The Story of Nutrition

ELIZABETH NEIGE TODHUNTER

THIS is the story of man's long of physics, medicine, agriculture, and search for exact knowledge of biology. the food his body needs. Because it is a ''new" science, then, It is a story of laboratories, experi- let us begin with the man who has ments, failures, successes, and dis- been called *'the father of American coveries. It is even more a story of men nutrition" and later go back to the and women with curiosity, ideas, per- men and ideas that preceded him—for sistence, and a driving desire to help nutrition, like every science and almost people live better. every other great development, has It is a story of a ñght against igno- been built on things that went before. rance and superstitions and the strange Wilbur Olin Atwater was born in ideas people always have had—now, 1844 in Johnstown, N.Y. He attended too !—about the things they eat. the University of Vermont and Wes- It is an old story that could begin leyan University in Middletown, with the first man and the little he Conn. For his thesis for his doctor's knew beyond the fact that he liked to degree at Yale University in i86g eat. he—for the first time in this country— It is, though, primarily a story of used modern methods to analyze corn accomplishments in this century— fodder. indeed, in the last few years; a story He went to Europe in 1869 to study so new that it is far from its end. agricultural and physiological chem- Although for centuries people tried istry at the Universities of Leipzig and to solve some of their problems of what Berlin. When the first experiment sta- to eat and how much and why, they tion in the United States was estab- made little progress until chemistry lished at Middletown in 1875, ^^ was well developed and we could became its first director. He later analyze foods and know what they are became director of the Connecticut made of. We also had to wait until Agricultural Experiment Station at physiology became a science that Storrs when it was organized in 1887. could provide understanding of the His studies on the acquisition of human body and how it functions. We atmospheric nitrogen by plants and on needed as well the contributions the composition of feeds, begun several TEARBOOK OF AGRICULTURE 1959 years earlier, he continued as part of of Experiment Stations under Dr. the work at Storrs during the 14 years Atwater, who was designated "chief he was director. These investigations of nutrition investigations." led to his interest in the composition of From that time forward, biochem- man's food. ists, nutritionists, home economists, Dr. Atwater made a series of analyses and investigators in animal and poul- of fish for the United States Fish Com- try husbandry at agricultural experi- mission and of the flesh of domestic ment stations throughout the country animals for the Smithsonian Institu- have steadily and continuously helped tion between 1879 ^^^ 1883. He con- build the newer knowledge of nutrition. ducted studies of the dietaries of people Headquarters for the work were in Massachusetts and Canada. established at Middletown, and Dr. Dr. Atwater returned to Europe in Atwater was made chief. He and his 1887. He worked in the laboratory in colleagues investigated the diets of Munich where Carl Voit was doing hundreds of persons of different occu- outstanding work in studies of respira- pations and compared the results of tion—the exchange of gases between similar studies in other countries. They the blood and the tissues—and calo- made many experiments with men on rimetry, the measurement of heat, the digestion and carried on special studies first steps toward quantitative knowl- of the nutritive value of cereals, meats, edge of nutritional requirements. vegetables, fruit, and nuts and the Another American student who effects of cooking and other forms of worked in Dr. Voit's laboratory was preparation on nutritive values. Graham Lusk, who brought back with He and his coworkers demonstrated him a small model of a calorimeter that the amount of heat—energy—a Voit had made and later built others person develops during a given period at Cornell University Medical College is the amount that can be derived from in New York City for studies with the energy liberated in the oxidation dogs and children. We shall come back of food materials during the period. to Dr. Voit later. Dr. Atwater studied digestibility of Dr. Atwater also returned to this food, made numerous dietary studies, country inspired to do further calorim- and analyzed many foods. He pre- etry studies at Wesleyan University. pared in 1896 the famous Bulletin 28 With his coworkers be built a calorim- of the United States Department of eter for studies on man and designed Agriculture. It was the first extensive a bomb calorimeter for measurement table of food values ever prepared in of caloric value of foods. He made ad- this country. justment for the indigestible fraction Atwater sought to find what was the in food and the incomplete oxidation best and most economical diet for of protein in the body and gave the man. At that time only protein and values, widely used ever since, of 4, 9, Calories, as supplied by fat and carbo- 4 Calories per gram of carbohydrate, hydrate, were considered of impor- fat, and protein in a mixed diet. tance, and such foods as green, leafy The Congress in 1894 appropriated vegetables and fruit were regarded as 10 thousand dollars "to enable the expensive purchases or luxuries. Secretary of Agriculture to investigate A chapter Dr. Atwater wrote for the and report upon the nutritive value of 1894 Yearbook of Agriculture has the various articles and commodities meaning for us today. I quote a few used for human food, wdth special sentences from it: suggestion of full, wholesome, and "Materials for the food of man make edible rations less wasteful and more up the larger part of our agricultural economical than those in common production and the largest item of our use." export abroad. Our food production This work was assigned to the Office is one-sided. It includes a relative THE STORY OF NUTRITION excess of the fat of meat, of starch, and in the less expensive materials. . . . of sugar, the substances that serve the The maxim that 'the best is the body for fuel to yield heat and muscu- cheapest' does not apply to food." lar power, while the nitrogenous sub- stances, those which make blood and LET US GO BACK now for a glimpse muscle, bone and brain, are relatively at the beliefs and knowledge on which deficient. . . . What is needed is Atwater and other scientists of the 20th more nitrogen in the soil for plant century built. Such a quick survey food, more nitrogen in plants to make will help us to understand better the better food for animals and man, and growth of the science of nutrition— more nitrogen in the food of man. and the speed with which it has grown. Better culture of the soil and bet- Back in the days of the Greeks, ter manuring will bring not only before the birth of Christ, man's larger crops, but crops richer in inquiring mind was asking questions nitrogen. . . . about the world in which he lived. "The power of a man to do work The "science" of that day believed depends upon his nutrition. A well-fed that there were four elements—earth, horse can draw a heavy load. With air, fire, and water; four qualities— less food he does less work. A well-fed