. The Body Furnace. But now the reader may ask another question: If, as you say, the body in many ways behaves like a furnace, with food serv- ing as fuel, from which heat is produced, why cannot we find out the amount of food or fuel the body uses by measuring the amount of heat it evolves? Why not do to man what we did to a piece of coal or to a portion of food? But you will at once raise the objection that such an experiment would involve the sacrifice of a human being, for you would have to "bum" him up; a phase of the experiment which woidd concern the subject of it even more than the ex- perimenter. On second reflection, however, you 10 yiTAMINES will notice that your objection does not really hold. For in man — in all "things that have the breath of life" — the "furnace" is inside of him. In reality, there are millions and millions of these "furnaces" represented by the millions and millions of cells. The food after careful preparation by the digestive system reaches these cells, is there joined by oxygen from the lungs, and then "oxidized." No light need be applied either to the cells themselves or to the body as a whole. Just how the cells do their "oxidation" work is a mystery which has not yet been solved, though physiologists have a workable hypothesis to explain it. What the cells do we have not been able to repeat in a test tube; which is another way of saying that the mystery of man is man. Let us return. We take our man and put him into a chamber so constructed as to enable us to measure the heat he produces in the course of a day.* We do not have to do to man what we did to coal — apply a light; his cells have their own way of "burning" material without any help from us. We find that this man weighing 160 pounds evolves '2200 calories in twenty-four hours. He receives "square meals" during the day. What deduction may we draw from such an experiment? Obviously enough that the man must have "burnt up" food to the extent of 2200 calories, and that therefore food yielding 2200 calories must be sup- plied to him every day so that he may have the • Those interested in the actual details may consult Sherman : Chemistry of Food and Nutrition, p. 158 (Macmillan Co., 1918). CALORIES 11 necessary energy ; so that he may continue to live. By repeating such an experiment with hundreds of different men, of all sizes and all ages, we can arrive at an "average" figure. Man's Energy Requirements. As a matter of fact, basing such experiments on the weight of the average man — about 160 pounds — the energy re- quirements do amount to about 2200 calories, pro- vided he is resting. There must be great variations in the energy, and therefore food requirements. A man who is sick does not eat as much as a man who is well. A lumberman needs more calories than a clerk; an adult more than a child; a man usually more than a woman. Let us take some concrete cases. Take the aver- age man whUe sleeping. Sleeping does not sus- pend cellular activity. Oxidation of foodstuffs goes on, but not to the same extent as during the day, when the man is active. During every hour's sleep he expends about 65 calories. If he were to sleep twenty-four hours he would expend 1680 calories, but since he is a normal man and sleeps no more than about eight hours, he expends about 520 calories during this period. Let us take it that going and coming from work consumes two hours of the day. Walking is a light form of ex- ercise requiring 170 calories per hour; two hours give us 340 calories. If the man is engaged in manual labor, as a carpenter perhaps, and works the "union" time of eight hours, he will need 240 calories per hour while so engaged ; a total for the 12 VITAMINES eight hours of 1920 calories. Our carpenter has six hours left for recreation — ^for reading news- papers and gossiping and seeing a "movie." We must count the recreation at a hundred calories per hour; a total then for six hours of 600 calories. Adding up our calories for the twenty-four-hour period, we get 520 + 340 + 1920 + 600 = 3380 as the total requirement per working day. You see, this is considerably above the 2200 calories that the average man needs when resting. You may, with Tigerstedt, classify the require- ments by the trade pursued. A shoemaker, he tells us, should thank the Lord when he gets the equiva- lent of 2400 calories, a weaver 2700, a farm laborer 4100, a lumberman over 5000. Womarv's Energy Reqmrements. Women need less. A seamstress rests satisfied — or should rest satisfied — ^with 1800 calories; a bookbinder with 2000; a servant with 2800; a washerwoman with 3200. Remember here that the average weight of woman is less than that of man ; so that in propor- tion to the weight, the woman may receive just as many calories as man.* Children. Children when one year old may need about 1100 calories. The increased require- ments for each succeeding year are — very roughly ■ — about 100 calories. Here again we encounter marked differences between the requirements of boys and those of girls. Where a girl of ten ex- * The phrase "getting so many calories" cannot, of course, be taken literally. From aU that has been said in this chapter, we translate this oft-used expression to mean that amount of food ■which, when oxidized in the body, yields "so many calories." CALOEIES 13 pends 1800 calories, a boy of that age may expend 2300. An Army's Food Reqmrements. The food re- quirements of an army have always been the sub- ject of extremely careful investigation. The fol- lowing figures compiled during the late war are of interest for two reasons: they show the com- paratively high calorific requirement of the Amer- ican soldier (somewhat related to the state of prosperity of the country in which he lives), and the decidedly different requirement of the soldier when in camp and in the field. Training Field American Soldier 3900 calories 4800 calories British " 3400 " 4600 " French " 3300 " 3600 " ItaUau " 2500 " 3300 " Starvation. If a body expends energy, that energy must have a source. The law of conserva- tion of energy teaches us that nothing is created and nothing destroyed, hut things do change. So if the body needs 3000 calories, these have their source in the food taken. But where does the hungry man- — the starving man — get his energy from? The answer to that is that no matter how reckless a man may be in his spending habits, the body is never quite so reckless ; it always stores up a little food for "the rainy day." But this little capital does not last for many days. When the stored food has disappeared, the energy require- ments continue to be met by the "oxidation" of the tissues — the muscle, the fat, the skin, the liver, 14 VITAMINES the blood are used up bit by bit untU the human machine snaps. Most remarkable is the fact that to the very last the brain and heart continue to function with presumably little impairment. They are the last to be attacked. The question is often asked, to what extent does mental work influence calorific needs? No very decided answer to this all-absorbing question can be given. Many experiments have been tried, but the results have been uniformly negative. In one of these experiments Dr. Benedict, of the Carnegie Institute, measured the heat evolved by a num- ber of college students during examination periods. These poor fellows were penned up in calorimeters and their examination questions then set before them. They "sweated blood." When the exams, were over, the same men were put in calorimeters and allowed to rest for a period equivalent to their examination period — three hours — and during this time the heat was measured. No material differ- ence between the two measurements was noticed. However, it may be noticed in passing that Tashiro, a talented Japanese instructor at the Uni- versity of Cincinnati, has shown that when a nerve fiber is stimulated, the carbon dioxide output is increased; which is another way of saying that when the nerves are active, "oxidation" is in- creased, and therefore the calorific needs are greater. Tashiro had devised an apparatus for detecting the minutest traces of carbon dioxide, and it was only with so delicate an instrument that the increased output of carbon dioxide could be CALORIES 15 determined. The amount measured was so small, that it can hardly make any appreciable difference in ordinary metabolic studies. The calorie is a true guide to muscular activity; it seems to be no guide to the activity of the brain. CHAPTER III CAEBOHTDEATES, TATS AND PEOTEESTS We have reached the conclusion that one method of estimating the needs of the body is to ascertain how much heat the body liberates. If we assume that for the average, active individual the heat lib- erated in 24 hours corresponds to 3000 calories, then it becomes perfectly evident that in order to retain our health, we must consume a quantity of food which, when burnt in the body, will give such 3000 calories. From tables that can be found in any book on dietetics (see Appendix) we can find how many calories a pound any of the com- mon foodstuffs will yield when consumed. It be- comes then merely a matter of selecting enough food to give the necessary 3000 calories. The Calorie Is Not the Only Factor Involved. Unfortunately for the simplicity of the science of dietetics, the question of adequate nutrition is a far more complicated one. Calories alone do not completely solve the problem. For take an exam- ple borrowed from our previous chapter. We there stated that one pound of tomatoes represents a fuel value of 100 calories. If your requirements are 3000 calories a day, suppose I were to suggest 16 CARBOHYDRATES, FATS AND PROTEINS 17, to you that you satisfy these requirements by eat- ing 30 pounds of tomatoes? You would laugh at me. You would say you could not do it; it would make you sick. And so it would, despite all as- sertions that your fuel requirements would be satis- fied. You do not object to tomatoes, provided that meat and bread and butter and milk take the place of most of the 30 pounds of tomatoes. Quantity alone is not at all sufficient; quality and variety are equally important. And this brings us to the next step in our subject. Carbohydrates, Fats and Proteins. When the chemist examines the foodstuffs common to man, he finds that he can classify them under three broad divisions: carbohydrates, fats and proteins. There are plenty of differences among the indi- vidual foods in each group, but they show enough common characteristics for them to belong to one family and to be differentiated from foods belong- ing to either of the other families. The fate of different carbohydrates given to the body is much the same. This is true of the fats and proteins. It is much like classifying the people of the world into the white, yellow and black races. The 80 or 90 million white people in America show plenty of differences among themselves; but their color and other anthropological features divide them very sharply from the yellow and black people. • We can best form an idea of these three classes of foodstuffs by naming foods rich in one of the three. Starch and