COLUMBIA LIBRARIES OFFSITE HLAl 1M SC:il NCI S SIANDARD HX64101037 QP141 .L972 The fundamental basi 7^ }t Columbia ®ntoergit|> m tfje Cttp of Jleto gorfe g>d)ool of Bental anb <0ral burger? Reference Htfcrarp 9 COLUMBIA UNIVERSITY THE LIBRARIES HEALTH SCIENCES LIBRARY The Fundamental Basis of Nutrition By GRAHAM LUSK Professor of Physiology, Cornell University Medical College, and Scientific Director of the Russell Sage Institute of Pathology New Haven : Yale University Press London: Humphrey Milford Oxford University Press mdccccxiv •236' Copyright, 1914, by Yale University Press First printed March, 1914 One thousand five hundred copies Reprinted June, 1914 One thousand copies QP 141 PREFACE This lecture is published in its present form that educated people may be able to obtain a better under- standing of the principles of nutrition than is to be derived from current popular writings. The lecture was delivered in November, 1913, as the Anniver- sary Address of the New York Academy of Medicine. Graham Lusk. Cornell University Medical College, New York City. CONTENTS I. Historical .... II. The Constant Need of Fuel III. The Constant Need of Protein . IV. Habits of Diet V. The Curious Disease of Beri-beri VI. Criteria of the Monetary Value of Foods .... 1 6 16 27 36 41 Digitized by the Internet Archive in 2010 with funding from Columbia University Libraries http://www.archive.org/details/fundamentalbasisOOIusk I HISTORICAL The object of this paper is to present the subject of nutrition in its broad general aspects and to suggest the possibility of the practical application of some of the facts which years of labor through many generations of workers have brought to light. It seems as though mankind had a right to a knowledge of the value of the foods which a boun- tiful Nature has provided for his use. Even among educated persons one may hear the grossest errors of judgment regarding the nutritive value of a hen's egg and few of those who eat in restaurants realize that the greater quota of nourishment which is brought to them lies not in the specific dish served but in the bread and butter which ostensibly is presented as a gift. From the earliest times it was evident that al- though an adult partook of a great deal of food, he did not gain in weight. Hippocrates believed this to be due to a constant loss of insensible perspiration and to the elimination of heat, which he conceived to be a fine form of matter. Galen, six hundred years later than Hippocrates, was no further advanced in his conception of nutrition. For thirteen hundred years after Galen intellectual progress lay dormant under the spell of the Dark Ages. 2 BASIS OF NUTRITION One of the first inquirers of the Renaissance, the brilliant Paracelsus, explained the phenomenon of nutrition as being under the supervision of an archeus, a spirit which dwelt in the stomach and separated the food into the good and the bad, the good being used by the organs of the body, and the bad eliminated. A true conception of the nutritive process could only be formulated when a knowledge of the exist- ence of the various gases was revealed. It was Lavoisier who first showed that when an organic substance burned, the products of combustion were equal to the sum of the original substance and oxygen. Oxygen had but recently been discovered by Priestley. Lavoisier burned plants and found that carbon dioxide and water resulted. He, there- fore, concluded that they contained carbon and hydrogen. Animals contained nitrogen in addition. This was the first analysis of organic material. Lavoisier went further and found that an animal or a man, like a burning piece of wood, absorbed oxygen and eliminated carbon dioxide. He dis- covered that the process of heat production in man was one due to oxidation, that the prevailing idea that particles of air entered the salt and sulphur con- taining blood and there caused fermentation was untrue. Lavoisier measured the heat given off by a guinea pig by noting the quantity of ice melted by the animal when placed in a hollow block of ice, and HISTORICAL 3 he measured the gases given off by the animal in order to determine whether the heat produced could be accounted for by the oxidation going on. He, furthermore, determined that oxidation in man was increased by giving him food, by causing him to do mechanical work or by subjecting him to the influence of cold. Reflecting upon these facts during the troublous times of the French Revolu- tion, Lavoisier wrote, "Does it not seem a great injustice of Nature that the poor laborer uses more of his body substance, while superfluity, which is unnecessary for the rich, should be his portion ?" To the darkness of the history of the time belongs the fact that Lavoisier, begging, according to Carlyle, for two weeks more of life in order to com- plete his experiments, was guillotined, thereby be- coming the greatest sacrifice of the insensate fury of his age. (For this earlier literature see Carl Voit: L'eber die Theorien der Ernahrung der tierischen Organismus, Miinchen, 1868.) The progress of science is a history of great dis- coveries of fact which become established, and of destruction of theories which are temporary mental conclusions shown later to be untenable. Nor can a master mind like that of Lavoisier escape the appli- cation of this universal law. He showed that animal heat was due to a process of oxidation but he believed that the heat produced was caused by the union of oxygen with carbon and with hydro- 4 BASIS OF NUTRITION gen in the lungs. It was not till sixty years after his death that it was fully realized that the heat pro- duction was due to the oxidation of protein, fat and carbohydrate within the different organs of the body. Carl Voit, to whom more than anyone else the world owes its fundamental knowledge of nutrition, was accustomed to say in his lectures, "Continual decompositions of matter are always going on in the living cells, and the energy liberated in these decom- positions is the power upon which the motions of life depend. Phenomena of life are phenomena of motion." In truly poetical language Rubner, the most eminent of Voit's pupils, has written, "Mute and still, by night and by day, labor goes on in the workshops of life. Here an animal grows, there a plant, and the wonder of it all is not the less in the smallest being than in the largest." The workshops of life require fuel to maintain them, and a necessary function of nutrition is to furnish fuel to the organism that the motions of life continue. Furthermore, the workshops of life are in a constant state of partial breaking down and materials must be furnished to repair the worn-out parts. In the fuel factor and the repair factor lie the essence of the science of nutrition. These two factors operate to bring about death from starvation, either the body's own store of fuel becomes exhausted or a part of the machinery HISTORICAL 5 necessary for life wears out. As regards the course of death from starvation, there exists the written record of the explorer Hubbard. The following words are believed to have been penned a few hours before his death in Labrador. "I am not suffering. The acute pangs of hunger have given way to indif- ference. I'm sleepy. I think death from starvation not so bad. But let no one suppose I expect it. I am prepared — that is all." Hubbard's biographer quotes the following as showing the spirit of the lost explorer, as it indeed represents the spirit of all investigators : " Something hidden. Go and find it. Go and look behind the Ranges. Something