dry, cold, hot, and wet; and four man has strength of muscle and of humors, or liquids, that comprised brain, while a poorly nourished man the body—blood, phlegm, black bile, has not." and yellow bile. He defined food as "that which, Hippocrates, the father of medicine, when taken into the body, builds up its taught the value of diet, but he tissues and keeps them in repair, or believed in one universal aliment, an which is consumed in the body to idea that prevailed until the early yield energy in the form of heat to part of the 19th century. keep it warm and create strength for Galen, a Greek physician who settled its work. ..." in Rome in A.D. 164, wrote many "The most healthful food is that books about anatomy, diet, and which is best fitted to the wants of the health. His word was accepted without user. . . . question through the centuries that "The cheapest food is that which saw the decline of Rome, the Dark furnishes the most nutriment at the Ages, and the first light of the Renais- least cost. sance, until Andreas Vesalius (1514- "The most economical food is that 1564), a Flemish student of anatomy, which is both most healthful and overthrew some of Galen's ideas and cheapest. dared to investigate for himself, rather "To make the most out of a man, to than follow blindly the master's dicta. bring him up to the desirable level of One original thinker in Italy tried to productive capacity, to enable him to study nutrition. He asked the right live as a man ought to live, he must be questions, but he could not get the well fed. answers because he had neither a "One of the ways in which the worst knowledge of chemistry nor the neces- economy is practiced is in the buying sary tools. Santorio Sanctorius (1561- of high-priced foods. For this error, 1636) day after day sat on his big bal- prejudice, the palate, and poor cook- ance and weighed himself and the food ing are mainly responsible. There is a he ate, but could not find the answer prevalent but unfounded idea that to the difí'erence in weight after he had costly foods, such as the tenderest eaten. He has truly been called the meats, the finest fish, the highest father of experiments in metabolism, priced butter, the choicest flour, and but it was some 300 years later before the most delicate vegetables possess investigators could explain the nutri- some peculiar virtue which is lacking tion problem he had posed. 10 TEARBOOK OF AGRICULTURE 1959 In the 17th century, "the Golden Lind, conducted a carefully controlled Age of Science," the experimental experiment, the first of its kind, and method began to take hold. The Brit- demonstrated how to prevent and cure ish William Harvey revolutionized our scurvy, "the scourge of the sea," that concept of the human body by dem- killed hundreds of sailors on ships tak- onstrating that blood circulates from ing long voyages. Dr. Lind in 1747 the heart throughout the body. The found that lemon juice could cure or Dutch Anton van Leeuwenhoek de- prevent this disease; yet it was more veloped the microscope and studied than 50 years later before the British the red cells or corpuscles of the blood Navy required that lemon juice be stream. At meetings of the Royal So- provided on all ships. Even then no ciety, which received its charter in one seemed to realize the significance 1662, scientists discussed their experi- of the cure; some 150 years later vita- ments and the curiosities of nature min C was discovered as the anti- they had found. scurvy vitamin. The 18th century brought the rise of The 19th century was the period of modern chemistry. Joseph Black, a chemical investigation and measure- professor at Glasgow, discovered the ment of respiration and energy use by gas that to us is carbon dioxide. animals. Wealthy, eccentric Henry Cavendish Hippocrates had taught that there discovered hydrogen. Daniel Ruther- was one ultimate principle in food, ford, a Scottish physician, discovered and not till 1834 did this idea change. nitrogen. Joseph Priestly, the English William Prout, a London physician, minister who was happiest when he published a book, Chemistry^ Meteorol- was in his laboratory, was credited ogy and the Functions of Digestion, in with discovering oxygen. which he put forward the idea that Antoine Lavoisier of France, out- food contained three staminal princir standing in his ability to interpret and pies, which he called saccharine, oily, integrate the new discoveries, showed and albuminous material. that the life process is one of respira- A new era began in 1816 when tion and that as oxygen was consumed Francois Magendie, the great French by the body, carbon dioxide was ex- physiologist, discovered that dogs died haled. He measured those gases and if given only sugar or oil or butter but calculated the body's heat production. would live if given a nitrogen-contain- He realized that the working man ex- ing food. Soon Jean Boussingault, pended more calories and therefore a French chemist and experimental needed more food than those who were farmer, made the first experiment of less active. nitrogen balance with a horse and a Interest in physiology grew. René cow. Gerrit Jan Mulder, the Dutch Reaumur (1683-1757), a French nat- physician and chemist, exploring the uralist and physicist, fed various foods nitrogen-containing foods, introduced to birds and then, after short periods of the term "protein" in 1838. He was time, retrieved the food and studied wrong in what he thought these pro- the changes that had taken place dur- teins w^ere, but the name stuck. ing digestion. The chemistry of the albuminous Lazzaro Spallanzani (i 729-1799) in (protein) substances, as these were Italy experimented on himself. He first called, began to be understood swallowed linen bags containing meat when some of the "building units" and bread and withdrew them later by of these complex substances were iso- strings attached to the bags. From the lated. The first amino acid, cystine, changes he found in the partly di- was discovered in 1810 by the English gested food, he realized that some chemist and physicist William WoUas- chemical changes were taking place. ton when working with kidney stones. A Scottish naval physician, James He failed to recognize its true chemical THE STÖRT OF NUTRITION II nature. The simplest of all the amino hole let Dr. Beaumont have a living acids is glycine. It was first identified organ for the study of digestion. Pa- by M. H. Braconnot, the French tiently and accurately, he made his chemist who obtained glycine as a experiments so that the findings pre- breakdown product from hydrolysis sented in his book. Experiments and of gelatin. Observations on the Gastric Juice and the By the end of the 19th century, 12 Physiology of Digestion (1833), were of the 22 amino acids now known to unsurpassed until the researches of be present in proteins of food had the Russian physiologist, Ivan Petro- been discovered. vich Pavlov. The spotlight was on protein. Or- Dr. Beaumont might have accom- ganic chemistry developed, and Justus plished more, but Alexis did not like von Liebig, the great German chem- being experimented with. He slipped ist, branched out to develop the new away to Canada and declined to re- agricultural chemistry that was later turn. Chemistry was not far enough to lead to biochemistry. advanced in Beaumont's day to be Studies of nitrogen balance were able to identify