sugar are excellent examples of carbohydrates. Starch is found in abundance 18 VITAMINES in flotir and all cereals, in rice and potatoes. Be- sides the sugar cane and sugar beet, sugar (of sev- eral varieties) is found in milk and fruits. But- ter and the "fat" of meat, and much of cheese and all oils represent the class of fats. Much of the egg and meat and cheese and some of the milk contain proteins. Very few of the common foods contain one hundred per cent of any one of the three classes of foodstuffs; usually each food- stuff consists of various mixtures of two or three of them, as the following table, representing the composition of some common foods, will make clear. (Approximate figures are given. The dif- ference between 100 and the sum of the first three figures in a horizontal column represents — ^rough- ly — the % of water. Mineral salts, though pres- (Per cent) Food Protein Fat Bread (average "white") 9 1 Potatoes 2 0.1 Milk (whole) 4 4 Butter 1 85 Cheese (American pale) 29 36 Oranges 0.8 0.2 Apples 1 0.5 Sugar (eane) Eggs 13 10 Beef (fore, shank, lean) 22 6 Beef (ribs, fat) 15 36 Mutton (leg) 20 12 Veal (breast) 20 11 Fish (mackerel) 19 7 Fish (salmon) 14 8 Peanuts 25 38 Peaa (canned) 4 0.2 Carbohy drate 54 r-) CD u 1200 18 380 5 320 , , 3500 0.3 2000 12 230 3.9 100 100 1800 670 647 1700 860 817 630 580 24 2500 1 252 CARBOHYDRATES, FATS AND PROTEINS Ift ent, and though enormously important, are not included because they will be discussed separately in the next chapter. See particularly page 37 and following.) This table is instructive. You will notice — ^what has already been intimated — ^how all of the com- mon foods are mixtures of two or three of the foodstuffs. Cane sugar and butter are notable ex- ceptions. Tou will notice, furthermore, how rela- tively rich in carbohydrates are bread and potatoes, and how relatively poor in carbohydrates but rich in protein and fat are cheese and eggs and meat and fish. You will notice, if you glance once again at the table, that in the case of milk, though the percentages of fats, carbohydrates and protein are rather small, there is a fairly equal distribution of these three. Now why should milk, the sole food of infants, contain substantial quantities of all three food- stuffs? Why from time immemorial have men selected their food in such a way as to include sub- stantial amounts of the three? There must be some good reason for it. There must be some rea- son why mOk does not contain one hundred per- cent of carbohydrate alone, and why the adult's food does not consist of one hundred percent fat or protein alone. The Function of the Three Glasses of Foodstuffs. As a matter of fact, each class of foodstuff has a very well-defined function. The carbohydrates are primarily energy-formers. Our muscular energy is mainly derived from the carbohydrates we eati •20 VITAMINES It "ia in the course of such musctilar activity that lieat is produced. These carbohydrates, and to a certain extent the fats, have still another important function. We say they "protect" the proteins. This "protection" consists in allowing the protein to attend to its particular business of tissue up-building and re- pair, without having to engage to any large extent in the side line of supplying energy. Within cer- tain limits, the protein can take the place of car- bohydrate as a source of energy, but the carbo- hydrate cannot take the place of protein in building up tissue. We wish then to hamper as little as possible a task which the protein alone can do. Some physiologists are now of the opinion that the proteins' all-important function of tissue up- building is only possible in the presence of carbo- hydrate, and the constant production of sugar (a typical carbohydrate) in diabetes, even though no sugar is supplied to the body, is pointed to in sup- port of the theory. This suggests another ex- tremely important function of carbohydrates. What has been said of carbohydrates is very largely true of fats, with this difference: that on the whole the carbohydrates are more readily "oxi- dized" in the body ; and — and this is the important point — ^the fats act as a reserve supply for the fuel needs of the body. The humps of camels and the fattening of hibernating animals before winter illustrate this property of fats. Your fat is not used until your carbohydrate supply becomes ex- CARBOHYDRATES, FATS AND PROTEINS 21 hausted ; and if you eat more carbohydrate than the immediate needs of the body require, a consider- able portion of the excess will be converted into fat and stored as such. That explains why fat people avoid not only foods rich in fat but also those rich in carbohydrates. The proteins are by far the most important of the three classes of foods, and reasons have already been given for this view. Let us give still an- other. When we analyze living matter — which, unfortunately, can be done only after all life has left the living matter — ^we find that the elements always present are carbon, oxygen, hydrogen and nitrogen. There are also other elements in much smaller proportions, but they need not concern us just yet. When we analyze the food \fe eat we find that the carbohydrates and fats consist of car- bon, hydrogen and oxygen only. To be sure, the proportions of carbon, hydrogen and oxygen vary with the different fats and carbohydrates; but in so far as the elements out of which the fats and carbohydrates are formed are concerned, they are always found to be carbon, hydrogen and oxygen. It is only when we analyze proteins that we dis- cover the other element so essential to life, nitro- gen. Hence the indispensability of proteins. Ton might say, but is not there plenty of free nitrogen in the air, and do we not therefore absorb nitrogen every time we breathe? We do take in nitrogen every time we breathe, but we do not assimilate it; we cannot assimilate nitrogen in the uncomMned state. If you analyze a sample of air •22 VITAMINES before you inhale it and then analyze it after you have exhaled it, you will find that the percentage of nitrogen remains the same; only the percentage of oxygen has changed. Now just as the soU's need for nitrogen cannot be obtained from the nitrogen of the air, but from one of its compounds, such as Chili saltpeter, so the body's need for nitrogen is likewise unobtainable from free nitrogen, but must be supplied by some nitrogen compound, preferably protein. The carbohydrates and fats are the main source of energy of the body. The carbon, hydrogen and oxygen in these substances are changed to carbon dioxide and water, which in their turn consist of carbon, hydrogen and oxygen ; for remember in all chemical changes — ^in all changes — we never create and never destroy, but merely change. If we take sugar into our system (and what is true of sugar is true of fats and carbohydrates in general) the ultimate change that it undergoes may be repre- sented by this equation: C12H22O11 + 12 O2 -^12 002 + IIH2O (sugar) (oxygen) (carb. diox.) (water) (C, carbon; H, hydrogen; O, oxygen) Without attempting to go into the chemistry of such a reaction, without in fact requiring any knowledge of chemistry, you can easUy see for your- self that not only are the same elements present on both sides of the equation, but the same amounts CARBOHYDRATES, FATS AND PROTEINS 2S of these elements. They are in different combina- tions, however. But this equation, like every other chemical equation, fails to show everything about such a reaction. For example, it faUs to tell us that a very considerable amount of heat, measured in calories, is evolved when the sugar and the oxygen combine ; and this heat is the all-important factor in so far as the body is concerned. But the equation fails to answer another ques- tion, of particular consequence just now to the student and philosopher. Extensive researches have shown that fats and carbohydrates are not immediately broken down into carbon dioxide and water; there are a number of intermediate stages. One or two of these intermediate steps have been located, but much of what goes on in the body fac- tory still remains a mystery. Since the proteins also contain carbon, hydrogen and oxygen, besides nitrogen, the first three ele- ments in the protein molecule can be oxidized to^ carbon dioxide and water in much the same way as the fats and carbohydrates, with the consequent Hberation of energy in the form of heat. But pro- teins, as we have already discussed, serve another purpose; and besides, they are more expensive foods than the fats and carbohydrates. And even if, theoretically, there is no reason why a person cannot live on protein alone, provided he takes enough of it, and does not mind the extra expense, experience teaches us that to live on protein alone 24 VITAMINES is not advisable. The ta:s: on the body in having to handle such large quantities of protein is such that, in time, the vitality of the organism is appre- ciably diminished. Minimum Food Bequirements. From what has been said regarding the three classes of foodstuffs, it becomes evident that calories do not represent the sum total of nutritional requirements. Besides a sufficient number of calories, we must have a judicious distribution of these calories in terms of the three classes of foodstuffs. But how much of each must we take? Are there any mimm^um re- quirements of protein, fat and carbohydrate? Taking up the fat and carbohydrate first, as the easier problem to solve, we may state that since both of these serve primarily as sources of energy, the amounts taken per day should be such as to correspond to the energy requirements of the body. If the average man liberates heat in the neighbor- hood of 3000 to 3500 calories per day, he should be given enough fat and carbohydrate to form this amount of heat. Of course, the fact should not be lost sight of that the very constitution of the pro- tein molecule shows it to be an energy-forming as well as a tissue-replacing substance. That means that the amount of fat and carbohydrate eaten need constitute a little less than the equivalent of 3000 to 3500 calories. That means that in order that we may know how much less than 3000 to 3500 calories the fat and carbohydrate need produce, we must first ascertain the minimum protein require- ments of the body. CARBOHYDRATES, FATS AND PROTEINS 25 Instinct a« a Gmde to Man's Food Require- ments. As with all questions relating to food, the earlier experimenters on protein requirement were largely guided by mankind's accumulated experience in the matter. When the average of many thousands of examples was taken, the amount of protein consumed per day by the indi- vidual was a little more than 100 grams. If we take the rough estimate of 30 grams as being the equivalent of one ounce, the hundred grams would be the equivalent of a little more than three ounces. Around this protein requirement of 100 grams per day there have raged battles royal, and the de- cisive test has yet to be made. From the purely economic standpoint this protein requirement be- comes an extremely important one, because the proteins are the most expensive