Vitamin Knowledge Incomplete But Important
( Originally Published Early 1925 )
What may be called the Vitamin theory as applied to food is based on one of the great discoveries of this century and is as yet far from being completed. The starting point was the study by Takaki, Medical Inspector General of the Japanese Navy, of the prevalence of the disease beriberi in the Japanese fleet wherein he reached the conclusion that the disease was caused by protein starvation. He devised a new ration to meet the condition, which was first very successfully used in 1884.
Twenty-three years went by before an eminent Dutch physician (Eijkman) came along with the announcement (1907) that he had experimentally produced a disease of dietary origin (beriberi). Eijkman also made other additions to our knowledge including the fact that if rice polishings were added to the condemned Japanese diet it would prevent the disease of beriberi. (Polished rice had been used in the Japanese navy.)
At the present day it is a common fact of medical opinion that beriberi is caused by a dietary deficiency of certain accessory food substances that have been called vitamins (vi'-tam-en, formerly written vitamines).
As to the substance of Vitamin A and B (originally called by E. V. McCollum fat soluble A, and water soluble B) they have not as yet been isolated and their character established. We become aware of their presence in food by a process of elimination.
McCollum reasoned that all types of nutrients are contained in a seed such as the wheat kernel, except possibly the unknown one which had been demonstrated to be present in certain fats. It was believed that valuable data might be secured by enhancing the protein, the inorganic element and the fat factors separately in feeding experiments. Accordingly McCollum and Davis in experiments that consumed much time and developed many perplexities fed the wheat kernel in the following combinations to rats and obtained the results noted: (1) Wheat alone. Result, no growth, short life. (2) Wheat plus purified protein, same result. (3) Wheat plus a salt mixture * which gave it a mineral content similar to milk. Very little growth. (4) Wheat plus butter fat. No growth. (5) Wheat plus protein, plus the salt mixture; good growth for a time, few or no young, short life. (6) Wheat plus protein, plus butter fat; no growth, short life. (7) Wheat plus the salt mixture, plus butter fat. Fair growth for a time, few or no young, short life.
After all these failures, conducted with critical care, came the 8th and very important and final experiment: wheat, plus protein, plus the salt mixture, plus butter fat; result, good growth, normal number of young, good success in rearing young, life approximately the normal span.
McCollum and Davis thus reached the conclusion that the only element of mystery in the normal diet (No. 8) was the unidentified substance in butter fat. From these experiments two new facts in nutrition emerged:
(a) The inorganic content of the wheat kernel, al-though it furnishes all the necessary elements, does not contain enough of certain of these to meet the requirements of a young animal during the growing period.
(b) The wheat kernel is too poor in its content of the unidentified substance which butter fat contains to nourish satisfactorily an animal over a long period of time.
It was later a great surprise to McCollum and Davis to find that polished rice, even when supplemented with purified protein, butter fat and a salt mixture, failed to produce growth in young rats Not only did they fail to grow but in some cases developed a state of paralysis suggestive of polyneuritis (inflammation of nerves). But it was found that the addition of wheat embryo or milk sugar in as small a quantity as 2 per cent of the food mixture supplied the missing ingredient needed to induce growth. Starch was experimentally substituted for this milk sugar. This slight change made the difference between success and failure. No growth could be secured when the milk sugar was omitted.
The experimental feeding method described above was later applied to other important seeds and to Ieaves, tubers and roots, as well as foods of animal origin. It consisted in feeding to one group of animals a natural food as the sole source of nutriment, and to other groups the same food supplemented with additions of purified food-stuffs. The interpretation of the results was based on the number of food factors which had to be improved before growth could take place, and the number which when so improved made a better diet as revealed by improved fertility, success in rearing young, span of life and general well being.
As a result of their experiments McCollum and Davis in 1915 set out what they recognized as an adequate diet. This must contain, in addition to the long-recognized dietary factors, in the form of protein, carbohydrates and fats, certain inorganic salts and two as yet unidentified substances or groups of substances. One of these is the fat-soluble A (or vitamin A) because it is found associated with certain fats, being specially abundant in butter fat, egg yolk fats, cod liver oil and the fats of the glandular organs, such as the liver and kidneys, but is absent, or present in but traces, in fats or oils of vegetable origin. The second substance, water-soluble B (or vita-min B), is never associated with fats or oils but is widely distributed in natural foods and can be isolated in a concentrated but not pure form from natural foodstuffs by extraction with either water or dilute alcohol. This water or alcoholic extract always contains the substance that cures polyneuritis (beriberi).
To show the nutritional value of each vitamin, and that one is not the equivalent of another, but that food should be so selected that each may be consumed in proper quantity in the course of the meal, the vitamins will now be taken up in the order of their alphabetical names.