what was in the sample made on dogs and other experimental of gastric juice that he sent to the lead- animals in attempts to determine the ing chemists to analyze. But digestion amount of protein they needed. Chem- was clearly recognized now as a chem- ists were busy improving methods of ical process of breaking down food, food analysis, and the general belief and men could begin to find out what was that through knowledge of chem- it involved. ical composition of foods one would Next came the study of respiration be able to plan an adequate diet. and calorimetry that led to the meas- The French chemist Jean Dumas urement of man's energy needs—the evolved an accurate method for quan- first steps to quantitative knowledge of titative measurement of nitrogen. The nutritional requirements. protein content could be calculated Foremost in this work was Carl Voit, from it. But it was such a long, pains- who had learned his chemistry from taking process that not many studies Liebig and later provoked his former could be made. Then the keen mind of teacher by daring to disagree with Johann Kjeldahl, a Danish chemist, some of his findings. devised a new and relatively easy Voit, with the help of Max von Pet- method of determining nitrogen in tenkofer, who had been Liebig's as- organic matter (1883), and the work sistant, built an apparatus for the study could push ahead more rapidly. The of respiratory exchanges in man and availability of equipment and suitable animals. Between 1866 and 1873, these chemical methods of analysis have two men published seven long papers always been an influencing factor in on the metabolism of healthy persons the development of the science of during fasting and at work. Dr. Voit nutrition. showed that, contrary to current be- lief, nitrogen metabolism is not in- IN AMERICA, physiology and the creased by muscular work. study of digestion of food were aided One of the greatest of all Voit's pu- by the work of a backwoods surgeon, pils was Max Rubner, who continued William Beaumont. He was on Army the calorimetry studies begun under duty at Fort Mackinac in Michigan his master teacher. He determined Territory when a gunshot wound of a caloric values of 4.1, 9.3, and 4.1 per French Canadian trapper, Alexis St. gram of carbohydrate, fat, and protein. Martin, gave him an opportunity to Rubner also established the law of show his medical and surgical skill. surface area in basal metabolism from The trapper's life was saved, but he his experiments, which showed that lived with a hole in his stomach. The heat production of man in the resting TEARBOOK OF AGRICULTURE 1959 State is proportional to the surface area vent beriberi, which took the lives of of the body. He showed that the law many Japanese sailors, by increasing of conservation of energy—which says the amount of meat and fish in their that energy must have a source: it can- diets. not come from nothing, nor can it dis- Nicolai Lunin, a young student in a appear into nothing; it only changes Russian laboratory, found in 1880 that form—holds true for the animal world mice thrived on milk, but they died if as for the physical. Rubner also dem- they were given a mixture of protein, onstrated that fat and carbohydrate fat, sugar, and ash of milk. These are interchangeable in nutrition on the findings could not be explained and basis of energy value. attracted little attention in a world An entirely different concept of food that was making rapid progress in values was introduced some 20 years chemistry and bacteriology. The time later. was coming when the limited view- Elmer V. McCollum in 1918 pub- point provided by chemical analysis lished a book, The Newer Knowledge of would be replaced by the new biologi- Nutrition—a title that was used by cal method. many w^orkers from then on to de- scribe the change which had taken VITAMINS now are household words, place in our understanding of nutri- but the term was coined only in 1912 tion. In that book, Dr. McCollum also by a Polish chemist who was working introduced a term that has been at the Lister Institute in London. widely used ever since—*'the protec- Casimir Funk was trying to isolate tive foods." Milk and the leaves of some substance from rice polishings plants, he wrote, are to be regarded as that would forestall beriberi. He rea- protective foods and should never be soned that if there was something omitted from the diet. in food that prevented beriberi, scurvy, The rapid growth of knowledge of and pellagra, this something was vital nutrition in the 20th century is also for life. illustrated by the book. The first edi- His laboratory preparation, which tion in 1918 had 189 pages. It went w^as effective in curing beriberi in through five editions, and the latest in birds, was an amine compound, and 1939 had 684 pages. so he coined the name * Vitamine." The 20th century opened with the The name caught on. general recognition that protein, fats, Support was given to Dr. Funk's sug- and carbohydrates as sources of energy gestion of the existence of vitamines and some inorganic salts were the ÍDy the work of Frederick G. Hopkins, necessary components of the diet. biochemist in Cambridge University, This, despite the fact that some two England. Dr. Hopkins fed rats an arti- centuries earlier, Dr. Lind had shown ficial diet prepared from constituents that because lemon juice would cure of the same nature as those present in scurvy there must be something else milk. He used a diet of casein, starch, in food. Other investigators some 10 cane sugar, lard, and inorganic salts, to 20 years earlier also had unusual each constituent as carefully purified tilings happen with diets they were as possible. The rats grew for a short using. Christiaan Eijkman, a Dutch time but then drooped and died. A army surgeon, discovered that chick- similar group of rats grew^ normally ens fed polished rice developed a when they were given as little as 2 neuritis, like beriberi, which he could cubic centimeters of milk daily in cure or prevent by feeding brown rice. addition to the artificial diet. He was the first person to produce a Dr. Hopkins showed that it was not dietary deficiency disease experi- a lack of calorics that caused the death mentally. In Japan, Baron Kanekiro of the animals, nor was it lack of Takaki had found that he could pre- palatability of the diet—a reason often THE STÖRT OF NUTRITION 13 given then to explain the failure of that he must experiment with the growth in animals on special diets. simplest of rations prepared from puri- He postulated that there were un- fied foodstuff's if he was to find the suspected dietetic factors, or accessory cause of the difi'erencc. Because a large food substances, that were essential for amount of foodstuff would have to be health. prepared and it would take a long time Louis Pasteur's brilliant researches for results to show up in cows, he of the 1870's helped establish the new decided he must use some small ani- science of bacteriology and fixed the mal. He chose the rat, and so started germ theory of disease firmly in the what was probably the first rat colony minds of scientists. and first extensive series of experi- Cleanliness and sanitation in the ments with these widely used test handling of food were recognized as animals. essential. But the idea that something By 1913 Dr. McCollum had found not present in food, something lacking, an