of the three classes of foodstuffs. If then we could, without harm to the population, replace part of the protein by the other two foodstuffs, it would be conferring a bene- fit on the poor part of the population, unless by so doing, our good-natured speculators would come to the rescue of their pockets and demand an in- crease in price for fats and carbohydrates! Some information was shed on the subject of pro- tein requirement by a careful examination of the diet of Asiatics, particularly the Bengalis in India. Their diet is largely vegetarian, and they consume not more than 37 grams of protein per day — about a third of what the European consumes. The Bengalis, it was pointed out, are an inferior race to the Europeans, both physically and mentally, 26 VITAMINES and this inferiority was now largely attributed to deficient protein consumption. This conclusion did not go unchallenged. Sci- entists attempted many quantitative experiments to arrive at some definite results. Unfori;unately for the scientist, the human body, though a mechan- ism in some ways, is still far more than a mechan- ism. What holds true of chemical reactions does not necessarily hold true of body changes. Here there are so many factors over which man has as yet no control ; and even when he realizes some of these factors, they are rarely so well-defined as to stand the test of experiment. Mr. Horace Fletcher. But if scientists per- formed quantitative experiments, there were others, not scientists, who performed what some like to call "common-sense" experiments. A par- ticularly conspicuous individual in this direction was Mr. Horace Fletcher, whom readers of news- papers must remember. Here was a man who had passed middle age and who had been refused life insurance because of delicate health. "Fie upon ye!" cried Fletcher; "there is absolutely nothing the matter with me, except that I eat much too much, and am not careful in what I choose." Whereupon Mr. Fletcher began by cutting down calories and increasing the time taken to masti- cate food. "Fletcherism" became a fad. From our standpoint what is particularly note- worthy in Mr. Fletcher's praiseworthy experiments on himself is the relatively small quantity of pro- tein he consumed. Mr. Fletcher's physique im- CARBOHYDRATES, FATS AND PROTEINS VJi proved decidedly. Fatigue and lameness and colds all disappeared. Naturally enough, Fletcher attrib- uted his success to the adoption of his modified regimen; and in this modified diet, a conspicuous feature was the small amount of protein it con- tained. Nitrogen Equilibrium. There is another way of attacking the problem of protein requirement — a more scientific way. But before we describe this, a few preliminary observations become necessary. The reader will remember what we said above concerning the three classes of foodstuffs, — ^that only the proteins contain the element nitrogen. When we come to trace the course of this protein in the body we find that, in so far as the nitrogen part of the protein is concerned, it is mainly oc- cupied in replacing decayed tissue. Whenever the cell takes up the nitrogen compound to build up tissue, it gives up a corresponding amount of a nitrogen compound which represents the waste material. This waste material finds its way chiefly into the urine. Very small quantities are found in the feces and sweat. Now suppose we determine the amount of nitro- gen in the food we eat, and then determine the amount of nitrogen excreted. If the quantities are approximately equal we say we have reached a "nitrogen equilibrium": the expenditure is equal to the income. All normal, adult people show such a "nitrogen equilibrium." The case is different with growing children. The child grows; the number of his 28 VITAMINES cells multiply; he must therefore keep some of his nitrogen for additions to his little house. Here the nitrogen intake will be greater than the output. Sick men and sick children may serve as the reverse example of the healthy, growing child. Here the tissues may go to waste without any cor- responding replacement. That would mean that the nitrogen eliminated from the body is more than the amount the body receives from its food. Where man has reached the limit of growth and is in a healthy condition, the output and income of nitrogen equal one another. If you give him twice as much protein (and therefore twice as much nitrogen) one week as another, you will soon find that this healthy man will begin to eliminate twice as much nitrogen as he did formerly. The body, you see, does not store protein the way it stores fat. Eat more fat than you can handle, and the extra fat accumulates in your adipose tissue and you become a fat man. (Sometimes you be- come a fat man without eating too much ; but such cases belong to pathology.) Eat more carbohy- drate than the body can handle, and the surplus stock is converted into fat and stored as before. Eat more protein than the body can utilize and the surplus is thrown out. As has already been said, the last statement does not hold true for children. On the face of it you would say that if your adult shows that his nitrogen output and income balance one another — that he is in "nitrogen equi- librium" ; that then he gets all the nitrogen neces- CARBOHYDRATES, FATS AND PROTEINS 29 sary to rebuild waste tissue. He gets what he needs and in sufficient quantity. Now the nitrogen comes from the protein, and the protein alone. Experience has shown that this nitrogen constitutes about 16 per cent of the total protein. This means that we need merely multiply the amount of nitrogen found by the number 6.25 to give us the amount of protein eaten ; for 16 times 6.25 equals 100.* Suppose an extended series of trials on a man show us that when he eats food containing the equivalent of 16 grams of nitrogen per day he also eliminates the equivalent of 16 grams of nitrogen. His balance sheet is clear. He is probably a healthy, normal individual. He is supplied with food in sufficient quantity. These 16 grams of nitrogen in the food show that he must have eaten 16 times 6.25, or 100 grams of protein. So we may arrive at the conclusion that 100 grams of protein are probably necessary for our individual to retain his good health. This will give an idea of how we arrive at a minimum protein require- ment. Now let us take one or two examples to illus- trate this method of investigation. Professor Chittenden's Experiment. Yale men will remember Chittenden, the director of the "Shef." Scientific School. Some years ago Chit- tenden selected a number of instructors, including * The food may also include nitrogen compounds other than protein, but it is unnecessary at this stage to complicate the situa- tion more. so VITAMINES himself, students and army men attached to the hospital corps, and made them the subjects of an experiment in which the amount of protein in the diet was gradually reduced from a little, over 100 grams to 50, and in some cases to 30 grams per day. The loss in energy due to reduction in the protein supply was counterbalanced by increa^ng the quantity 'of fat and carbohydrate, so that the total number of calories remained constant. Even with as low as 30 grams of protein (about one ounce) the "nitrogen equilibrium" was maintained, showing apparently that the health of the subjects was in no way impaired. Chittenden of course drew the obvious conclusion that our protein con- sumption could be cut to one-half without in any way lowering the vitality of the individual. He maintained — ^and here he agreed with Fletcher — that some of the Uls of humanity were due to ex- cessive protein intake; and that therefore the re- duction of the protein in the food eaten also less- ened the possibilities of disease.* Dr. Hindhede. Chittenden's views were sup- ported by Dr. Hindhede, of the Nutrition Labora- tory in Copenhagen ; and during the strenuous days of the late war, when the food of people even in the neutral countries was limited, Hindhede's in- fluence was such that the feeding of the Danish population was left very much in his charge. Objections to a Too Low Protein Diet. From • For further details the reader may consult Dr. Chittenden 's very readable works: Physiological JSeonomy in Nutrition and The Niitrition of Man. Both axe published by rrederick A. Stokes Co. CARBOHYDRATES, FATS AND PROTEINS 31 what has been said, I do not want the reader to get the impression that the problem of protein re- quirement has been definitely solved in favor of the rather low figures of Chittenden and Hindhede. As a matter of fact, the tendency among the most prominent food experts is to retain a figure nearer to 100 grams of protein than 50, as the rations of armies and civilian populations, guided by the ad- vice of such experts, shows (see below). There are one or two important reasons for preferring the older figures. One is that scientific experi- ments are usually of short duration — a few week^ sometimes a few months;* and a diet that may do little harm in the course of a month may do infinite harm if extended over a period of years. This objection can be made to Professor Chitten- den's work, and is, in fact, so general that it can be raised against many of the experiments in nutri- tion, unless animals, such as rats, are employed whose duration of life is considerably shorter than man's; so that months in the life of a rat may correspond to years — and even more — ^in the life of a human being. But here again you may say that what is true of the rat need not necessarily be true of man. Tour point is well taken. The gratifying results obtained in Denmark dur- ing the war by feeding the people little protein diet, as suggested by Dr. Hindhede, look like a victory for those who urge a low protein diet. Un- questionably most of us do eat more protein than * Some of Dr. Hindhede 's experiments are exceptions, for thej lasted from one to two years. 