lost behind the Ranges. Lost and waiting for you. Go." II THE CONSTANT NEED OF FUEL The light and heat of the sun playing on the green leaf of the plant cause carbon dioxide and water to unite to form sugar. Heat is absorbed in the process and oxygen is given off to the atmos- phere. If one gram of sugar be placed in a very strong, closed steel receptacle into which oxygen, under a pressure of 450 pounds to the square inch, is conducted, and then if the sugar be kindled by an electric spark it will be completely burned to carbon dioxide and water and exactly the same quantity of heat will be liberated as was obtained from the sun in the original manufacture of the substance. If the steel receptacle be placed in a liter of water in which a thermometer has been put it may be noticed that the temperature of the water rises nearly 3.75°. After making certain corrections, it may be proved that 1 gram of glucose, when oxidized, yields heat sufficient to raise one liter of water 3.755° C. Since the measure for heat is a calorie or that quantity of heat required to raise 1 liter of water 1° C, it fol- lows that 1 gram of glucose yields 3.755 calories of heat. This apparatus measures the heat of combus- tion of organic substances like sugar, starch, meat, fat, etc., and is called a bomb calorimeter (a measurer of calories). The calorie or heat unit is as much an exact value for measurements of heat THE CONSTANT NEED OF FUEL 7 as are a quart or a pound for measurements of volume or weight. When protein is burned in the bomb, the nitrogen of it is converted into nitric acid, but when protein is burned in the body, its nitrogen is not oxidized but is eliminated in the form of urea, so the heat produced from protein in the body is always less than that measured by the bomb. Sugar, however, yields the same products in the bomb and in the body and, therefore, the amount of heat produced is identically the same, no matter where the oxidation takes place. The same is true of fat. One gram of the ordinary food stuffs when oxidized in the body yields the following number of calories : Calories Glucose 3.755 Cane sugar 4.0 Starch 4.1 Fat 9.3 Protein 4.1 It has been said by some that they never will be converted to the belief that a knowledge of calories in nutrition is valuable. These persons must be reasoned with and persuaded to listen and they cannot then but be convinced. The law of the conservation of energy holds that power cannot arise from nothing. Power must be derived from some store of energy, from energy 8 BASIS OF NUTRITION which is potential. The store of power in the food stuffs is liberated when they are oxidized in the body. This power becomes the source of the mo- tions of life, and in the resting organism is finally liberated as heat. If this be true, then if one can measure the quantity of protein, fat and carbo- hydrate (sugar) oxidized in an animal in twenty- four hours one can calculate the quantity of heat which will arise from this process. If, at the same time, the animal can be placed in a calorimeter, which measures the heat actually given off during the period, the two computations should exactly agree. To Rubner belongs the glory of being the first to have demonstrated this truth. Calorimeters have since been constructed to measure the heat production in man. The labors of Atwater, Rosa and Benedict have confirmed the application of the law of the conservation of energy to man. The oxygen intake and carbonic acid outgo give a measure of the oxidation of the food stuffs, and the heat given off by the body is found to be equal to the quantity of heat which would have arisen from the oxidation of just that quantity of protein, fat and carbohydrate estimated to have been destroyed. In a calorimeter built for the Russell Sage Insti- tute of Pathology in Bellevue Hospital, it has been found that if a definite amount of alcohol be burned THE CONSTANT NEED OF FUEL 9 in a lamp within the apparatus, the heat measured during a four-hour period is exactly that amount which the theory would call for. Theory Found 212.57 211.88 Doctors Du Bois and Warren Coleman have dis- covered that a typhoid patient, during a period of five hours of rest in this calorimeter, produced the same number of calories as were calculated he should produce from the materials which were oxidized in his body. Theory Found 422.59 419.78 Contemplation of such a result as this drives home the fact that if this typhoid patient is to be kept from losing his own body muscle and fat, he must be given the equivalent of 422 calories in food substances during a five-hour period. If one measures the hourly heat production of a normal resting man, one must be convinced of its constancy. The human furnace requires a certain quantity of fuel to support the activities of life. Measurement of the total heat production, there- fore, becomes a measurement of the intensity of the life processes. The quantity of heat produced by mammalia of the same size is fixed and definite and can be closely predicted in advance. It is not dependent on the 10 BASIS OF NUTRITION weight of the animal nor upon the relative size of the individual cells. Thus, the size of the cells which make up the substance matter of a mouse is not very different from the size of the cells of the horse, yet a mouse produces 452 calories per kilo- gram of body weight in 24 hours and the horse 14.5 calories. The mouse requires thirty times more food per unit of body weight than the horse. How- ever, Rubner has shown that all well-nourished mammals produce the same number of calories per square meter of surface. A normal man, well nourished, who is resting quietly in his bed in the morning, having been with- out food for fifteen hours, will manifest a minimum level of heat production. This level may be called the basal heat production. The following table has been prepared to show the constancy of energy pro- duction under these circumstances : [dividual B Weight in kilos 83 Calorii per kilo 1.01 1.03 1.01 0.9S 0.96 1.00 1.15 1.07 1.13 ;s per hour per square meter surface 35,7 G. L 78 36.5 D. B 74 35.3 R c 74 68 32.5 31.7 J. R H 66 62 32.7 37.0 G 56 34.0 T. C 49 37.7 THE CONSTANT NEED OF FUEL 11 In the light of this exposition no educated man can say that he "does not believe in calories," when the energy in the food stuffs constitutes the basis of his being, and calories eliminated from his body are a measure of the sum total of his physical activities. Food is the fuel of the human furnace, and must be furnished to that furnace in accordance with its needs. The basal heat production of an average man weighing 156 pounds (70 kg.) will be 70 calories per hour or 1,680 calories in twenty-four hours. If food be taken extra heat is produced in the body. This extra amount does not exceed 10 per cent of the basal heat production or 7 calories per hour and 168 per day, so that the maintenance requirement of this man, resting quietly in bed, would be 1,848 calories in the daily diet. Beyond this, the amount of fuel needed depends upon the quantity of mechanical work done. It becomes purely a matter of supplying fuel for the machinery. It has been shown by Atwater and by Benedict that if a person sits in absolute quiet in a chair the heat production is 8 per cent greater than when he is lying on a bed. If, however, those ordinary move- ments are made which are associated with daily life when sitting in a chair, the heat production may rise 29 per cent, or from a basal level of 70 to a level of 90 calories per hour, an increase of 20 calories. 