artificial diet of protein, lactose, could cause disease was indeed difíicult starch, and inorganic salts, that, with to accept. Men's minds must be ready butterfat, gave good growth. If he used for the acceptance of new ideas and the same diet, but replaced the butterfat the findings of research; there was with olive oil or lard, the rats failed in much resistance to the vitamin theory growth and health. Some essential un- for a decade at least. known factor was thus shown to be Some experiments started at the present in butterfat. It was first called University of Wisconsin in 1907 were fat-soluble A and, later, vitamin A. to lead, by halting steps at first, to the Further study of the purified diets actual discovery of the first of the then being used disclosed that the lac- many vitamins with which we are tose was not "pure"; when it was familiar. Rations of the same chemical further purified, the rats developed composition, but each from a difi^erent polyneuritis, or beriberi, which could single plant, were fed to cows. The be cured by feeding a water extract of corn-fed animals were sleek, trim, rice germ. Thus water-soluble B— healthy looking after a year. Those vitamin B—was discovered. receiving the ration from the wheat Similar findings were reported al- plant had a rough coat and a gaunt most at the same time by Thomas Burr appearance. Those fed the oat plant Osborne and Dr. Mendel at Yale, and were midway between. The experi- so opened up the era of what Mendel ment proved that chemical analysis has called ''the little things" in did not give the complete answer nutrition. about nutritive values. Back in 1907, two Norwegian inves- Elmer V. McCoUum was one of the tigators—Axel Hoist and Theodor assistants in those early classic experi- Frölich—wanted to study what was ments with cows. He was a farm boy ''ship beriberi," which was common from Kansas with a thirst for knowl- among Norwegian seamen. They edge and a retentive mind, and he had tried to produce beriberi in guinea studied under the great Lafayette pigs. Like the Princes of Serendip, Benedict Mendel at Yale University. they found something other than what Dr. McGollum was given the assign- they were seeking. The diet used ment to try to find what was the cause produced scurvy in the guinea pigs, of the difí'erence in the three rations, and thus by lucky chance a suitable which were chemically similar, at test animal was found. They were able least according to the analytical to feed difí'erent foods and find which methods then available, although they ones -would cure scurvy. Once vita- gave difí'erent results. mins A and B were discovered, it was The young McCollum read and realized that the ''unknown" in fruit pondered. He came to the conclusion and vegetables must be another vita- TEARBOOK OF AGRICULTURE 1959 min, and vitamin C was added to the the vitamins to be isolated in pure list. form. It was later named ascorbic acid. The change in spelling, with the Soon others were isolated and iden- dropping of the final "e", was made tified chemically, their functions and in 1920, because it was realized that food sources studied, and the amount these unknown substances were not required daily for maintenance of "amines." health and vigor was determined. The nutritional deficiency diseases The old terms of "antiberiberi," "anti- scurvy and beriberi thus were known scorbutic," and so forth were dropped to be curable by proper food. What when it became apparent that the about rickets, pellagra, and pernicious vitamins did much more than just pre- anemia—would they, too, respond to vent disease. They were essential for a vitamin? health and well-being and functioned A pooling of knowledge gained from as part of many systems of the body. the early writers, clinicians, patholo- The latest discovery is vitamin B12 gists, experimental nutritionists, and (1948). It was found to be a preventive biochemists soon set the investigations factor for pernicious anemia, which of vitamins in high gear. had been described by Dr. Thomas More young scientists were being Addison about 100 years before. attracted by the new science of nutri- The vitamin story has developed tion and did their study under great mainly since the 1920's. Vitamins held teachers at Yale, The Johns Hopkins the spotlight, but many advances were University, Columbia, and Wisconsin. being made in our knowledge of pro- These young men and women went teins, trace elements, and other aspects forth to the colleges, universities, and of nutrition. experiment stations throughout the country to set up laboratories and to ONLY PROTEIN received much atten- continue the search for new nutrients tion at the beginning of this century. and the study of how they function. Dr. Atwater advocated 125 grams They encountered difficulties. The daily for a laboring man. Rubner had rats, guinea pigs, chickens, and dogs declared that a large protein intake with which they worked did not all was the right of civilized man, a view react in the same way, and soon many that was shared by many persons in letters of the alphabet were used up as temperate climates who enjoyed meat, designations for what were believed cheese, and eggs. Those who preferred to be new factors. a vegetarian or a more limited diet Vitamin D and vitamin E were strongly advocated a much lower in- identified. take of protein, and controversy raged By 1926, what had been called in the early decades. Later discoveries vitamin B was found to be at least two showed that the kind of protein was a separate factors. One was destroyed key factor, but we still hear of the early by heat and was the antiberiberi differences of opinion. factor. Another new substance was Russell H. Chittenden, first univer- stable to heat. sity teacher of physiological chemistry Each new discovery made it possible in this country, helped lay the founda- to prepare more highly purified diets tions of nutrition science through his and thus lead to more new discoveries, own investigations at Yale University as other deficiency symptoms showed and his training of many men. He pub- up in animals and the new curative lished in 1904 his revolutionary studies substances were sought—and found. of groups of athletes, soldiers, and pro- A young chemist, Charles G. King, fessional men who were maintained in at the University of Pittsburgh, in nitrogen equilibrium on what corre- 1932 prepared pure crystals of vitamin sponded to 44 to 53 grams of protein C from lemon juice. It was the first of for a man of average weight. THE STÖRT OF NUTRITION Slowly they learned that protein was quate to maintain life and promote not just protein—there are many dif- growth) and "incomplete"—that is, ferent proteins in food. Thomas Burr they lacked certain amino acids. The Osborne, a chemist at Yale, was a concept of quality as well as quantity leader in these studies. He learned that of protein thus was introduced. not all proteins are equally efficient in More amino acids were discovered. promoting growth or maintaining Nineteen were known then to occur in nitrogen equilibrium. food proteins. The next step was to find Karl Thomas, of Germany, intro- whether they were essential in the diet. duced in 1909 the term "biological Some were hard to get in pure form value" of protein and a formula for de- and in amounts sufficient to feed to termining it. Basically, the biological test