32 VITAMINES is necessary; but the question arises, as we read Dr. Hindhede's paper, whether the decreased mor- tality in Denmark was not to some extent at least due to a decreased alcohol consumption? But there is still another objection against adopting a too low protein standard. The discus- sion in a subsequent chapter will show that what holds true of calories holds true of protein: that just as you may supply the body with all the calo- ries it needs and yet ruin the system if a well-bal- anced selection of the three classes of foodstuffs is not chosen, so you may fulfil protein require- ments and still ruin the body, because the type of protein you have selected is poor in certain very necessary constituents. As the difference between different proteins is largely a matter of the amount of these necessary constituents, it becomes self- evident that 100 grams of protein are more likely to give the necessary amount than 50. You may say, well then if that is the case, why not increase the protein intake even further? Why stop at 100 grams? Why not go on to 200 and 300 grams? The objection to too large quantities . is one mainly of cost. Further, an excess of pro- tein means an excess production of waste products. The drain on the system becomes too great, and the possibilities of a resulting lowered vitality are very much increased. You have then to find the happy medium of satis- fying the protein requirements and yet of not more than satisfying such requirements. If I have gone into the subject of protein require- CARBOHYDRATES, FATS AND PROTEINS S9 ment at some lengtli, it is because so much of the entire subject of dietetics depends upon it ; so much of the health of populations depends upon it. And yet we are still at some distance from a complete solution of the problem. A Satisfactory Diet. Taking into consideration all that has been said, and some other factors that cannot well be discussed in a volume of this kind, experts have adopted the following as a satisfac- tory diet for a healthy man of average weight: protein 100 grams (3.6 ounces), fat 100 grams and carbohydrate 500 grams (18 ounces). The varia- tions for different individuals are quite consider- able, but the example just given may serve as a basis. Experiments have shown that one gram of pro- tein when "oxidized" in the body yields heat to the extent of 4 calories; that one gram of fat under identical conditions wUl yield 9 calories; and one gram of carbohydrate 4 calories. From 100 grams of protein, therefore, we get the equivalent of 100 times 4, or 400 calories; from 100 grams of fat we get 100 times 9, or 900 calories; 500 grams of car- bohydrate give us 500 times 4, or 2000 calories. The total energy value then is 400 plus 900 plus 2000, or 3300 calories. Professor Bayliss gives us the following figures : 100 grams of protein are contained in 18% ounces of steak, 5 pints of mUk, iy2 pounds of oatmeal, 13% ounces of dried meat, or 2% pounds of bread ; 100 grams of fat are contained in 4% ounces of but- ter; 500 grams of carbohydrate are contained in 34 VITAMINES 2 pounds of bread, % pound of oatmeal, lYz pounds of potatoes and one pound of sugar. (See the table in the Appendix. Those of my readers who are interested in the composition of foods and their calorific value may write to the Superinten- dent of Documents, Washington, D. 0., requesting Bulletin 28, Office of Experiment Stations, TJ. S. Department of Agriculture. Enclose 10c. but not in stamps.) Soldiers' Rations. Food experts attached to the armies in the late war had excellent opportunities for studying the nutritional needs of large bodies of men. The war ration adopted by the British for their men in the field was protein 158 grams, fat 200 grams, and carbohydrate 514 grams; a total of 4600 calories. This, you see, is far above that necessary for the average man in peace time, and even above what is necessary for the soldier when in training camp. Our own soldiers when in training received proteiu 139 grams, fat 129 grams and carbohydrate 539 grams; a total of 3980 calo- ries. The following "garrison ration" was the basis for feeding our soldiers in the training camps (the num- bers refer to ounces) : meat 20, beans 2.4, prunes 1.28, sugar 3.2, lard 0.64, syrup 9.32, flour 18, po- tatoes 20, coffee 1.12, mUk 0.5 and butter 0.5. Also small quantities of salt, pepper, cinnamon, vinegar and flavoring extract. "For calculation of the value of the ration," writes Major John R. Murlin, in charge of the food supplies at the training camps, "certain definite substitutions are made. CARBOHYDRATES, FATS AND PROTEINS 35 For example, 70 per cent of the meat component is issued as fresh beef, 20 per cent as ham, and 10 per cent as bacon; 50 per cent of the bean com- ponent is calculated as beans and 50 per cent as rice; TO per cent of the potato component as pota- toes, 20 per cent as onions and 10 per cent as toma- toes, etc. . . . The average value of the ration in the training camp . . . has been in the neighbor- hood of 39 cents per man per day" — a rather mod- est sum when compared with the cost of the ration of the average citizen ! CHAPTER IV MINEEAL MATTER When you bum a piece of coal or paper or wood you always have some ash left. The housewife and the stoker consider the ash nothing but a nuisance. It cannot be burnt and therefore is of no heat value. A relatively large percentage of ash in your coal immediately decreases the value of the fuel. If you bum a piece of meat or any of the com- mon foods, you will also get some ash left. In order to see this ash it will be necessary for you to do a little more burning than the careless house- wife does when she manages to spoil her dinner. The chemist bums such food by placing it in a porceladn receptacle which he calls a crucible, and putting the latter in turn in a muffle which can be heated red hot. In time the charry product gives place to a gray and sometimes almost pure white mass, the color depending upon the variety and quantity of the various mineral constituents in the ash. The operation is now complete. All the black carbon has disappeared. What is left is the "ash." It is material in which the elements sodium and potassium and calcium and phosphorus pre- dominate. The ash is called "inorganic" because 36 MINERAL MATTER 37 it is free from carbon. A substance containing carbon — ^like the meat we started with — ^wotdd be called "organic." Mineral Matter or "Ash" an Essential Part of the Diet. Useless as this ash is to the housewife and stoker, the ash in our food is an indispensable part of the dietary. We could as easily dispense with the protein as we could with the ash, or, as it is sometimes called, the "mineral matter"; and this is merely another way of saying that the ab- sence from the diet of either one of these would soon cause death. Not only then must our calorific requirements be fulfilled; not only must there be a careful dis- tribution of our food in the shape of protein, fat and carbohydrate; but the food must also contain a certain amount of ash or mineral matter. For- tunately, all of our foods contain mineral matter to a greater or less degree ; so that without neces- sitating any particular selection on our part, we usually satisfy the mineral requirement without much difficulty. The Elements in Mineral Matter. When we submit a bundle of cells, consisting of living mat- ter, to chemical analysis, we find that fats, pro- teins and carbohydrates are present in much the same way as in our foods. The general composi- tion of living matter and of the food we eat is much the same. Another type of chemical examination shows us that living matter consists of such ele- ments as carbon, hydrogen, oxygen and nitrogen, again in much the same way as our foods do. In S8 VITAMINES addition, there are smaller quantities of calcium, phosphorus, potassium, sulphur, sodium, chlorine, iron, iodine, etc. Understand that these elements are not present in the free state. You cannot take a piece of protoplasm and point to the iron or chlorine that it contains. No, the iron and the chlorine and all the other elements in the proto- plasm are so combined that they lose their individ- ual properties. Just as our foods must contain carbon, hydro- gen, oxygen and nitrogen not merely to supply the necessary energy, but also to build or rebuild tis- sue, so, in order to build or rebuild tissue, we must supply such elements as calcium, phosphorus, so- dium, etc. ; for these elements just as surely enter into the composition of living matter. It is these elements — calcium, phosphorus, etc. — ^in various chemical combinations, that constitute the ash or mineral matter. I should, of course, qualify my statement some- what when I speak of the composition of living matter. Strictly speaking, we do not know the composition of living matter. Every time we sufe- mit protoplasm to chemical analysis, those familiar properties which in toto manifest themselves to us as "life" disappear. All that we can say is tiiat the probabilities favor the assumption that while the internal arrangements of the molecules in liv- ing matter are different from matter which is no longer "living," the elementary composition of both remains the same. How Mineral Matter Fvmctions. While an im- MINERAL MATTER 39 portant funetion of the mineral matter in diet is to supply certain necessary elements that go to- wards building protoplasmic material, the mineral matter performs other functions equally impor- tant; but most of these are of such a nature as not to be very easily intelligible to the layman. In a general way, it may be stated that these mineral constituents play an important part in regulating the concentration of liquid within and without the cell, and in maintaining the body in a state of neutrality. This last sentence sounds "technical"; but per- haps by amplifying it we can make it less so. Man is made up of millions of cells. These cells are bathed by the lymph and blood which bring food to the cells and carry away the waste material. The cells and blood and lymph may, for our purposes, be considered as liquids in which solids are dis- solved — ^in some such way as the liquid water can dissolve the solid salt. As a matter of fact, physi- co-chemical studies of cells have shown them to be of far more complex structure than the last sen- tence would indicate; but no matter. The cells, you will remember, are pictured as more or less spherical in shape. If the liquid outside the cell contains much dissolved solid as compared to the amount of dissolved solid within the cell, the latter shrinks in size. If the reverse is true — ^if the liquid within the cell contains more dissolved solid than that without — the cell will expand and perhaps burst. In either case we reach an abnormal or pathological condition. It is only when the 40 VITAMINES amoTiiit of dissolved solid within and without the cell is equal, or, to put it better, when the pressure exerted within and without the cell is equal, that normal conditions are retained. The dissolved solids regulate these conditions ; and the particu- lar solids that are largely responsible for this regulatory mechanism are the mineral salts or Body Neutrality. Another function of the min- eral salts, that of maintaining neutrality, also deserves further emphasis. The cells are readily responsive to the slightest disturbances due to out- side influences. Even slight changes in the cells may give rise to profound disturbances in the body. Usually an amount pf acid is formed in the body which might do much harm to the cells and there- fore to the body as a whole. In steps the mineral matter and neutralizes the acids. (It should be mentioned that other substances apart from min- eral matter also show this property.) Of course there are cases where the mineral matter is power- less to do anything. Salt. In some instances some very specific func- tions can be assigned to a number of the constitu- ents of mineral matter, aside from the very general function of the laW;er of contributing to the struc- ture of protoplasm. Salt (the ordinary "table salt") is one of these. When the masticated and somewhat chemically modified food finds its way into the stomach it there undergoes further changes, and one of the two important substances that bring these