12 BASIS OF NUTRITION Since the influence of food is to increase the metabo- lism 7 calories per hour during twenty-four hours, and the influence of a sedentary life adds 20 more calories per hour during the 16 hours when a man is up in his chair, the total energy requirement would be: Calories Night (70 + 7)X8= 616 Day (70 + 7 + 20)Xl6= 1,552 2,168 A hospital patient must be liberally fed when he receives this amount during convalescence. Addi- tional fuel in the food may be considered as a charitable contribution, a welfare fund for future use. No normal man leading a life involving sedentary occupation, should live without exercise. Only this will keep his body in proper condition. One may attempt to calculate the additional energy require- ment needed for this purpose. To walk one hour on a level road at the rate of 2.7 miles requires energy to the amount of 160 additional calories. Therefore, if the man of sedentary occupation walks two hours daily to and from his business, 320 calories must be added to the 2,168 required to sup- port him without exercise, a total of 2,488. This figure is not far from Rubner's average allowance THE CONSTANT NEED OF FUEL 13 of 2,445 calories for such men as writers, draughts- men, tailors, physicians, etc. It follows, therefore, that about 2,500 calories are required in the daily food of a man whose occupa- tion is of sedentary character. As a matter of fact, statistics show that the inhabitants of cities take this amount of fuel daily. The latest statistical proof that the food supply of a great city is regulated by the needs of its inhabitants may be found in the report of Gautier which shows that in Paris an average of 2,500 calories of energy are daily sup- plied to each inhabitant. If the exercise taken be vigorous and include hill climbing, the quantity of energy needed will be greater than when a level road is traversed. To climb on a path at the rate of 2.7 miles an hour so that the summit of a hill 1,650 feet high is attained during the hour, requires 407 extra calories. An expert bicycle rider at hard work has indi- cated an increase in oxidation corresponding to 529 calories per hour (At water and Benedict). The fuel requirement, therefore, depends upon the quantity of work accomplished. The Kaiser Wilhelm Institut has recently granted funds to Rubner in Berlin in order to establish a special laboratory in which to determine the specific fuel needs of individuals engaged in various occu- pations and trades. Computations of the diets of farmers show the 14 BASIS OF NUTRITION following interesting similarity in the fuel values of their food : Calories Farmers in Connecticut 3,410 Farmers in Vermont 3,635 Farmers in New York 3,785 Farmers in Mexico 3,435 Farmers in Italy 3,565 Farmers in Finland 3,474 Average 3,551 These figures, representing the food-fuel con- tained in the dietaries of individuals in widely dif- fering communities but engaged in the same occu- pation, show a plus or minus variation of only 6 per cent from the mean average. From the present available data one may estimate the daily fuel requirement of well-nourished adults after the following fashion: Occupation Calories In bed 24 hours 1,680 In bed 8 hours, work involving sitting in a chair 16 hours 2,170 Bed 8 hours, in a chair 14 hours, moderate exercise 2 hours 2,500 Farmers 3,500 Rider in a six-day bicycle race 10,000 It is apparent that the great numbers of men em- ployed as clerks or those employed in watching THE CONSTANT NEED OF FUEL 15 machinery require about 2,500 calories in their daily food. A boy of twelve requires about 1,500 calories daily. A baby when first born requires 100 calories per kilogram of body weight per day and later about 70. Many cases of reported chronic malnutrition of infants are in reality due to persistent undernutri- tion carried out in ignorance of the proper amount of food required by the child. In fever, the production of heat may be 50 per cent above the normal. In cases of hyperthyroidism (Graves disease) even greater increases have been observed, whereas in hypothyroidism (myxcedema) the heat production falls below the normal. It fol- lows, therefore, that increased nourishment is indi- cated in fever and in Graves disease whenever this is possible. The great practical importance of food fuel in sufficient quantity for the human machine in health and disease warrants its consideration in greater measure than has heretofore been given it. Ill THE CONSTANT NEED OF PROTEIN If a man take only fat, sugar and starch in his diet, he will be unable to maintain his life during a long period. Voit tells how an English physician nourished himself with sugar alone for a month, became extremely weak and shortly thereafter died, a victim of his scientific curiosity. A diet may be deficient in calcium salts and, therefore, the body may suffer from calcium hunger. Or a diet may be poor in iron, as a milk diet is, and the person nourished on such a diet may become anemic from want of sufficient iron to form new red blood cells. However, those who live on the usual mixed diet rarely suffer from salt hunger. Ample quantities of salts are found in milk, and iron is present in the yolk of eggs, in meat and in green vegetables, espe- cially in spinach. Salts, therefore, scarcely enter into the food as an economic question. Common table salt is purchased but its use is largely that of a flavor. When potatoes are taken common salt becomes a physiological necessity, but its ordinary use is in excess of the amount actually required. There is, however, one important material to be treasured and protected and that is body protein. There are different kinds of proteins, such as those CONSTANT NEED OF PROTEIN 17 of milk, meat, gelatin, fish, vegetables. In the pro- cess of digestion all of these different kinds of proteins are broken up into a great number of nitro- gen-containing acids. These have been compared in number to the letters of the alphabet. When they are arranged together they can make many different proteins just as there are many different words in the dictionary. Suppose the word albumin were broken up by digestion into the letters a, b, i, 1, m, n, u, then if these letters were absorbed they could be recon- structed into albumin again. Assume the same for the word globulin. Now if both albumin and globu- lin were to be formed from a common word, one would have to ingest a hypothetical substance called amglobulin, convertible into globulin if the letters a, m are abandoned to their fate or into albumin on similarly exorcising the letters 1, g. Carrying the analogy still further it is evident that if the letter b were not in the word amglobulin, neither albumin nor globulin could possibly be produced. This gives a key to the physiological value of dif- ferent proteins. Casein, the principal protein of milk, contains practically all the various elemental forms of those structural materials which enter into the different proteins used to make up the frame- work of the machinery in the living cells. The most important letters of the protein alpha- bet are the following : glycocoll, alanin, valin, leucin, 18 BASIS OF NUTRITION prolin, phenylalanin, aspartic acid, glutamic acid, serin, tyrosin, cystin, lysin, histidin, arginin, ammo- nia and tryptophan. The infant has the power of transforming 40 per cent of the protein in its food into new structural machinery, the architecture of which depends upon a regrouping of individual units formerly in the protein of milk. Thus new proteins are built whose internal arrangement is dependent upon local condi- tions