The characteristics of this vitamin are very little known. Numerous experiments have been carried on for the purpose of concentrating it from vegetables and grasses. The finding of McCollum, Simmonds and Steen-bock that fat-free skimmed milk still contains Vitamin A has been confirmed. When steam is passed through butter for 2% hours the vitamin was found by Osborne and Mendel to be unaffected. It has been found that in the destruction of vitamin A oxidation (combining with the oxygen of the air) not temperature plays the chief part. Butter has been found stable when steam was passed through it but not when the butter was heated in the absence of water. The stability in this case may be explained by the replacement of air by steam although even dry butter could be heated at 96° centigrade (about 203° Fahrenheit) for 15 hours without noting any loss of activity. Cod liver oil contains 250 times as much vita-min A as butter and 3 milligrams of this oil per day (less than 1/7th of a drop) is sufficient for rats. Vitamin A occurs only in small amounts in seeds but during the process of germination it appears in greater quantities. Green leaves, Funk says, have been found to contain this vitamin under the influence of sunlight. It has also been found that the inner white leaves of cabbage are free from vitamin A while the outer green leaves contain the substance.
Osborne and Mendel found that the dry matter of tomato or of green leaves, such as spinach, contains an even higher concentration of vitamin A than does butter fat. Cooper has reported the presence of vitamin A in orange peel; and Osborne and Mendel have demonstrated its presence in the peel-free juice of the orange. In general it seems that cod liver oil, milk in all forms, beef fat, cream, egg yolks, butter, spinach (in particular), green vegetables and alfalfa are the food sources richest in vitamin A.
Definite conclusions as to the destruction of the vitamins by cooking and preserving processes have not yet been reached. Under ordinary conditions the belief seems to be warranted that such losses are not likely to be large. Steenbock and Boutwell found no demonstrable loss of vitamin A, when chard (Swiss lettuce), carrots, sweet potatoes, squash or yellow maize were heated for three hours under 15 pounds steam pressure at 120° centigrade (248° Fahrenheit) . McCollum and Davis report a high vitamin A value in canned evaporated milk (1918) and the same has been found to be true of ripened cheese.
The list of deficiency diseases attributed by Funk and McCollum partly or wholly to the lack of this fat soluble A is limited so far to a form of eye disease in the lower animals largely confined to the conjunctiva (membrane of eyes and lids) ; rickets (softening of the bones in small children) ; pellagra, surmised, not yet demonstrated (characterized by grave gastro-intestinal disturbances and skin eruptions, common in the South where there is a deficiency of milk) ; infantile scurvy, "recognizable"; sprue (a form of small mouth ulcers-thrush,) under suspicion.
The most formidible and interesting of these diseases from a popular standpoint is infantile scurvy. Of 356 cases of scurvy in infants reported to the American Pediatric Society (relating to children's diseases) in 1898, the following table is constructed, as to their diet:
Raw cow's milk, alone in 4 cases
Some experimental data leave no doubt that scurvy is a deficiency disease resulting from the lack of a specific chemical substance in the food. This substance is not essential to all mammals, but is indispensable to man, monkey and guinea pig (McCollum) and apparently also to swine and many other species (Plimmer).
On the subject of pellagra Voegtlin practically demonstrated at Spartansburg, S. C., in 1914, in over 100 patients in a pellagra hospital, who were not improving or gradually growing worse on a wrong diet, that prompt improvement would follow the addition of a diet rich in milk (increased 2500 per cent), fruit juices and proteins.
The old cases showed gradual improvement, ending in a large percentage of cures. Another group of new patients put on the corrected diet from the start showed definite' improvement within two weeks, while within two months all had recovered except a few far-advanced cases.
The health-promoting qualities of this vitamin have been much more clearly established than those of vitamin A. Absence of vitamin B causes loss of appetite, cessation of growth in the young and symptoms resembling those of beriberi. It may also include the bias (life) which stimulates the growth of yeast. Birds fed on polished rice, or the corresponding products of other grains, develop multiple nerve inflammation due to the lack of vitamin B. In mammals (the highest class of animals, including man) this lack causes loss of appetite with derangement of the organs of digestion and assimilation, disordered endocrine (glandular) secretions and malnutrition of the nervous system. A partial deficiency in this vitamin leads to impaired growth and a general under-mining of health and vigor. This lowered vitality may have a far-reaching effect in its influence on reproduction and successful rearing of the young. While the rationale (reason) of the physiological action of vitamin B is obscure and often referred to as growth-promoting (which is one of its qualities) it should be emphasized that this vitamin is essential to normal nutrition at all ages'
The principal food sources of Vitamin B are egg yolks, the whole grains of the cereals, entire wheat flour, beans, peas and seeds in general when eaten whole, rutabagas (Swedish turnip), beet leaves or stems (50 per cent richer than beet roots), raw, canned or dried tomatoes, cabbage (fresh raw), wheat middlings, yeast and yeast extract. It also occurs in moderate percentages but still in good sup-ply in barley, white and yellow cornmeal, oats, rice (not polished, containing the outside layer), rye, bran, fish roe, liver, kidney, brains, grape fruit, lemon juice, orange juice, cabbage (boiled 25 minutes, young 20 minutes), cabbage (raw), carrots, cauliflower, dandelion greens, egg plant, dried lettuce, onions, parsnips, white potato, boiled 15 minutes, ditto 1 hour, ditto baked, turnips, Brazil nuts, cocoanut, filberts, hickory nuts, peanuts, walnuts, milk, dried milk (whole), buttermilk, cream. The reader will remember the important opinion expressed elsewhere by McCollum that the two highly essential foods are em-braced in a quart or more of whole milk a day for an adult and plenty of the leafy vegetables, particularly spinach. He calls these two the "protective foods."