changes about is hydrochloric MINERAL MATTER 41 acid. This acid, consisting of the two elements, hydrogen and chlorine in chemical union, is not a constituent of any of our foods, and therefore is not taken into our system. In fact, a concentrated solution of it is a decided poison, and a man contemplating suicide would be apt to think of hydrochloric acid as a means to that end. Yet one of the body's branch factories, situated near the lining of the stomach, manufactures a very weak solution of it for the purpose of helping the digestion of food. The Acid in the Stomach. Many theories have been advanced to explain just how the body is capable of producing the hydrochloric acid, but none is very satisfactory. Since the acid consists of hydrogen and chlorine in chemical union, there must be a source of these elements in the body. There is; but just how, beginning with the raw material, we can produce the finished article, is a mystery. The source of the chlorine is salt, which itself consists of the elements sodium and chlorine chemically combined. This contribution to the formation of acid in the stomach is a very impor- tant function of the salt we eat. An Illustration of Chemical Action. It may be of interest, as illustrating just what a chemical action may involve, to say a word or two about the salt. Salt, as we have said, is composed of the two elements sodium and chlorine in chemical com- bination. The chemist gives the name sodium chloride to salt so as to indicate its composition by name. Sodium itself is a lustrous, grayish-white 42 VITAMINES metal, extremely poisonous, and reacts violently with water the minute it comes in contact with the liquid. Students are warned to store their sodium in bottles containing kerosene. They are also warned to handle the metal with forceps and not with the fingers, and to be careful never to bring it in contact with any water, except under carefully regulated conditions. Chlorine, the other constituent of salt, is a light-yellow gas, of suffo- cating odor and very poisonous. Its extensive use on the western front in the earlier days of the war is only too well known to this generation. Yet here are these two elements, the one a poisonous solid and the other a poisonous gas, which can be made to unite with one another to give you sodium chloride or salt, which in appearance does not in the least suggest sodium or chlorine, and which has not only the negative virtue of being non- poisonous, but the positive one of being an abso- lutely indispensable article in our diet. Though salt, like the other mineral constituents, is present in the foods we eat, it is one of the very few that we deliberately add to the diet. We use it and say that it gives flavor to the food. So it does. But you see now that its function is not limited to that of a mere condiment. Calcmm and Phosphorus. The skeleton of bone largely consists of a substance to which chemists give the name calcium phosphate, which, judging by its name, evidently contains calcium and phos- phorus. Here, then, we can point to a very im- portant function of these two elements; We may MINERAL MATTER 43 add one or two others. If you cut yourself so that blood comes to the surface of the skin, why does blood continue to flow only a little while and then stops altogether? (I am here ignoring very serious injury.) You will notice, if you have the courage to watch nature's operation closely enough, that the blood eventually forms a clot and so fills up the leak. This clotting or "coagulation" of the blood would be impossible but for the calcium pres- ent. To be sure, clotting is a process that involves more than the participation of calcium, but this element is necessary. A number of very complicated substances — the phosphatids — are found in larger quantities in the brain than in other parts of the body. Though we do not know just what the phosphatids do, the mere fact that they are present points to a prob- able function; but the fact that they are in such abundance in brain tissue particularly, implies that a phase or phases of brain activity may be asso- ciated with their presence. The name phosphatid will possibly suggest to the reader that it is de- rived from the phosphorus it contains. Phospha- tids do contain phosphorus. "Phosphorus for the Brain." Since phospha- tids contain phosphorus, and since phosphatids are present in large amounts in the brain, it was some- what natural to assume that by increasing the amount of phosphorus in the food, mental develop- ment might be influenced, possibly accelerated. All experiments in this direction have failed to confirm such an assumption. Nevertheless, the 44 VITAMINES idea was sufficiently attractive to quacks and their advertising agents for them to seize upon it and create the slogan "phosphorus for the brain." Phosphorus is essential; a certain minimum quantity must be present; but it does not neces- sarily follow that a surplus over the minimum can be used to advantage. When we speak of phosphorus as being an es- tential in diet we do not mean the element in the free state. We never do mean the elements in the free state. Phosphorus is a poison. "Phosphorus poisoning" is quite common in match factories. But just as carbon is essential not in the form of coal, but in the form of some "food" containing it "in chemical combination," so phosphorus is util- ized only when presented in "chemical combina- tion" with other elements. Oxygen is the only element in the free state that is utilized by the body. Iron is another essential constituent of the diet. It is needed to supply the iron present in hemo- globin, the red pigment of the blood. "Eat iron and you will be strong" — another one of those pieces of advice offered by quacks to credulous peo- ple. If you are anemic, iron in the form of one of its compounds, particularly such as are found in our foods, may be of some benefit ; but far more important is to readjust your manner of living. A wholesome diet, plenty of sleep and plenty of fresh air, will do more to rebuild your red-blood cells than any of the iron tonics that have ever been invented. MINERAL MATTER 45 A Comparison of the Behavior in the Body of Mineral Matter and the Organic Foodstuffs. A feature which sharply distinguishes the behavior of mineral matter from that of fat, carbohydrate and protein, is that the former undergoes no change prior to absorption by the blood. Your salt, for example, passes from the mouth to the stomach, and then into the intestine, and is there absorbed through the walls of the intestine, finding its way directly into the blood stream — the blood in turn carrying the salt to the various tissues of the body. The fat, protein and carbohydrate, however, under- go extensive alterations before the blood gets hold of them. The process of digestion is the process of converting the fats, proteins and carbohydrates into such a state as to make them fit for absorp- tion by the blood. When you suffer from indi- gestion, that usually means that the workmen in the digestive tract — ^known as "enzymes" — respon- sible for the preparation of the foods in a form capable of assimilation by the blood, are either sick in bed, or too tired because of twelve-hour shifts (due to excessive eating), or are out on strike because of low wages (perhaps due to underfeed- ing)- CHAPTER V WATER AND OXYGEN Water. The struggles in life are largely strug- gles to satisfy part of our food requirements. The other part the slum dweller gets as easily as the owner of a Fifth Avenue mansion. That "other part" is water. Perhaps some day our food specu- lators will have studied the science of nutrition sufficiently to realize that water is as much a food as meat and butter and eggs; then they will tax their ingenuity to devise a means by which the production of this valuable liquid can be con- trolled, or its output restricted. But I must not put the speculator on this scent. Abundant in quantity, and reaching the con- sumer at little or no cost, few of us ever include water in our list of foods; yet it is common knowl- edge that you can forgo eating longer than yon can drinking. Water does not undergo any such changes in the digestive tract as do fats, proteins and carbohydrates; it is in fact absorbed and as- similated by the system without any change — like salt ; and like the latter, yields no available energy. Its extreme importance arises from two facts: in the first place, a large percentage of living matter 46 WATER AND OXYGEN 47 consists of water; secondly, the various phases of cellular activity require water as a medium. We are told that "all physiological actions have their seat in systems containing water as an essential element" ; which, translated into our everyday lan- guage, means that life would be impossible without water. Thales, the ancient Greek philosopher, appreciated this when he formulated his system of philosophy in which water was made the origin of all things. Even our good friend Aristotle made water one of the cardinal points of his ^stem of the universe. It is only in our own day that our indifference to the liquid has become so apparent, and that in place of it we have come to worship the cocktail, which, nevertheless, may contain over 90 per cent of water. Our water requirement we get in several ways. Plebeians get it largely from water direct. Almost all of us get some, and many of us get most of our water from beverages. But all of our solid foods contain water. Some, such as fruit and many vegetables, may contain as much as 80 to 90 per cent of the liquid. That is why the calorific ex- pert claims that you do not get your money's worth by eating fruits and vegetables. Our later chap- ters will show that the calorific expert will need to revise some of his opinions. Oxygen. In our discussion of calories, we em- phasized that our source of energy arises from the burning (or combustion, or oxidation) of foods in our system. This burning, as was pointed out, is impossible without the presence of oxygen (or 48 VITAMINES air, which contains oxygen), just as oxygen is needed to bum a candle. If by a food we mean a substance which supplies or helps to supply energy, or one which repairs the waste of tissues and provides raw material for growth, or a substance which serves both these functions, then oxygen is most certainly a food. Absorbed by the lungs from the air and taken up by the red blood cells in the blood, the oxygen is distributed to the cells of the body, and there the oxidations take place. The consequences of a lack of oxygen supply are soon apparent. Sometimes the individual may be surrounded by plenty of air, but his bodily machin- ery may be in such poor condition that he finds it difficult to assimilate the necessary supply. The disease known as asthma may serve as an example. Sometimes again the supply of air may be limited. Again a gas may be present in the air of which the red blood cells may be fonder than of oxygen. Cases of asphyxiation come under this heading. Here one of the products of the incomplete burn- ing of coal in the stove, carbon monoxide, fills the room and finally enters our blood, which seems to have a greater "affinity" for it than for oxygen. But carbon monoxide cannot substitute for oxygen in the burning of foods; so death results. "Fresh" Air. Since the need for "air" is pri- marily our need for oxygen, the question arises, why the desire for fresh air? Does such air con- tain more oxygen than the air of a well-ventilated room? That cannot be, for the percentage of oxy- WATER AND OXYGEN 49 gen in each is the same. Have the other constitu- ents of the air an influence? No doubt, but the most careful chemical and bacteriological analysis fails to distinguish the air outside from the air in a well-ventOated apartment. "A partial explana- tion" [of the obviously beneficial effects of fresh air] , writes Professor Bayliss, "may be, as Leonard Hill contends, that the effect [in a room] is due to the absence of currents of air and the stimulation of the skin produced by them. It would thus be a result of failure of stimulation of the nervous system. The general experience of more refresh- ing sleep obtained when the bedroom window is open tends to support the view of the importance of the effect on the nervous system. The benefit of a 'cold bath' is probably of a similar nature, as is also that of 'exercise' to a certain extent.