in the various organs of the child. Now it is apparent that proteins are especially valuable if they contain an array of units which, when reunited, form body proteins. Such food proteins are those of milk, meat, eggs and fish. It is also apparent that proteins like gelatin and zein, in which one or more of the necessary units are lacking, can never be reconstructed into new body protein. Finally, it must be clear that when the units are in a very different ratio to one another from that in which they exist in body protein, they must be of inferior nutritive value, since large quantities must be broken up in order to yield that quantity of cer- tain units necessary for the construction of animal protein. Such inferior proteins occur among the plants. Plant proteins are eaten by the ox and are reconstructed into beef proteins, with the oxidative elimination of the excess of chemical units which are unnecessary for the structure of the animal cell. In this way beef protein attains a higher biological CONSTANT NEED OF PROTEIN 19 value for the nutrition of man than is possessed by vegetable proteins. The body of an average man weighing 156 pounds contains about 30 pounds of protein or 20 per cent of the live weight. If the man starves he will lose 5 parts per thousand of his protein store daily. If he be given fat and carbohydrate in large quantity, the daily loss of body protein may be reduced to 2.5 parts per thousand. This loss of body protein repre- sents the irreducible minimum of wear and tear on the constituent parts of the machinery of the cells. Murlin has shown that this minimal destruction cannot be prevented by giving gelatin with fat and carbohydrates. Gelatin contains many of the struc- tural units of meat protein but in very different rela- tive amounts and it contains no tyrosin, cystin or tryptophan. It, therefore, has not the chemical units necessary to repair the worn-out parts of the cell machinery. Murlin found, however, that if this quantity of protein which constitutes the irreducible minimum of wear and tear on the cells was added in the form of beef heart to the gelatin diet, the waste of body protein stopped at once. He found that the wheat proteins of cracker meal were far less efficient in protecting the body from protein loss than were the proteins contained in beef heart. Thomas, in Rubner's laboratory, took starch and sugar in large quantity in his diet and determined the minimal loss of protein under these circum- 20 BASIS OF NUTRITION stances. He then took meat equal in amount to this minimal quantity destroyed and found that if the food was divided into six portions and taken four hours apart, there was no loss of body protein. These experiments show how necessary it is that the body have a constant replenishment of its pro- tein store. The experiments of Thomas were carried still further and showed the relative bio- logical value of the proteins of different origin. The following minimal amounts were required to protect body protein from loss : Meat protein 30 grams Milk protein 31 grams Rice protein 34 grams Potato protein 38 grams Bean protein 54 grams Bread protein 76 grams Indian corn protein 102 grams There can be no doubt whatever as regards the superior value of meat, fish, egg and milk proteins over those of bread, beans and Indian corn. The proteins of rice and potato, however, hold an inter- mediate position. Such facts as these should make it possible to classify proteins into groups according to their physiological value. Milk is sold in New York as of three grades, A, B and C. In like manner the proteins of the food stuffs could be labelled A, B CONSTANT NEED OF PROTEIN 21 and C according to their physiological value, and to group D might belong gelatin and some other pro- teins which cannot replace the body protein that is continually wearing away. The question will at once be asked, Why do the vegetable proteins behave differently from meat and milk proteins? The answer is given by the work of the American investigators, Osborne and Mendel. Osborne, for years, has prepared vegetable proteins in their purest form. He has found, for instance, that the principal proteins in wheat are two in num- ber, existing in almost equal amounts, called wheat glutenin and wheat gliadin. Glutenin, on analysis, yields about the same integral chemical substances as casein. Gliadin, the alcohol-soluble wheat pro- tein, does not contain the unit known as lysin ; and it contains 37 per cent of glutamic acid, of which substance milk and muscle protein contain only about 10 per cent. Osborne argued from these facts that wheat gliadin would not be as valuable in nutri- tion as milk protein. The question was, how to com- pare the physiological value of the different proteins. The method adopted was to feed young albino rats, just weaned, with a diet containing milk sugar, fat, milk salts and the protein to be tested, and then to observe the curve of growth of the rats and see if it were normal. When casein was the protein added to the diet, the rats showed a usual rate of growth and lived a year and more without the slightest 22 BASIS OF NUTRITION abnormality. It was found that the growth took place freely when 15 per cent of the calories in the diet were in the form of protein. With white mice, on the contrary, nearly 25 per cent of the calories in the diet had to be in protein, if the normal develop- ment of these smaller and more rapidly growing organisms was to be provided for. These figures may be contrasted with 7 per cent of calories in pro- tein in human milk, which adequately provides for the growth of the infant. The diet of rats required 3 per cent of milk salts whereas mice required 6.8 per cent for proper growth. These, therefore, are factors of considerable importance. Not only casein but also lactalbumin of milk, ovalbumin of egg, edestin of the hemp seed, and glutenin of wheat, were able, each in itself, to be an all-sufficient source of protein supply when fur- nished with the diet of fat carbohydrate and milk salts above described. Wheat glutenin, therefore, is an adequate pro- tein providing for maintenance and growth. How- ever, when gliadin from wheat was the protein given to rats, growth was almost inhibited. The weight was maintained but the animals were dwarfed. The capacity for normal growth was present, for addi- tion to the diet of an adequate protein like casein caused normal growth at any time, even though the change in the diet was made after the time when full growth would have been attained under conditions CONSTANT NEED OF PROTEIN 23 of normal nutrition. Furthermore, addition of the missing protein unit lysin to the gliadin diet caused the rats to grow. This analysis shows that gliadin, which represents nearly half the protein of wheat, is of inferior food quality not only on account of its large content of glutamic acid but also because it lacks a necessary letter of the protein alphabet, lysin. It interprets the results of Thomas, which show that it requires more protein in bread to pro- tect the body from protein loss than it does when milk or meat are ingested. Other vegetable proteins such as hordein from barley and gliadin from rye behaved like wheat gliadin. Indian corn contains proteins, among which are glutenin and zein, the latter constituting a little over half the protein in the corn. When corn glutenin was given as the protein in the rat's dietary, normal growth was recorded. However, when the alcohol soluble zein was given, the rats lost in weight and died unless a change in diet afforded relief. Zein