animals. value of a protein means the percent- William C. Rose, one of Dr. Men- age of nitrogen retained by the body. del's students, by 1930 at the Univer- Comparisons of many proteins were sity of Illinois was able to combine the made in this way by feeding experi- 19 amino acids as the sole source of ments with animals and a few similar protein in diets for rats. The animals studies with human beings. failed to grow. Something was still The biological value of a protein was lacking. Because casein or gelatin seen to be related to the composition of added to the diet gave good growth, amincr acids in it. Frederick G. Hop- he concluded that some other amino kins at Cambridge University was a acid, rather than a vitamin or mineral, pioneer in these studies. He and Sid- was the missing factor. ney Cole in 1901 had discovered a new A search for the new amino acid be- amino acid, tryptophan. Later, when gan. It turned out that the new com- Dr. Hopkins and his coworkers fed pound was closely tied to another mice a diet with casein as the sole ni- amino acid, isoleucine, and so was trogen-containing constituent, the ani- difficult to separate and identify, but mals flourished. They died when zein, 4 years of patient work on the problem a protein from corn, replaced casein. finally yielded the answer. The new If tryptophan was added to the zein, amino acid essential for growth of rats however, the mice lived but did not was identified in 1934 and was named grow. "threonine" because of its close rela- Dr. Osborne was joined in 1909 by tionship to the sugar threose. Con- Dr. Mendel at Yale. They were "the tinuing his protein researches with most fertile combination of minds ever mixtures of pure amino acids. Dr. Rose directed toward studies of nutrition." was able by 1938 to prove that nine They studied almost every phase of were essential for normal rate of nutrition, especially protein and amino growth in rats. If arginine was omitted, acids, and conducted feeding experi- animals grew at about two-thirds the ments with rats that led to the discov- normal rate—an indication that the ery of vitamins A and B. They meas- organism would synthesize this amino ured the biologic value of isolated pro- acid but not at a rate that would per- teins and showed that amino acids mit normal growth. were the limiting factors. In history- Amino acids could then be grouped making experiments in 1915 they as essential and nonessential—needed showed that gliadin, a protein in and unneeded. The next step was to wheat, would maintain life but would find whether people needed these not promote growth in rats unless ly- amino acids. With young men as sine was added and that zein must be volunteer subjects, Dr. Rose learned supplemented with tryptophan and that eight of the amino acids are essen- lysine for life and growth. tial to maintain nitrogen equilibrium. At this time proteins were described He then set for himself the task of as being "complete" (they were ade- determining exactly how much of each i6 YEARBOOK OF AGRICULTURE 1959 was required each day. These were converted to niacin. Approximately the first long-continued series of studies 60 milligrams of tryptophan are equiv- in which human lacings were main- alent to I milligram of niacin. tained on diets of purified nutrients. Problems of metabolism of protein Patiently and persistently, the work and its requirement are still being went forward, until by 1955 Dr. Rose investigated. presented data for the recommended Attention also has centered on world daily intake of each of the amino acids problems of nutrition—especially on essential for people. the nutritional disease, kwashiorkor. Investigators in many laboratories The first description of this disease of have been at work since 1930 on the young children was given in 1933, and protein problem, including the nutri- attempts to identify the cause have tive value of individual proteins and gone on ever since. Kwashiorkor is the specific function of individual prevalent in the Tropics and in many amino acids. poor countries where carbohydrate Protein has been found to be the foods form the bulk of the diet and material for building muscle and body protein-rich foods are unavailable or tissue, and to be part of the hemo- too costly. "Protein malnutrition" globin molecule in red blood cells. often is used as the term for kwash- Enzymes and hormones have been iorkor, but present knowledge indi- crystallized and found to be derived cates that they are not synonymous. from proteins. Enzyme systems contain Kwashiorkor may be due to a de- protein. Antibodies present in the ficiency in the kind and the amount blood stream, an aid in resistance to of protein or of many of the other infection, are protein in nature. essential nutrients. The advances since We usually discuss pellagra along 1900 in our knowledge of proteins and with the vitamins. A "pellagra-preven- amino acids have centered attention on tive vitamin" was sought in the early people the world over who do not get 1920's. The search continued until enough protein. We also know we need 1937, when Conrad Elvehjem, of the to study the vegetable proteins further. University of Wisconsin, fed nicotinic acid (which had been on the chemists' FATS AND OILS have been foods since shelves for a long time) to dogs with ancient times, but not until 1814 did blacktongue, a disease comparable to a chemist, Michel Eugene Ghevreul of pellagra in humans. Nicotinic acid France, discover that fats are made of cured the blacktongue, and soon was fatty acid and glycerol. He also named found to be effective in treating human margarine. pellagra. Nicotinic acid was added to A century ago heated arguments the list of known vitamins. Its name went on over whether the animal body was changed to niacin to avoid could change carbohydrates into fat. confusion in the mind of the public. Experiment was the only way to find But the story of the fight against an answer. Fat-free diets were fed to pellagra belongs with the proteins. pigs, ducks, and geese. Analysis of the Investigations were carried on by carcasses later disclosed the presence Joseph Goldberger throughout the of fat in the body; it could have arisen South, where pellagra was serious only from the carbohydrate of the diet. from early 1900's till the late 1930's. The use of the calorimeter demon- He found that certain protein-rich strated that fats have two and one- foods prevented or cured pella,gra. The fourth times the caloric value of carbo- complexities of this relationship were hydrate and protein. By the beginning difficult to unravel and illustrate the of the 20th century, it was accepted interrelationship between nutrients. that fats and carbohydrates could be The answer was found not long ago: used interchangeably in the diet. It The amino acid tryptophan can be was thought therefore that fats were THE SrORT OF NUTRITION 17 not essential in the diet. Fats were University under Dr. Atwater and consumed in large amounts because of later at Columbia University. These their flavor and satiety value, but elements were recognized as essential comparatively little nutritive impor- in the diet, and many experiments tance was attached to them, except for were conducted to try to determine their energy value. Then in 1915 came just how much of each was needed, the startling discovery that certain fats, •exactly how they