^' Condiments, Flavors and StimuloMts. Look in- to a rotisserie window and notice how "it makes your mouth water." Making "your mouth water" is a fact, not a fiction. Psychical influences in stimulating digestion are extremely important, as innumerable experiments have shown. These psychical influences may stimulate digestion by stimulating the secretion of digestive juices — the fluids responsible for so altering the food as to make it fit for absorption by the blood and the sys- tem as a whole. Often enough we get no psychical reaction after surveying the dishes spread on the table. Pot roast may not be a relishing dish to some. To make it more so we may do one of several things. 50 VITAMINES jWe may add a little mustard or a little ketcHup to our pot roast ; or we may eat it with some pick- les; or we may add some salt and pepper. Per- haps none of these additions serves the purpose. If so, another dish has to be substituted. But very often the mustard or pickles, etc., do help. Any one of these additional substances helps to do what the mere looking at an appetizing dish will do — ^increase the flow of digestive juices. The primary function of these flavors and condiments is to make the food more appetizing. Slightly removed from the substances just de- scribed are the stimulants, of which tea, coffee/ cocoa, meat extracts (beef tea, beef juice, etc.), and, above all, alcohol are examples. They too — particularly alcohol — stimulate the flow of the digestive juices. With some of them, as with tea and coffee, the stimulation is due to the presence of an alkaloid, and alkaloids are distinctly injuri- ous when taken in large quantities; hence the ad- visability of moderate tea and coffee drinking. Very few of these substances add much to our calorific needs or to our requirements for tissue repair; though cocoa, with its relatively large quantity of sugar and fat (in the milk), and beer do give appreciable energy values. But notice that the calories are not derived to any extent from the stimulant itself, but from the substances mixed with the stimulant or condiment. Alcohol. The best known, the best hated and the best loved stimulant is alcohol (the "grain" or drinking alcohol as distinguished from the wood WATER AND OXYGEN 51 alcohol). Some who see in alcohol only a sub- stance which has been invented to curse mankind, refuse to include it in a list of stimulants; and the weight of much medical authority favors such an exclusion. On the other hand, in diseases such as pneumonia, its beneficial effect has been amply proved. But that, say its opponents, can be said of all medicines; for they all help in small doses and injure in large. , , A small amount of whiskey or a couple of glasses of beer a day have not been shown to have any evil effects on the normal, healthy individual. You may argue that this is merely a negative virtue. But the moderate drinker claims more for his al- cohol. He insists that it serves as an excellent appetizer, and his experience leads him to contra- dict some of the learned doctors. He tells you that the little alcohol he consumes gives him an optimistic view of life, which not all the bungling of politicians can destroy. The case is quite different witH excessive alcohol consumption. Here the facts point to but one conclusion : alcohol in excess is a poison. Autopsy examinations have proved this beyond the shadow of a doubt. You may find impairment of the stomach, of the heart, and above all, of the nervous system. But why wait for these discoveries until death overtakes the sufferer? The results of ex- cessive alcohol consumption on the individual while still alive are only too obvious to the onlooker. CHAPTER VI AMINO-ACIDS Having surveyed rather rapidly the various sub- stances that function as foods; having shown that the calorific value gives incomplete information; having shown the importance of a judicious dis- tribution of food among the three classes of food- stuffs; having pointed out the importance of min- eral salts, of water, of oxygen, and, to a lesser extent, of condiments, flavors and stimulants, it now becomes important to investigate some of these factors a little more carefully. During the last twenty, and largely during the last ten years, research work in nutrition has revo- lutionized that science no less than the study t)f radioactivity has revolutionized our conceptions of matter. This and subsequent chapters will deal with these revolutionary changes — changes made possible very largely by the labors of American men of science. How the dawn of the moderii era arose is an interesting bit of history. It centers itself a,round a study of the protein food. Gelatin. Early in the last century, long before a science of nutrition had been founded, the im- 52 AMINO-ACIDS 53 portance of protein in the diet was recognized. But so also was the recognition that protein is the most expensive part of the dietary. Meat, which is largely protein, became a luxury beyond the reach of the poor during the stirring days of the French Revolution and the years that followed. What was to be done? The people had to have meat because it contained protein, but perchance there were substances other than meat that con- tained this precious nutrient? Others were known, such as the casein in mUk and the albumen in egg, but eggs and milk were, if anything, even more ex- pensive than meat. Then a happy idea struck the scientists of the French Academy. Were there not enormous quan- tities of bones discarded yearly out of which gelatin could be extracted, and was not this gelatin a pro- tein? Behold the panacea! D'Arcet invented an economical method for extracting the/gelatin, and a committee of the Academy of Medicj:ne, in solemn session assembled, declared the process and the food aU that could be desired. The learned Academy's report was published in 1814. On the strength of this report the French Government began their experiments at the hos- piteds. Why sick people rather than criminals were selected is not clear. To-day when the United States Department of Public Health desires to ex- periment with people, it usually turns to Sing Sing and places of that kind ; and then the experiment is conducted with volunteers only. The sick people in some of the French hospitals 54 VITAMINES were given gelatin, in place of other proteins. They digested it easily enough ; gelatin jellies in fact are easily digestible. But after a time the sick people fell sicker, — ^in such numbers and under such con- ditions that only the change of diet could account for it. Like the politician who is the hero to-day and becomes the traitor to-morrow, poor gelatin was thrust from its lofty pedestal back into the refuse from which it had been rescued. But what was the matter with gelatin? Why could not this protein substitute the proteins in meat, egg and milk? Years elapsed before a satis- factory answer was found. At any rate, the world in the meantime learnt the lesson that merely giv- ing a man 100 grams of protein without specifying the kind of protein meant no more than giving a man food yielding a sufficient number of calories, without, however, specifying how the food was to be distributed among the classes of foodstuffs. But life on this earth continued, and many died and many more were born, because instinct and experi- ence led us to do the things we did do. To find an answer to the question why one protein is less nutritive than another requires an examination of the fate of the protein after it has entered the system. But here the earlier investigators suffered from the drawback that they were ignorant of the chemical constitution of proteins, and were there- fore ill-equipped to study the changes of the pro- tein in the system. Amino-Adds. It was subsequently discovered — AMINO-ACIDS 55 by Emil Fischer * and others— that the proteins are made up of chemical units in much the same way that words are made up of letters ; and just as the twenty odd letters are sufficient to form the many different words in our language, so the eighteen or more chemical units, obtained by analyzing pro- teins, are sufficient to form the different proteins with which we are familiar. These chemical units are known as amino-acids. When a protein such as is found in meat is eaten, the several juices act upon it and break it up into its amino-acids. We have learnt that this breaking up of a protein in the digestive tract is a necessary prerequisite to absorption and assimilation. The system cannot absorb protein as such.** Introduce protein directly into the blood and it acts like a poison ; but introduce the amino-acids out of which the proteins are buUt, and all goes well. The factories in which the protein is prepared for absorption are the stomach and the small intestine. Here the proteins are changed to amino-acids, which then find their way into the blood stream, and thence to the cells. In the cells occurs the reverse process of what takes place in the digestive tract; instead of break- ing up proteins into amino-acids, the latter are * Professor McCollum suggests that "Kossel's name be substi- tuted for Fischer's, since Sossel did so much more pioneer work in showing the nature of the protein molecule and in the discovery of four amino-acids, whereas Fischer only discovered one. I have felt that more credit is due to Kossel than is usually given him. ' ' ** A little may be absorbed unchanged, but the amount is negli- gible. 