is a protein which is like gelatin in that it contains no tryptophan. Such a protein can never form new tissue, nor protect body tissue from its normal wear and tear, so the rat must perforce succumb. The remarkable verification of this theory lies in the fact that the addition of the missing tryptophan to the zein diet of rats or mice, either greatly prolongs their lives or may even cause them to maintain their weight (Gowland Hopkins, Ruth Wheeler, 24 BASIS OF NUTRITION Osborne and Mendel). These experiments show- why corn proteins are not the physiological equiva- lent of meat protein in nutrition. Phaseolin is a protein found in the kidney bean and behaves like zein in nutrition, failing completely to maintain the body weight of the rats which have received it. It may, therefore, be considered a pro- tein lacking in some chemical unit. The New Haven investigators point out how a single protein like casein can cause normal growth involving the production of all the various body proteins, such as hemaglobin, other blood proteins, elastin, collagen, the keratin of skin and hair and so forth, and even the complex nucleo-proteins also. Casein does not contain glycocoll but glycocoll may be manufactured from it within the animal organism. The body cannot, however, make tryp- tophan from gelatin or from zein, hence these can never form body protein or be used in its repair. The proteins of rice and potatoes are scarcely known because Osborne has not yet analyzed them. Enough has been said to give the reason why meat proteins are of greater physiological value in the diet of man than are vegetable proteins. It is evident, however, that if enough bread or enough corn be taken, a sufficient quantity of their content of the more valuable proteins will be obtained. The ox merely takes these miscellaneous and variably constituted proteins and rearranges their constit- CONSTANT NEED OF PROTEIN 25 uent units into his own flesh, which is in composi- tion approximately like our own. In like manner the cow forms casein, a complete food protein, avail- able both for maintenance and growth. Protein is usually taken in excess of that bare requirement which is measured by the quantity necessary to repair the tissue. This excess is oxidized and used as fuel just as are fat and carbo- hydrates. Protein has one property out of all pro- portion to that possessed by the other food stuffs : it very largely increases the production of heat in the body. Individuals maintained on a low protein diet may suffer intensely from the cold. A good piece of beefsteak or roast beef will put the heat produc- tion on a higher level, and a person going out of doors on a cold day after a meal high in protein does not feel the cold. For the same reason, on a hot summer day, meat will be avoided. One may cause the heat production of a dog to double by giving a large quantity of meat. This action is due to the fact that many of the chemical units produced in the digestion of meat act to stimu- late the heat production in the animal. Some of these individual chemical units of which protein is composed have been fed to a dog and have been found to increase the heat production in the same way as does ingested meat. Glycocoll is the simplest of these units. It causes a great rise in heat pro- duction. In diabetes ingested glycocoll is completely 26 BASIS OF NUTRITION converted into sugar without undergoing oxidation. When thus given in diabetes glycocoll still causes an increased heat production although it is not oxidized. Hence it acts as a chemical stimulus and not in virtue of its energy content. This heat-increasing property of protein has been called its specific dynamic action (Rubner). This action may be effected by all kinds of proteins, by those of meat, fish, eggs, milk, and such incomplete proteins as gelatin. To obtain the warming effect it is not necessary to purchase beef, a relatively costly article of diet. The quantity of protein desirable in the dietary- had best be given consideration after discussion of the dietary habits of mankind. It is sufficient for the present to realize that protein is necessary to maintain tissue in repair, to promote growth and that when taken above the requirements for these purposes it stimulates the organism to a higher level of heat production. IV HABITS OF DIET There is a wide diversity of dietary habits in dif- ferent parts of the world. The inhabitants of the tropics live from the fruits which grow readily without especial cultivation. There being no reason to work hard for food and lodging, there is no in- centive to struggle and no advance in civilization. The struggle for food and lodging in the zones of moderate temperature has strengthened the body and mind of man. The food of the temperate zones is usually a diet containing a mixture of animal and vegetable substances. A race of human beings which is practically car- nivorous in its habits is the Eskimo. Recent studies (August and Marie Krogh : A Study of the Diet and Metabolism of Eskimos, Copenhagen, 1913) show that the Eskimo hunter may rise early in the morn- ing, drink a cup of water, of soup or of coffee. He then goes out without food or he may take a small bit of dried or frozen meat. Returning at three or four o'clock in the afternoon he fills himself with meat to his utmost capacity as soon as it can be cooked. He then sleeps for two hours, after which he enjoys himself socially and before retiring for 28 BASIS OF NUTRITION the night takes a second smaller meal, usually of fish. The principal articles of diet are seal meat and the meat of reindeer, walruses and whales. The skin of young whales is esteemed a delicacy and this has been found by Bertelsen to contain a very large quantity of animal starch (glycogen). The only native vegetables are whortleberries, young shoots of angelica, and seaweed which is eaten with mussels. When game is plentiful large quantities of meat and fat are eaten. Rink reports that young robust people may ingest as much as four kilograms (9 pounds) of meat daily during the time when seals are plentiful. In this way the Eskimos store ample fat in their bodies. Although this people are the greatest meat eaters in the world there is practically no gout among them. Also there is no quarreling. If two persons do not like each other they simply move away from one another, but a blow is never struck. They have great capacity for physical endurance and for resistance to external cold. On sledge journeys in the north during the winter when the temperature is — 30° C, they may take a full meal of frozen meat and blubber at night. The first result is a feeling of extreme cold and shivering, but after half an hour the stimulating effect of the large absorption of protein (meat) upon the heat produc- tion makes itself felt and the Eskimo may then HABITS OF DIET 29 sleep in the open with no other extra protection than his sled which is put up as a shield from the wind. The same kind of food is also taken by the dogs accompanying the party. If one turns from the carnivorous Eskimo to the population of India, China, Japan and the Philip- pine Islands, one finds that the great staple of diet is rice. Rice is a material which is almost tasteless in itself but which can be prepared in many ways and may be eaten with many diverse flavors. The poorest families of Southern India live essen- tially on rice to which is added a small quantity of fish. Rice can be raised with little effort but poverty excludes meat from the diet. McCay (The Protein Element in Nutrition) states that it may be