functioned in the such as butter, were sources of the body, and how they were afí'ected by newly discovered vitamin. Soon other food preparation. Some of these ques- fat-soluble vitamins were discovered. tions are not yet satisfactorily answered. New interest was aroused in 1929 Doubt existed for a time as to the when scientists observed that rats kept form of these mineral elements, but on a fat-free but otherwise adequate belief in the special virtues of organic diet (with vitamins supplied in other combinations, especially of phospho- preparations) did not maintain health. rus and iron, gradually gave way to The animals lost hair from the body the recognition that inorganic combi- and developed a skin disease and nations were equally well utilized. necrosis of the tail. This condition By 1930, as newer techniques and ap- could be prevented by feeding fatty paratus made it possible for chemists acids that were highly unsa tura ted in to measure minute amounts of certain structure. Linoleic acid was identified inorganic substances, the significance as the essential fatty acid. Linolenic of the trace elements in nutrition was and arachidonic acids serve the same recognized. function. This new knowledge made Iodine had been identified a cen- it possible for researchers to prepare tury earlier. In the 1920's it was iden- experimental diets, which led to the tified as an essential nutrient. The discovery of more of the vitamins. thyroid gland at the base of the neck Once again, interest centered on the enlarges when it is deprived of iodine. vitamins in nutrition. The condition is known as simple The high content of fatty substances goiter. In the Great Lakes area, where in the thickened artery walls that is iodine has been leached out of the often associated with heart ailments has soil and so is not available in food or again aroused interest in the possible drinking water, goiter used to be a relation of dietary fat to those condi- common occurrence among children, tions. Much work is being done on especially girls. fats, the amount and chemical nature One of the earliest large-scale con- of the fats, and the fatty acids that trolled human experiments was con- should form part of inan's daily diet. ducted by David Marine and O. P. Perhaps there is yet to be found a Kimball in 1921 with 6 thousand pattern of the kind and amount of schoolchildren in Akron, Ohio. They fatty acids needed in the diet, as was showed that children given iodine in done for amino acids. drinking water did not develop goiter; a large proportion of those not so INORGANIC ELEMENTS—or mineral treated did develop this condition. constituents, ash, or inorganic salts, as A more efí'ective way of providing a they have been called—were known a readily available and safe supply of century ago to be essential for plant- iodine for all people was developed life. Farm animals did not thrive if later by adding potassium iodide to common salt was omitted from their table salt. Use of this salt has always diet. been on a voluntary basis, but it At the beginning of this century, provides a wise public health measure Henry G. Sherman began studies on available to all people. calcium, phosphorus, sulfur, and iron Investigators in the University of in human nutrition, first at Wesleyan Wisconsin in 1928 found that pure 477248'=—59 3 [8 TEÁRBOOK OF AGRICULTURE 1959 iron salts were ineffective in curing ane- termine where the heavy hydrogen mia in rats and that small amounts of was deposited. He found that the fatty copper had to be present in the diet acids of the stored fats are constantly before the iron could be utilized. transported to and from organs. They Manganese, magnesium, and zinc merge indistinguishably with the fat were next added to the list of elements from the diet and are converted into that are needed to maintain growth* other fatty acids of both longer and and health in experimental rats. shorter chains. Only the essential un- Cobalt was found necessary to pre- saturated fatty acids did not take up vent disease in cattle and sheep (1935). heavy hydrogen—thus further con- With the discovery of vitamin B12 firming the earlier finding that the un- (1948) and the later chemical identi- saturated fatty acids cannot be synthe- fication of cobalt as one of its con- sized in the body but must be supplied stituents, this element has joined the in food. Ust of those which are known to be Another series of experiments was essential for people. made in a similar way. Heavy nitrogen These are the major nutrients that was used as part of the amino acids fed have been identified so far. to mice. As with fats, there was a rapid The story of nutrition is more than interchange between dietary amino one of discoveries of new compounds acids and those of the blood and tis- needed by the body, however. sues. The amino acid lysine was the The problems of nutrition continue only one that did not take up heavy to grow more complex. New discov- nitrogen from the "labeled" amino eries reveal that there is close inter- acids. Dr. Schoenheimer demonstrated relationship between many of the that the body constituents were in a nutrients. Numerous factors affect the dynamic state. Another new concept availability of the different nutrients of nutrition was introduced. as they exist in food. The biochemical Radioactive isotopes of other ele- individuality of each person must be ments—calcium, phosphorus, iron— kept in focus in providing for man's are now available, valuable tools for nutritional needs. following the pathway of nutrients Food nutrients arc converted into within the body. body structure. For a long time it was thought that the body material, DIETARY STUDIES on man have been especially the fat deposits, was more carried out through the ages, and I or less stable. mention some examples to show prog- How could one tell? It was possible ress by this avenue of study. Most of to analyze and know exactly what the nutrition studies have been made was taken in by mouth and what on experimental animals. One cannot was excreted, but what happened deliberately deprive man of essential inside the body was pretty much foods, but history and geographical unknown. and economic circumstances have This was so until the early 1930's provided opportunities for the experi- brought the discovery of heavy hy- mental study of man. drogen and heavy nitrogen by Harold Sanctorius in the 17th century C. Urey, an Indiana boy who became sought an explanation of metabolism a professor in Columbia University as he weighed himself and his food. and in 1934 won the Nobel Prize for The outcome was a book of apho- chemistry. risms—a happier ending than the one His discovery was put to work by a young physician, William Stark, had biochemist Rudolf Schoenheimer, who in the 18th century. He was a healthy incorporated heavy hydrogen into young man of 29, with a desire to find fatty acids and fed them to mice. By the effect of diet on health. He ate sacrificing the animals, he could de- carefully weighed amounts of bread THE STÖRT OF NUTRTTION 19 and water, and added various other Another study was that of Lord foods one at a time. He fell ill in a few John Boyd-Orr and his coworkers in months and died from what in the 1931 of the health of two African light of today's knowledge was prob- tribes living in the same area but with ably severe vitamin deficiencies. diñ*erent food