56 VITAMINES joined together to form proteins. Analysis gives place to synthesis. But why this breaking down of proteins into their units if these act merely as nuclei for rebuild- ing protein? A perfectly fair question. But re- member that we are not rebuilding the same pro- tein. The same letters will give you different words, depending upon the arrangement of the letters. The same bricks wUl give you different houses, de- pending upon the arrangement of the bricks. The same amino-acids will give you different proteins, depending upon the arrangement of these amino- acids. That is why the Germans call the amino- acids the Bausteine or building-stones. Not all proteins contain the same amino-acids. Some proteins contain more of one amino-acid than another ; others are deficient in one or more of the acids. In order to build up that peculiar protein which we find in the tissues, the tissue protein, the cell selects those amino-acids it needs and discards the rest. You may ask, why if what the cell needs is not the protein but the amino-acid, the diet should not rather consist of amino-acids, fats and carbohy- drates, rather than proteins, fats and carbohy- drates? Unfortunately, nature insists upon sup- plying us with the more complicated proteins; just why we do not know.* But nature has consider- * This is not quite true. The physical chemist will tell you that proteins are colloids, whereas amino-acids are crystalloids, and there are reasons why plant and animal material should be in the colloidal state. AMINO-ACIDS 57 ately supplied us with a factory, known as the di- gestive tract, where the proteins can be changed into amino-acids. But before we dismiss the general metabolism of proteins — the changes that substances undergo in the system — we must refer to another topic, be- cause of its relationship to the subject of just how much protein the body needs. We have already seen in earlier chapters how the subject of protein needs has given rise to much discussion. Most of the experiments conducted in this direction have tended to point to an amount of protein consider- ably less than that ordinarily used by man. But the more recent studies have shown us that not all of the protein ingested is utilized by the cells. As we have just seen, only a select number of the amino-acids formed from the protein are taken up by the cells to form tissue protein ; the rest are dis- carded. Is it not therefore necessary to eat more protein than would at first hand appear, if only to insure an adequate supply of those amino-acids needed for tissue building? Arguments such as these have led to the revision of the diets of our soldiers in favor of a relatively high protein con- tent. Why Gelatin Is a Poor Type of Protein. But now it is time to turn back to our gelatin. A care- ful analysis of this protein has shown that two of the commonest amino-acids — so common that they are found in most of the other proteins — are miss- ing in gelatin. These amino-acids are known by the high sounding names of tyrosine and tryptophane. 58 VITAMINES Might not these two amino-acids be essential to tissue up-building? Might not the absence of these two amino-acids explain the inferiority of gelatin to other proteins? If such a view is sound it should be capable of being put to the test of experiment. And surelj enough, where gelatin (plus fat plus carbohydrate plus mineral salts, etc. ) alone was found to be in- adequate to sustain animals, the same diet to which the two amino-acids tyrosine and tryptophane were added, met all requirements. In this experiment, based on the laborious work of many scientists stretching over a decade, is to be found the key to much present-day activity in the science of nutrition. It has led to an entire revision in the feeding of armies and nations. This will be made clearer as we go on. Though there are some eighteen amino-acids known which, in varying proportions, make up the composition of the different proteins, only the in- fluence of three or four of these acids on the diet has so far been at all extensively studied. But a study of the influence of these three or four has already afforded us some amazing results. The Amino-Acid Gmitent of Proteins. Let us present the reader with some quantitative studies. Turn to page 189 and examine the percentage of amino-acids isolated from various proteins. What does such a list show? Some of the pro- teins do not contain the amino-acid glycocoll; others do not contain tryptophane ; stUl others are deficient in lysine and cystine. (Strictly speaking^ AMINO-ACIDS 59 it is incorrect to speak of a protein as "containing" such and such amino-acids. These amino-acids be- come evident only after the protein has been decom- posed.) To what extent are these amino-acids needed by the organism, and what happens if the only source of protein in the diet is deficient in one or more of these amino-acids? The answer has already been supplied for gela- tin. Unless the missing amino-acid tryptophane (and tyrosine) is added, death occurs. Now suppose we arrange a diet in such a way as to vary from time to time the protein it may con- tain. Let us assume that we have fixed upon the type and amount each of fat, carbohydrate, mineral salts; and that we allow plenty of water and plenty of air; and that we adhere to such a diet throughout the series of trials. From time to time, however, we shall replace one protein, say casein, with another, say zein. If the substitution of zein for casein causes ill-effects, we may reasonably assume that this is due to the absence of one or more amino- acids from the diet. Suppose we d*dd one or more of such amino-acids to this otherwise deficient diet and the animals that we experiment with begin to thrive again; are we not justified in concluding that our assumption was correct? This, in fact, is the procedure that Professor Hopkins of Cambridge, Dr. Osborne of the Connec- ticut Experimental Station and Professor Mendel of Yale have adopted. The last two investigators in particular, who have done all their work jointly, have enriched this phase of the science VTith much 60 VITAMINES of value. Let us follow Osborne and Mendel in their path. Drs. Osborne and MendeVs Experiments. They selected white rats for their experiments, for a num- ber of reasons. Eats are small, easy to handle and multiply rapidly. They usually live not more than three years and "280 days suffices to complete the entire period from growth to maturity"; which means that several life cycles can be watched. Not only does the rat come under observation during a period which would correspond to about 60 years in the life of man, but the effects of the diet on the offspring may also be noted. In fact, several gen- erations are included in such a survey. Now what was to constitute health and what ill- health? In the infant a steady increase in weight is taken as the best criterion of normal development. Of course we cannot always be sure that an increase in weight means just this, but in a large percentage of cases it does; and it becomes a simple way we have of measuring progress. A certain sign of the sick man returning to a state of normality is when he gains weight. We say he "puts on flesh." Under normal conditions the adult neither gains nor loses. How to "Plot" Curves. Drs. Osborne and Men- del adopted this standard of measuring progress by noting the. increase in weight of their rats. To present their results graphically in a way that a mass of figures never could, they plotted curves in much the way that nurses in hospitals and the "modem" mother do when they wish to keep an easily presentable record of their infants' gain in AMINO-ACIDS 61 weight from week to week. Such a nurse or mother first records in her notebook the various dates and corresponding weights of the child. Thus, to take an example, we may find some such record as this : Week Weight At birth 6 pounds 1- ounce At the end of the first week 6 " 4 ounces At the end of two weeks 6 " 10 " At the end of three weeks 6 " 15 " At the end of four weeks 7 « 4 " At the end of five weeks 7 " 13 " and so on. Now she takes her square-lined paper and marks off suitable horizontal spaces to indicate time and vertical spaces to indicate weight. A con- venient way she finds is to call every seven squares in a horizontal direction one week (7 days), the number "1" at the end of the first seven squares in- dicating one week, "2" at the end of the first four- teen squares indicating two weeks, and so on. Simi- larly along the vertical line, since she deals with pounds and ounces, she selects sixteen squares to represent one pound; so that at the end of the first sixteen squares she puts the figure "1," represent- ing one pound ; at the end of thirty-two squares she puts "2," representing two pounds; and so on. At birth (zero week) the child weighed 6 pounds 1 ounce. You travel vertically until you reach the figure 6 and then you go one square more. You make a cross at that point. At the end of the first week the child weighs 6 pounds 4 ounces. You 62 yiTAMINES FiGTJEE 1. — Growth op an Infant For an explanation of this chart, see page 60 of text. 0»' "i" Pvunds ^ *> V \ Jt :::::E., :::: _ I -- --5 _ — - ^ ..:...3l.:::: «- k : : :::fk:::: (> y^ j>.-»-.....k..„ •^ - - _ 'J! -|»- --^ S^ _5^ __. ^_ _ — ^. - V V ep " -~-4j4--- ..„_._i^" _._._.. 1 ■^■ "• ^ j_ ^ ^._ »»', ^ I Z- '^ = c tt 5 -* Si '*to -:---e^B:-Jl..--_ ^ ..... ..... q__ ■■ ■= " " " ■"* ■ ■» ; jr •fc 2 « ^ ^ * ! :: Si J 5 — e £ '-• 5 r 5 ! -f^^ 5 3^ 5 «. ' ^£^5 t „»_g___^ jJlg„ ^ %^< ^ 5 ^L ■* i' , ^ «.. "• r ^^ L % k ^ . »>» ........ .. •» H c \ V 1 \ 64 VITAMINES travel horizontally until you reach "1" (one week) and vertically until you reach "6," and then go four squares above that (to represent 4 ounces). You make another cross here. And you continue that from week to week. Then you draw your line through the intersection of your crosses and you get a curve such as is shown in figure 1. What do you gather from such a chart? So long as the curve is up an incline, so long as you are traveling up-hill, the child shows a constant in- crease in weight, and therefore represents a prob- able normal development. The steeper the incline the more rapid the increase in weight. But where the slope reverses and goes down, instead of up- hill, the curve represents «, loss in weight and the child is therefore not developing as well as it should be. From the curve under discussion (figure 1) you will notice that aside from a loss in weight during the first few days (a regular occurrence) , the curve slopes steadily in an up direction until the tenth week is reached. Then there is a decline with the eleventh week. The doctor diagnosed the child's loss of weight as probably being due to insufficient nourishment, or perhaps to unwholesome nourish- ment, — ^because the mother was nervous. He sug- gested a supplementary milk diet. Notice how from the thirteenth week the curve starts up-hUl again. If I have dwelt for some time on this simple example, it is because once the reader understands the significance of such a curve as is represented in AMINO-ACIDS 6* figure 1, he will have no difficidty whatsoever in understanding the subsequent charts. And as has already been stated, this graphical method of repre- sentation has the advantage over mere figures in that you can take in an entire experiment at a glance. Afdmal and Yegetable Proteins Compared. Now turn your attention to chart 2. A diet consisting of the protein casein* (found in milk) which, as you may gather from the table in the Appendix, does not contain the amino-acid glycocoU, caused rats to grow and gain in weight; for notice the in- cline of the curve marked "casein." Evidently gly- cocoll is not indispensable. When the protein glia- din (derived from wheat or rye) is substituted for casein, the incline of the curve is nowhere near as sharp. -The increase in weight is very, very gradual. Gliadin, as the table shows, is deficient in the amino-acid lysine, and the failure to gain so rapidly may be due to this deficiency. The foods other than protein that Drs. Osborne and Mendel used were starch, sugar, lard, agar and inorganic salts. The agar was added "to form an indigestible intestinal 'roughage,' " and the in- organic salts were given either as a mixture of the pure inorganic salts, or in the form of "protein- free milk" — a product representing the milk from which fat and protein have been removed. In their * And, of course, fat, carbohydrate, etc. Please remember that in all the examples here given, the one constituent of the diet that varies is the protein; the other constituents are not changed dur- ing such experiments, though they are always added in proportiona that experience has taught to be beneficial. 