accepted that these rice-eating inhabitants of Bengal, whose diet is poor in protein, are incapable of performing a really hard day's work, the explanation being an incomplete development of muscular tissue. It seems that the tropical heat of India yields nourish- ment as freely as it may be obtained in Greenland by the Eskimo, yet physical power is lacking in the inhabitants of the country. Among the hill tribes of India and wherever else animal protein is taken with rice, a higher physical development is found. The poorest Philippinos also live mainly on rice but they add sufficient fish to furnish an adequate diet. Aron (Philippine Journal of Science, 1909) 30 BASIS OF NUTRITION estimates that the daily cost of this diet per person in the town of Taytay amounts to 12^ centavos or 6^4 cents. The most celebrated European standard diet is that of Voit designed for a laboring man working hard during a period of nine or ten hours. This diet contains 118 grams of protein, 56 grams of fat and 500 grams of carbohydrates. Of the 118 grams of protein, 46 are furnished in 230 grams (one-half pound) of butcher meat. The quantity of meat in the ration was determined from the finding that each inhabitant of Munich consumed daily an average of 205 grams of meat and 25 grams of fowl and fish. The other factors were determined by statistics and they were verified by examining the diets of various laboring men. The quantity of fat was put low in the diet on account of its cost. Volumes have been written concerning the neces- sity of the quantity of protein in Voit's dietary. Voit, himself, showed that a man could exist with half that quantity but in the violent debate that centered around this question Voit took no personal part. When comparison is made of the diet of the Eskimo, the Bengali and the laboring man in Europe, the following distribution of the various nutritive elements is found. HABITS OF DIET 31 Calories in fo Weight Protein Total Carbohy- in kgrn. grams calories Protein Fat drates Eskimo 65 282 2,604* 44 48 8 Bengali 50 52 2,390 9 10 81 European .... 70 118 3,055 16 17 67 The figures regarding the Eskimo are taken from Krogh, who believes that they are not 10 per cent from the actual values. The carbohydrate reported is largely that of the glycogen content of the flesh eaten. The Eskimo takes five times the amount of protein eaten by a Bengali and two and a half times the amount eaten by a European. Yet he lives without acquiring uric acid diseases (Krogh). The specific dynamic action or heat- stimulating property of protein, as well as the Eskimo's coat of subcutaneous fat enables him to bear extremes of cold. The acidosis which arises when large quantities of fat are ingested without carbohydrates, is in all probability counteracted by a large production of sugar from the fragments of broken down protein. The production of sugar from glycocoll has been remarked upon and serves as a typical illustration of this process. Health and strength, therefore, are not wanting when in the Arctic regions a carnivorous diet is the mainstay of life. ♦Statistical average. The quantity of seaweed and mussels eaten could not be controlled. 32 BASIS OF NUTRITION As regards the Bengali, it seems that his ration of rice and fish does not serve to maintain him in good condition, whereas his neighbors in the hills who partly live upon the flocks they raise are in much better physical condition. Voit's ration contains about four times the mini- mal quantity of protein necessary for the mainte- nance of life. Voit's dietary has been condemned as financially extravagant and even physiologically harmful. Evidently many millions of dollars could be saved in the army and navy were the protein of the ration cut in two. Rubner recently appeared twice before the German authorities to protest against such reduction. He believes that there should always be an excess of protein constructive material, so that if after physical exhaustion there is depletion of the glycogen reserves, under which circumstances the wear and tear on the cell protein is increased, there may be building units in reserve to quickly restore the tissue destroyed. For a laboring man to take the minimal quantity of protein in the diet is, therefore, not desirable. Meltzer has truly pointed out that eating protein in quantities above the minimal requirement is one of the many "factors of safety" in human life. Moreover, it would be a difficult proposition to arrange a low protein dietary for such laboring men as farmers, for example. Rubner points out that the staple diet of the robust and healthy Bavarian HABITS OF DIET 33 peasant has been milk, cheese, bread and vegetables, and this for many centuries. Such a diet, even though it contain no meat, is not a diet low in protein. On the Texas cattle ranches twenty years ago, although there were thousands of cattle, there was little fresh meat and never any milk. Fresh meat was considered too expensive. Coyotes destroyed the chickens, so eggs were not available. The staple foods were boiled beans, bacon (called sow-belly), soda biscuits, molasses, canned tomatoes, black coffee and a large dish of very greasy flour gravy. The proteins were therefore largely those contained in beans and wheat. The Texan cow puncher raised beef for the inhabitants of the cities but he rarely ate it himself. Yet no one could deny that he was not physically fit. A traveler on arriving at one of the ranch houses called out, "Hello, can I stay here all night ?" The answer was usually in the affirma- tive, and a passing stranger thus received was given the best in the house, always without money and without price, and when he departed was invited to "come again." The question may be asked about the relative value of beef, veal, mutton and chicken. These are frequently differentiated by the physician in pre- scribing for his patient. Experiments involving the ingestion of these various forms of meat give no information that one kind is more readily absorbed 34 BASIS OF NUTRITION than another. Chemical analysis shows no differ- ence. The substances which are convertible into uric acid are present in all these meat foods in about the same quantity. It resolves itself into a question of habit, personal taste and the local capacity to cook. In Germany, light colored meats such as chicken and veal are considered digestible and good food for the sick. Red meat like beef is deemed indigestible. A German professor of medicine re- marked in his lectures, "Curiously enough, in America, beef is considered digestible and veal very indigestible." Veal is well cooked in Germany and greatly liked. The cooking of beef, on the contrary, is one of their unsolved problems. These facts, remembered in connection with the great value of milk as a protein food, should be held in the mind of everyone who wishes to inflict his personal dietetic whims and fancies upon his long-suffering friends. Ultimately the question is a question of flavor. Man chooses what he likes best, and, taken in moderation, what he likes best he digests best. Hence the demand for meat, which is not necessary and which could be largely replaced by the cheaper and equally valuable protein of milk, or even by the proteins of wheat and of beans taken together. Rubner points out how the consumption of meat per head of population in Germany has risen three and a half fold during a hundred years and now approximates that consumed in England and in the HABITS OF DIET 35 United States. In 1813 the consumption of meat in Germany per inhabitant was about at the level of