customs. James Lind was more fortunate. His Physical and medical examinations, classic experiment was the first clini- blood analyses, and careful examina- cally controlled one and showed that tion of food intakes were made on sev- lemon juice cured scurvy. eral thousand tribesmen. The Masai Toward the end of the i gth century, tribe was a pastoral group that lived Max Rubner in Germany, Lyon mainly on milk, meat, and raw Playfair in England, and Wilbur O. blood—a diet relatively high in pro- Atwater in the United States made tein, fat, and calcium. The Akikiyu many studies of diets. They reasoned were agricuUurists living on cereals, that groups that were vigorous and roots, and fruit—a diet relatively high healthy surely had adequate diets. By in carbohydrate and low in calcium. analysis of diets of these groups, they The Akikiyu had a higher incidence believed they could find what was an of bone deformities, dental caries, adequate intake of calories and protein. anemia, pulmonary conditions, and Atwater recommended 3,400 Calo- tropical ulcer. The full-grown Masai ries and 125 grams of protein for a man males averaged 5 inches taller and 23 who does moderately active muscular pounds heavier and had greater mus- work. He considered fat and carbohy- cular strength than their neighbors. drate to be interchangeable as a source Once again, the evidence suggests of calories. that laboratory findings about nutri- The newer knowledge of nutrition tive value of foods are borne out by was well established by 1926, and ade- direct studies of human beings. quate human diets could readily be Further emphasis of the importance obtained from natural foods. of nutrition was given by the studies The inquiring mind of Dr. H. C. of Dr. Frederick Tisdall and cowork- Corry Mann, an English physician ers in Toronto, who in 1941 found that who was in charge of a boys' home, the physical condition of infants at led him to wonder if he could improve birth was markedly superior when the what was considered by all standards mothers had received an adequate of the. day to be an adequate diet. diet during pregnancy. One group of his boys remained on the The findings were verified in 1943 regular diet. Six other groups received, by Dr. Harold Stuart and Mrs. Bertha respectively, additions of sugar, butter, Burke in Boston. They took records of margarine, casein, w^atercress, and 216 pregnant women whose diets milk. All the groups that got the extra could be classed as good, fair, poor, items increased more in weight and and very poor. The health of each height at the end of a year than the baby reflected the quality of the group on the regular diet. The group mother's diet. Most of the infants born that got milk made far greater gains. to mothers who had good or excellent Later discoveries of vitamins and diets during pregnancy were in good further knowledge of nutrients have or excellent physical condition at contributed some of the answers re- birth. Infants born to mothers on poor garding the value of milk as a food. diets were mostly in fair or poor physi- This study again demonstrated the cal condition, stillborn, or prematurely value of the concept introduced early born. The poor diet during pregnancy in the century by Dr. McCollum that did not appear to afí^ect the mother's biological investigation provides infor- health, but it did afi'ect the health of mation that cannot be obtained by the infant. The amount of protein in chemical analvses. the mother's diet also was correlated 20 TEARBOOK OF AGRICULTURE 1959 with the weight and length of the and calcium from the added milk infant at birth. powder in diet B definitely contributed to the improved growth and longevity SCIENTISTS have wondered for a long of these animals. time whether nutrition affects the The depression years provided clini- length of a person's life. cal material for the study of nutritional Luigi Cornaro, a Venetian of the deficiencies in man. They also aroused 16th century, was overindulgent in his nationwide concern that our people be youth, but after the age of 40 he kept adequately fed. to a strict dietary regimen. The results What is an adequate diet is hard to were fine for Cornaro; he lived to be say. Lord Boyd-Orr has defined health 100. In his old age he wrote enthusias- as a "state of well-being such that no tically of the joy of living. improvement can be effected by a Science demands better evidence change in diet." But what kind of a than that, however. diet will maintain such a state of It is difficult, if not impossible, to health? study longevity in relation to diet of Hazel K. Stiebeling, now Director of man under controlled experimental the Institute of Home Economics in conditions; no one investigator lives the Department of Agriculture, was long enough to complete such a study. one of the scientists who considered But if results from experimental rats the problem of the hungry 1930's and can be appUed to man (and there is set up a working pattern of amounts of evidence that such findings are in nutrients and food required daily for many cases applicable), then Henry individuals of diff'erent ages, sex, and G. Sherman's experiments at Colum- activities. Dr. Stiebeling guided a bia University have provided an nationwide study of food consumption answer. of a representative sampling of the Beginning in 1920, Dr. Sherman population of the United States in the started two series of rats on diff'erent mid-l93o's. The diets were evaluated diets. Diet A, of dried whole milk and in terms of adequacy as compared ground whole wheat, was adequate with the standard of requirements. for growth and reproduction. Diet B The publication, "Are We Well Fed? had a higher proportion of milk A Report on the Diet of Families in the powder, and so was better. Succeeding United States," aroused widespread generations from the original animals concern and led President Franklin D. were maintained on the same two Roosevelt to call the National Nutri- diets. By 1949, the 70th generations tion Conference for Defense in May were still thriving. This is somewhat 1941. At the same time the National like taking two families before the Academy of Sciences-National Re- time of Julius Caesar and studying search Council appointed a Committee their descendants continuously up to on Food and Nutrition to develop a the present time. table of "Recommended Daily Allow- Diet A was adequate for growth and ances for Specific Nutrients." reproduction through all the genera- War problems provided a further tions of rats. On diet B, the better stimulus to the study of nutritional diet, the animals showed differences needs of all people. Representatives of which were statistically significant: 44 nations met at Hot Springs, Va., in A more rapid and efficient growth, 1943 to consider ways and means by earlier maturity, longer duration of which each country might increase the reproductive life, greater success in food resources and improve the diets rearing of young, and increased length of their people. From this conference of life. came the meeting in 1945 in Quebec Other studies by Dr. Sherman when the Food and Agriculture Or- showed that the increased vitamin A ganization of the United Nations was THE STÖRT OF NUTRITION established. It has done much through fication of milk v/ith vitamin D was the years to study malnutrition, deter- begun in the early 1930's. The