66 VITAMINES Figure 2. — ^Amino-Acids and Growth Showing typical curves of growth of rats main- tained on diets containing a single protein. On the casein food (devoid of glycocoll) satisfactory growth is obtained; on the gliadin food (deficient in lysine) little more than maintenance of body weight is possible; on the zein food (devoid of glycocoll, lysine and tryptophane) even mainte- nance of body weight is impossible. Osborne and Mendel: J. A. M. A., 1915. 0,0) -J o z i s i S 5 o s n 1 1^+1 1 1 1 1 1 r» J \ 1 1 TtsLi III 11 i^k. I'M ^iwj 111 ! "». 1. ' ' 1 ';j_ 4_ ::::::"""! : 5s _^,::±_:_. .:;::: :;::... .i'».'i, J . _ . « ""'!" xit ji — "^ "<;>tx ::::: iSLpw, < [I'll ":: :":: :::xS; -.:":: ::":"::..:: J J ! u 1 i_- -_^__^__L_u_-_| — ^^___L^.±..J:_.- Eg I i J [-|r;-J ' *-- _L_L^_M |__L L._.y T — i^~.7jZIZ71:~'~~ + _±___x^+ ±-&- i- :w:±:::^::^ ::±"Ttt:::::xr:::±:::::::±::?y:: 1 „ : k. - -1^ — 1 -f — Lj — 1 — t _ 'T il u U L i"^ — i' "3 ""::-::.::: jj" IT" ,. -! - J . Lj^ L J — L — \11 |:::ffi:i^::g:::: ::Si;::i:S:Ml;:::;:;:::l -1- J j-L J- jX _lj e -i±^ + -|--± ■^"i'" "^"H=+=^f "^'''^""T^ — ^" 1 ._X-X ^ — ixi — I "i. — X ^ — ^ — (-5 ±i J ==== = = !::: ilirrlE!:::::::: i---T : 68 VITAMINES subsequent Titamine studies these investigators made frequent use of this "protein-free milk." In answer to the criticism that "protein-free milk" is not free from nitrogen compounds, and ^'therefore makes a comparison of the biological yalue of different proteins" difficult, Prof. Mendel writes: ". . . It is true that protein-free mUk which we used in our earlier experiments contained a certain modicum of nitrogenous matter — a fact which we ourselves pointed out. It is not unlikely that this may have altered the numerical values in the comparisons which we made earlier between the different proteins. In recent years we have no longer used this product. In fact at the present time whenever it is desired to compare protein values we employ a yeast concentrate which gives no biuret reaction [the 'biuret' test is one used to de- tect proteins] . I believe that the fundamental con- ceptions regarding the importance of cei-tain amino- acids is unaltered by any of the comments which have been made." Now notice the interesting situation that arises when zein (derived from maize) becomes the sole source of protein. At first the rats under examina- tion were given a mixed food containing several dif- ferent proteins, and the animals thrived splendidly. Then after about two weeks the diet was so changed as to replace the mixed proteins with the single protein zein. See how the curve suddenly swerves. It actually goes down-hill. This down-hill slope of course indicates that the animals are losing weight and are on the decline; for remember that we are AMINO-ACIDS 69 not dealing with rats that have reached maturity and that are merely too fat, but young rats in the growing stage. If rats in the growing stage lose weight, particularly if the loss continues over many weeks, then something is surely the matter — ^just as under similar conditions all would not be well with an infant. Zein is devoid of the amino-acids glycocoU, lysine and tryptophane. The experiments with the milk protein, casein, have proved that glycocoU is not essential; for though casein contains no glycocoll, the animals thrived. Where lysine alone is defi- cient in the protein molecule there is more or less maintenance; that is, neither a decided increase nor decrease in weight (see the curve marked glia- din) ; hence the decided downward slope of the curve in the case of zein would lead to the belief that the indications of rapid decline are probably due to the absence of the amino-acid tryptophane (and perhaps also cystin. See later experiments). Th« three experiments just described are ex- tremely suggestive, for they point to the indispensa- bility of the amino-acids lysine and tryptophane. The indications are that no matter how many calo- ries a diet yields, no matter how well the diet is dis- tributed among the foodstuffs, no matter how much protein is given, */ the protein part of the diet is defideni in the amino-aeids lysine and tryptophane, life is impossihle. To prove this still further, Drs. Osborne and Mendel fed rats with a diet in which the protein consisted of zein only. Note the loss in weight 70 VITAMINES Figure 3. — ^Amino-Acids and Growth Showing the effect of the amino-acids trypto- phane and lysine to zein which fails to yield them. With zein alone there is nutritive decline. The addition of tryptophane permits maintenance but not growth. The addition of tryptophane and lysine enables the animals to make considerable growth. Osborne and Mendel: J. A. M. A., 1915. 72 VITAMINES Figure 4. — ^Amino-Acids and Growth Showing the favorable effect on growth by sup- plementing a protein (zein) incapable of maintain- ing animals when it is the sole protein furnished in the diet with a more "perfect" protein (lactalbu- min). The proportion of the lactalbumin used — 4.5 per cent — was of itself insufflcient to promote growth well. It evidently furnished the amino-acid groups lacking in the zein. Osborne and Mendel: J. A. M. A., 1915. 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Aspartic acid... Glutamic acid. . SerinA ■I 6 '5 '1 a B s ■E j'S'! (3^ • '1^ I 190 VITAMINES o Ph CQ i= O S i O iJ U o ^ m . M •^ a ii snniXqx ntjsEia iiOQ — ^niasBO mtj'BpQ mqoiSoraaaq esiOH — niqoi£) Enooaoa 3{XTS esanBdep to -otoo iq ■* ■ 00 Tt; oj O 03 ■ iH tH* Cci eq in la IS in lo i-i «d W CO 00 •* Oi b-; in -^ CO t> oq »0 CD t-i i-H iH CO oq cq O W t^- •«* C5 lO IH o w oci -t^ i>- oq -^ »n m o in 00 w Oi «D in OlHt^OJCOCQrH lrioO'«^'<*icql£niHiH in 00 o iH oq -^ o !0 o iH oq" in o o tH o o o t^ o oq 0; ;cq oq (M OCO r-i O • in oooq t-00 •« ;Os coo t-o S • rH t^ 04 in rH >■ Ph ooiH^-^'oqcd oq " t-^ t-H ■*■ rH o CQ oq o CO in oq rH ** i-H CO iH "So 2 o^tS g rt a> si fl^U a a> m 2 Cb CD O Eh << W h1 100, 101, 128, 131, 146, 158, 160, 172, 188, 205, 207, 209 Mental work, effect of on energy requirements, 14, 15 Milk, 19, 91, 210 poor in water-soluble C vita- mine, 145, 210 importance of, 169, 170 breast, 174 modified, dried and con- densed, 175 value of, for child, 176 composition, 187 vitamine content, 192 Milk sugar (lactose), in infant feeding:, 86 vitamine in impure, 103 MiMikan, 204 Mineral matter, 36-45, 164, 205 elements iny 37 function of, 38 compared with organic food- stuffs, 45 MocTceridge, 114 More, 210 Mother, the nursing, 173, 201, 203, 210 Muir, 204 Mwrlm, 212, 213 Nansen, 150 Neutrality, body, 40 Nitrogen equilibrium, 27, 28 Organic chemistry, 110 Osborne, 59, 60, 65, 69, 80, 99, 100, 101, 128, 131, 158, 205, 207, 209 Osier, 120, 211 Oxidation in the body, 10 Oxygen, 2, 164 function of, 47-48 218 INDEX Palmer, 207 PeDagra, 153, 209 in the South, 153 symptoms, 154 not an infection, 155 type of diet a factor, 156, 158-9 outbreak in Egypt in 1918, 156 Phosphatids, 43 Phosphorus, 42 for the brain, 43 Pitz, 143 Plants, influence of vitamines on growth of, 113 see auximones Polyneuritis, in fowls, 118 identical with beriberi, 119 see water-soluble B vitamine Priestley, 2 Protein, 17, 18, 19, 20, 21 function of, 21, 23 requirement of, 25, 26, 29, 57 objections to a low diet of, 30, 31, 32 amino-aeid content of, 58 animal and vegetable, com- pared, 65 importance of certain amino- acids in, 69 see proteins "Protein-free milk," 65 Proteins, biological value of different, 80 of animal origin, 80 of vegetable origin, 80 see protein Eats, use of, in experiments, 60 Eice, polished, 119 cured, 119, 122 Sichardson, 115 Eiekets, 128, 209 due to absence of fat-soluble A, 129, 131, 133 anatomical features, 130 Eiekets, diminished calcium content, 130 symptoms, 130 prevention of, 199 Soffers, 184 Soth, 212 Salt, 40 SooU, 150 Scurvy, 137, 208 symptoms, 137 due to vitamine deficiency (water-soluble C), 138, 144, 146 animals used in experiments, 139 history of, 139 infantile, 140, 202 not bacteriological in origin, 141, 142 McCoUum's view, 143 at the siege of Kut, 148 in northern Russia, 148 value of fruit and vegetables, 151 prevention of, 201 Seidell, 148 Sherman, 10, 178, 204, 205, 206, 212 Simmonds, 211 STcelton, 209 Smith, 212 Soap, 88 Stanton, 122 Starling, 149, 212 SteenbocTc, 207 Stefanson, 137, 149, 150 Stepp, 97, 98, 100 Stevenson, 211 Stewart, 205 Stimulants, see condiments Stomach, acid in the, 41 Stunting, 80 Sugar, 181, 187 see carbohydrates SydenstricTcer, 157 INDEX 219 TakaU, 117, 118, 120, 121 Talbot, 210 Tashvro, 14 Taylor, 179, 211 TrTptophane, significance of, 59, 69, 74 Tyrosine, signifleauce of, 59 Underhill, 160, 205 redder, 208 Vegetables, importance of, 170, 179, 180 vitamine content of, 193 Vegetarianism, 177 Vitamine, objections to the use of the word, 109 see vitamines Vitamine A. See fat-soluble A vitamine Vitamine B, see water-soluble B vitamine Vitamine C, see water-soluble C vitamine Vitamines, 91-111, 166, 194, 206 definition of, 95, 126 function of, 96, 167 two distinct, 104, 208 not yet isolated, 108, 123 and plant growth, 112-115 three types of, 138 elect of heat, 167, 208, 209; see canning and desiccation classification of, 188, 195 Vitamines, distribution of, in the commoner foodstuffs, 191-193, 196-199, 211 nomenclature, 211 see fat-soluble A; water- soluble B; water-soluble C; beriberi; rickets; scurvy; pellagra; auxi- mones; antiscorbutic; an- tirachitic; antineuritie Wanff, 206, 212 Water, 46-47, 164, 205 Water-soluble B vitamine, 104, 105, 106, 109, 166 test for, 126 see beriberi ; antineuritie vita- mine; vitamines Water-soluble C vitamine, 138, 167 see scurvy ; antiscorbutic vitamine:. vitamines WellmoM, 212 , Wells, 120 Wheeler, 157 WilUcms, 125, 167 Xerophthalmia, 128, 207, 208, 209 Yeast, a cure for beriberi, 122 vitamine content of, 193 Zein (in maize), as a source of protein, 68, 69 ZUva, 208