that in Italy today. The large use of meat has come with the concentration of population in the cities. The same transformation has taken place in the United States. In 1820 only 5 per cent of the popu- lation lived in cities of 8,000 and over, whereas, in 1910, 33 per cent lived in such cities. This third of the population demands meat in increasing quantity despite its increasing price. V THE CURIOUS DISEASE OF BERI-BERI It has been known for a long time that life cannot be maintained on an absolutely pure mixture of salts, fats, carbohydrates and protein. Osborne and Mendel could not prepare a diet which was chemi- cally pure in all its constituents and still maintained life. In most of their successful experiments the ash of the diet was derived from a powder obtained by evaporating milk, the protein content of which had been almost entirely removed. They have recently reported experiments on rats in which growth had come to a standstill when the fat in the diet consisted of lard, but in which rapid growth ensued when butter fat was substituted for lard. Butter fat must therefore contain something which lard does not contain. The human organism is extremely sensitive to certain substances in minute quantities. Thus, epinephrin, the active constituent of the suprarenal glands, is present in the blood in 1 part in 100,000,- 000 and this is essential to life. One may also recall the marked influence on growth exerted by the thymus gland during youth. How profoundly important the secretions of the internal glands may THE DISEASE OF BERI-BERI 37 become has been vividly demonstrated by Guder- natsch, who gave tadpoles thymus gland and noted their rapid growth and delayed metamorphosis, whereas when thyroid gland was given suppressed growth and premature metamorphosis into pigmy frogs took place. The profound effect of small amounts of materials formed in the various internal glands is well established. However, it has only recently appeared probable that, in order to maintain the organism in condition, a small quantity of something not hereto- fore recognized must be present in the food. Eykman, in 1897, called attention to the fact that the disease beri-beri was prevalent among those rice- eating nations which partook of rice prepared in a certain way. The Bengali eats unpolished rice, that is, rice of which the red husk or pericarp has not been removed and he does not suffer from beri-beri. When the native of the Philippines pounds his rice in a large mortar with his own hands, the milled product is never so thoroughly freed of its husk as happens to that milled by machinery and hence these natives are partly protected from the disease. A diet which is based almost exclusively on white rice causes beri-beri with certainty. Eykman also found that when chickens or pigeons were fed on white rice they developed a disease similar to beri-beri. General weakness, with paralysis of the legs and wings, due to a polyneuritis, developed, which could 38 BASIS OF NUTRITION be cured by a change in diet. Here, fortunately, were experimental animals which could be used as a means of finding a cure for the trouble. Un- polished rice, or polished rice when meat or beans were added to the diet, did not induce the disease. Polished rice given with rice polishings prevented the disease. It has been stated that in Irish and sweet pota- toes, and in many common breakfast foods, there is not enough neuritis-preventing substances preient to preserve health. Also meat, when sterilized at a high temperature, loses these materials. The desira- bility of sterilization by boiling of milk for infants has recently been questioned by Funk on account of the liability to destruction of these anti-neuritic substances. Funk has sought to isolate the substances which prevent beri-beri, which he has termed the vita- mines. From 100 kilograms (220 pounds) of dry yeast he prepared 1.6 grams of a crystalline sub- stance which, if given in doses of 4 to 8 milligrams to neuritic pigeons, cures them in from two to three hours. This substance on purification yielded three materials called Substance I, Substance II and nico- tinic acid. Substance II was inactive. Substance I and nicotinic acid were severally of little value in curing the polyneuritis of pigeons, but when 3 milli- grams of the one and 2 milligrams of the other were administered together, the diseased pigeons were THE DISEASE OF BERI-BERI 39 cured in two to four hours. Rice polishings yielded these same two substances. It therefore appears that a class of vitamines exist in the vegetable kingdom, and that these are neces- sary to the normal growth and nutrition of animal tissue. They become a part of animal tissue, so that if meat be eaten, their direct ingestion from the plant becomes unnecessary. They enter into normal milk. If the nursing mother has beri-beri the infant acquires it also. The authorities consider scurvy, the Miiller- Barlow disease, and possibly pellagra and rickets as of analogous origin. Finally, in this connection, it is well to utter a warning to the effect that beri-beri and scurvy do not occur in the United States. They only occur when a one-sided diet deficient in vitamines exists. It is well to remember that the American Associa- tion of Tropical Medicine, in May of this year, denounced legislation in the United States against polished rice as unnecessary. Dr. W. P. Chamber- lain, Major, Medical Corps, U. S. Army, who worked experimentally on this subject for two years in the Philippines and saw the disease entirely dis- appear among the Philippine Scouts, advises against any such legislation, and states that the advocacy of unnecessary' legislation weakens the authority of the medical profession upon sanitary matters. It has thus far been shown that nutrition means 40 BASIS OF NUTRITION fuel for the machinery, new parts with which to repair the machine and minute quantities of vita- mines which produce a harmonious interaction between the materials in the food and their host. VI CRITERIA OF THE MONETARY VALUE OF FOODS The daily press five months ago contained col- umns of matter regarding the high price of food materials. Not only foods but commodities in general were at the highest prices in thirty years. Some idea of the rise in food prices is indicated below. Increased cost Increased cost in per cent in per cent on Feb. 15, on Feb. 15, 1913, above 1913, above ave'ge price costoneyear 1890-99 in 39 before in N. cities, U.S.A. Y. City Sirloin steak 61 17 Round steak 85 18 Rib roast 63 17 Pork chops 89 24 Smoked ham 69 13 Pure lard 62 10 Hens 67 8 Wheat flour 27 10 Corn meal 56 Fresh eggs 63 18* White potatoes 24 no data Fresh milk 40 1 Since the efficiency of labor depends upon its energy and constant repair, it is certainly of no ♦Decrease. 