Council mine nutritional needs, and promote on Foods and Nutrition of the Ameri- food production and improvement of can Medical Association approved the diets of people all over the world. fortification of milk with 400 Inter- Enrichment and fortification of food national Units of the vitamin per was another milestone in nutrition quart. progress. Enrichment was made pos- Considerable evidence had accumu- sible in the 1940's by the chemists' lated by 1941 that many American ability to prepare pure nutrients in in- families were consuming diets that expensive forms and was made neces- were inadequate in thiamine, ribofla- sary by the findings that the average vin, niacin, and iron. Because we also American diet of that period was in- were concerned with the problems of adequate. w^ar in Europe, the National Nutrition I have mentioned the incidence of Conference for Defense was called in goiter and its prevention by the addi- May of that year. The Government tion of small amounts of iodine. Po- was studying proposals to add some tassium iodide was added to table salt vitamins to flour and bread. A Com- and made available to the public on mittee on Food and Nutrition (later the grocery-store shelves in 1924 and called the Food and Nutrition Board) the benefits of this public health meas- had been established in 1940 to pro- ure have been demonstrated. vide direction for the national nutri- Vitamin A has been added to mar- tion program. The committee pro- garine to make it a good source of posed the use of the term "enriched" vitamin A. Such fortification is manda- and set up minimum and maximum tory in some States, and margarine limits for the enrichment of bread and with 15 thousand International Units flour with thiamine, riboflavin, niacin, of vitamin A per pound is available in and iron. With the support of the m.ill- most parts of the country. ers, enriched flour became available The Danes first realized the need for to the public and was used by the adding vitamin A in this way. During Army and Navy. Riboflavin, how- the First World War, practically all ever, w^as not available in adequate the butter of Denmark was exported. amounts to use until the end of 1943. Subsequently an eye ailment was ob- The bread-and-flour-enrichment pro- served in young children and was gram has been a controversial one. recognized as a vitamin A deficiency. Some have maintained that the public As a preventive measure, vitamin A should be educated to the use of natu- concentrates were added to margarine. ral foods that would supply all nutri- Other countries adopted the practice. ents, but experience of centuries has. The Council on Foods and Nutrition shown that people are reluctant to of the American Medical Association change their food habits and that edu- approved it in 1939, and it has since cation regarding food choices is a slow been advocated by the Food and Nu- process. More than half the States re- trition Board. quire the enrichment of flour and The discovery of vitamin D as the bread. South Carolina was the first to antirachitic vitamin and the recogni- do so. tion of fish-liver oils as a potent source Dietary studies give evidence of the led to the advice that babies should re- nutritional improvement of the food ceive cod-liver oil or some concentrate intake of various groups and clinicians of vitamin D. Prevention of rickets and have reported declines in nutritional development of strong bones in young deficiency symptoms. But there have children depend on an adequate in- been improvements in family income take of calcium and phosphorus, as and family food expenditures since . well as vitamin D, and therefore forti- the enrichment program began and YEARBOOK OF AGRICULTURE 1959 these are contributing factors. Never- The Food and Nutrition Board of theless, all experimental evidence to the National Academy of Sciences- date shows that nutritional improve- National Research Council (1940) has ment of diets brings improvement in guided the application of the science health. Especially is this so when the of nutrition through its recommended article of food is a staple. dietary allowances. The members of the Board also prepare bulletins FROM THE MINDS of men haVe come summarizing and interpreting current the ideas and from the laboratories research in nutrition. have come the proof (and sometimes Nutrition research workers in the disproof) of the ideas on which our laboratory have been greatly aided by knowledge of nutrition is based. Nu- grants from the Williams-Waterman trition laboratories are expensive to Fund (1940). This fund was named maintain. for Robert R. Williams, "the father of Therefore the story of progress would enrichment," who devoted 26 years to not be complete without reference to the search for thiamine. Robert E. some of the organizations and agencies Waterman was Williams' partner in that have contributed funds for sup- the last 12 years of his search. Together port of research in nutrition and have they found the way to make thiamine provided opportunities to know the so cheaply that it can be used for work of others through professional enriching bread, flour, cornmeal, and meetings and publications. rice. Our account of how the study of Another important source of finan- nutrition emerged as a science began cial aid to the research works in with Wilbur O. Atwater and his nutrition is the Nutrition Foundation research in the Office of Experiment (1941). Food manufacturers through- Stations. Experiment stations in every out the country support the founda- State now carry on the search for tion, and Dr. Charles G. King, who knowledge. Other divisions of the isolated pure vitamin C in 1932, in Department of Agriculture are en- 1942 became director of its program gaged in a wide variety of basic and of aid for research and dissemination applied problems related to nutrition. of information about nutrition. Chief among them is the Institute of Alone and in teams, in private Home Economics, which was estab- laboratories and the State experiment lished in 1923 as the Bureau of Home stations, and in colleges, universities, Economics. clinics, medical schools, and industrial The United States Public Health firms, men and women in this and Service also has made an outstanding many other countries have sought the contribution. The story of the fight answers to the intricate problems of against pellagra and the use of iodine man's health and well-being as in- to prevent endemic goiter have been fluenced by his food. Great progress told. Men of the Public Health Service has been made. Much remains to be were in the forefront. learned, however, and that is the Three professional organizations challenge we have now. have among their members many men and women who were the students ELIZABETH NEIGE TODHUNTER is the of Mendel, McGoUum, and Sherman Dean of the School of Home Economics^ and who have carried on research and University of Alabama, and a past presi- teaching in all phases of nutrition. dent ^ ^957-1958, of the American Dietetic These organizations are the American Association. She has done extensive research Home Economics Association (igog), in nutrition and written widely on the his- the American Dietetic Association tory of nutrition. She is a graduate of the (igi7), and the American Institute of University of New Zealand and of Colum- Nutrition (1933). bia University, New Tork,