42 BASIS OF NUTRITION small moment that the citizen should know how best to maintain the machine at a maximum of effi- ciency. Not only that, but in times of trouble he should know where to turn to find nourishment in the form which is best and cheapest. Who will give him this information? Will the manufacturer of canned tomatoes tell him that tomatoes are valueless in his extremity? No, not unless the manufacturer is forced to do so. And how can the manufacturer be forced to give this information? By being compelled by law to label his can: "This can contains x calories of which y per cent are in proteins of grade C." (Consult also Murlin, Popular Science Monthly, October, 1913.) If, through the medium of the schools and the press, everyone knew that a man of sedentary occupation required 2,500 calories and a laboring man 3,000 calories and more, no one suffering from want would spend his money for a can of tomatoes which is little else than flavored water. It has been estimated that a family of five, includ- ing the father, a clerk, the mother who does the housework, and three children, nine and six years and one month old respectively, requires 7,750 cal- ories per day. (Lusk: Food at Fifty Cents a Day, New York Evening Post, February 8, 1913.) This is probably within 10 per cent of the true value. To provide a diet containing 7,750 calories, 5 per cent of which were in animal proteins of grade A MONETARY VALUE OF FOODS 43 and 10 per cent of which were in vegetable proteins of grade C (bread), would have cost as follows on January 28, 1913, in the New York markets : Cents Bread -f- % pound salt cod 4/ Bread + % pound smoked ham 48 Bread -f- % pound cheese 51 Bread -f- 2]^ pounds milk S3 Bread + P/2 pounds loin pork 56 Bread + 1% pounds leg of mutton 56 Bread + Hi pounds cod steak (fresh) 58 Bread -f- 1% pounds sirloin beef 66 Bread -f- l 1 ^ pounds turkey 78 If cornmeal, oatmeal, dried beans or rice had been used instead of bread, these prices would have been lower, whereas potatoes would have slightly increased them. These figures are for the great staples of diet. It is obvious that the cost of fuel for an adult requiring 2,500 calories would be one-third the cost for the family or an amount not exceeding twenty cents a day at the market price of the fresh mate- rials. This being true of the staple products of a dietary, it is obvious that when more than an aver- age of eight cents is expended for 1,000 calories of nutriment, the diet must include luxuries. The following represents the market price in cents of 1,000 calories in various staple foods: 44 BASIS OF NUTRITION Cost in Cents of 1,000 Calories Glucose 1% Cornmeal 2 Wheat flour 2% Oatmeal 2% Cane sugar 2>% Dried beans 4 Salt pork (fat) 4% Rice 5 Wheat bread 5% Oleomargarine 7 l /h Potatoes TVi Butter 10 Milk 10 Smoked ham 10% Cheese 11% Loin pork 12% Mutton (leg) 16% Salt cod 1944 Sirloin beef 24 Turkey 40 Codfish steak (fresh) 42 This is the cost of nutritive values and when con- sidered in relation to the preceding table, which in- cludes the proper amount of protein for a family, is of the greatest economic importance. It is evident that if each package of food were sold as containing a stated number of calories, the widely heralded "food value" of Postum, for exam- ple, would "fold its tents like the Arabs and as silently steal away." Cost in cents iinimum Maximum 50 70 100 140 150 210 MONETARY VALUE OF FOODS 45 If the family of five, before mentioned, keeps a sen-ant the amount of food increases from the equivalent of 7,750 calories to 10,250, an increase of 30 per cent. Three servants will double and six servants treble the food bill. One can thus formu- late the household requirements : Calories Poor family 7,750 Well-to-do 15,500 Wealthy 23.250 Whatever is spent above these amounts is paid for waste or for non-essentials in the form of flavors of high price. High cost may also be due to car- nivorous indulgence approximating that of the Eskimo. The variant introduced by indulgence in meat may be thus illustrated : Daily cost in cents to furnish Poor Well-to-do Wealthy All the calories are in family family family Wheat bread 41 82 123 Sirloin steak 186 372 558 Eggs 258 516 774 Turkey 312 624 936 (0 servants) (3 servants^ (6 servants) It is not probable that the food values actually consumed are very different in the various well- 46 BASIS OF NUTRITION nourished families. Only the cost can vary enormously. The cost of eggs in the above table is estimated at the low figure of 24 cents a dozen. At the present moment with the cost of fancy fresh eggs at 75 cents a dozen, it would cost the wealthy family $24 a day if its sustenance were solely derived from eggs. To support the three differently conditioned families on eggs alone would require 129, 258 or 387 eggs daily. Where there is surplus income and financial limi- tations do not hamper the expenditure for food, the subject-matter of this paper has no practical bearing. When each individual can partake of nourishment in accordance with the dictates of a. normal appetite there is no danger of undernutrition. It is, how- ever, among the poor, the class to which scientific knowledge is the last to reach, that such knowledge would be most valuable. Recently, Miss Dorothy Lindsay made a report concerning the diet of the working classes in Glasgow. Noel Paton, in his preface to the report, asks this important question, "If a suitable diet is obtainable and is obtained, is it procured or can it be procured, at a cost low enough to leave a margin sufficient to cover the other necessary expenses of family life, with some- thing over for those pleasures and amenities without which the very continuance of life is of doubtful value?" Miss Lindsay examined the dietary habits of sixty MONETARY VALUE OF FOODS 47 families whose incomes varied from $3.25 to $15.00 weekly. Wherever the wage was above $5.00 a week the family was adequately nourished and the man of the family received 3,000 calories daily, that is to say, enough to make him an efficient ma- chine. "Where the wage fell below $5.00 a week there was always undernutrition. The staples of food were bread, potatoes, milk, sugar, beef and vegetables. Little use was made of cheaper oatmeal, peas, beans, cheese or fish. Oatmeal was used in forty-six out of sixty families, but the average amount per man per day was less than one ounce (less than 100 calories). The amount spent for food varied between 62 and 87 per cent of the total wage. In the families showing an average of 87 per cent expenditure for food, the father was a drinker and the family in debt for the rent. It was found that when the weight of a child at a given age was much below the normal, inadequate diet was almost always the cause. Miss Lindsay con- cludes that one of the main contributing factors of malnutrition among the poor is bad marketing. The experience of America in the matter of school lunches for the children of the poor, has shown so marked an improvement in their physical and mental well-being, that it is reported to be of demonstrable economy to the state to feed the undernourished children. But the state should also teach the mother the value of bread and milk, and 48 BASIS OF NUTRITION that weak tea cannot take the place of milk in the nourishment of the child. Recently F. C. Gephart of the Russell Sage Insti- tute of Pathology has undertaken a study into the physiological value of the various portions of food sold over the counter of the Childs restaurants in this and other cities. All the New York restaurants of this company have been visited and of those in the entire country about 70 per cent. This is not the time to give more than a few general statements regarding the results. For obvious reasons, no knowledge of the work has passed beyond the con- fines of the laboratory circle. Samples have been analyzed for protein, fat and carbohydrate ; in some instances also for ash, and the heat of combustion has been determined in each case. Four hundred samples in all have been collected and analyzed. For comparative standards the calories in bread and vintage champagne have been selected, neither of which was purchased in the restaurant. The fol- lowing table shows a few of the results : MONETARY VALUE OF FOODS 49 Food Value of Portions, in Childs Restaurants, Including Bread and Butter When Served a Calories 9! 1)