Vitamin B is relatively stable to oxidation and heat. The results of experiments by Chick and Hume suggest that little heat destruction will occur in ordinary cooking during which, if loss occurs, it is more likely to be on account of the solubility to water and loss by extraction if the cooking water is not used than through in-stability to heat at cooking temperatures. Vitamin B is the most stable of the vitamins
The effect of heat on vitamins is not yet a settled question but the most authoritative information is that it is immaterial under ordinary cooking conditions. A contrary view has been exploited by non-scientific commercial producers of so-called vitamin extracts, although this lately-discovered food accessory has never yet been identified, let alone extracted. There are plenty of vitamins for all in ordinary food. A typical instance of misrepresentation on this point is the widely-printed statement that vitamin A is destroyed at 100°. The fact is that H. Steenbock of the laboratory of Agri-cultural Chemistry, University of Wisconsin, states that the butter fat vitamin was completely destroyed at 1000.2 This 100° means 100° Centigrade (212° F.), or the boiling point of water. But the butter fat was manipulated by being shaken in water and the water separated from the fat in a vacuum. The fat was then found inactive. Butter fat through which air had been passed at the same temperature was also found inactive. But elsewhere in this book the fact has been distinctly set out that where air is allowed to pass through a cooking substance the vitamin content may be greatly reduced by uniting with oxygen of the air (oxidation). Osborne and Mendel say that butter fat through which live steam was passed for 2 1/2 hours did not lose its growth-promoting properties. But heated by Steenbock in jars at 100° Centigrade in the dry air of a Freas oven the butter lost its activity. The explanation of these apparently conflicting statements was set forth separately but simultaneously by Hopkin's of Cambridge University Laboratory (England) and by Drummond and Coward of the Institute of Physiology, University College, London, in the same Journal, and same issue.
The conclusive result can now be stated to be that the effect of a high temperature on vitamin A in butter is nil if the air is excluded by a lid. If the air is freely admitted at an exposure for 4 hours at a temperature of 120 C. (248 F.) it destroys the greater part of the vita-min vitality, and exposure to the same condition for 12 hours would seem to result in almost complete destruction?. Four samples of butter were maintained at a temperature of 37° C. (body heat) for three weeks. Two of these were exposed to the air and two protected from the air in stoppered bottles. The samples exposed to the air became bleached, that exposed to the Iight almost completely so, and both lost their power to restore growth to rats. The samples not exposed to the air remained unimpaired.
The heat-resistance power of butter fat is an academic question, as butter eaten for nutritional purposes is practically always eaten cold. The same can be said of milk, raw fruits, sliced tomatoes, salads, cream and nuts.
The effect of heat on milk is set forth by Anderson, Dutcher, Eckles and Wilbur of the Minnesota Experiment Station. It was found that milk heated to the boiling point was practically equal in nutritive properties and anti-scorbutic (scurvy) potency of unheated milk, provided it was kept in an undisturbed condition. Pasteurized milk heated to 145° F. for 30 minutes quickly lost its potency because it had been stirred rather violently wth motor-driven propellers, while the milk heated to the boiling point had not been stirred. It has now been demonstrated that under conditions of agitation a destructive influence is exercised on the milk vitamin by oxygen, one of the free elements of air.
Tomatoes, both raw and cooked, are an excellent source of vitamins both B and C and also of A in a slightly lesser degree. Hess and Unger 4 obtained good results with canned tomatoes in the prevention and treatment of experimental scurvy in guinea pigs. They also fed canned tomato to infants, substituting it for orange juice, and found that 15 cubic centimeters (tablespoonful is 16 c.c.) per day were well tolerated by infants over three months of age. They recommend this as an economical and efficient anti-scorbutic for children. Tomato, on account of its acidity, will stand heating at the boiling temperature without any loss to its vitamin B content, either fresh or canned. Its lesser vitamin con-tent is also immune to destruction at the same temperature if oxidization is prevented. Vitamin B in all its sources has so far been found resistant to cooking heat under the same conditions of non-exposure to air. This important vitamin is widely distributed and everybody can get plenty of it. But in cooking a number of authorities point out that the destruction of the vitamin content of any vegetable is facilitated by adding soda to the water, as some cooks do to make the vegetable greener.
The isolation of the anti-scorbutic (anti-scurvy) sub-stance presents greater difflculties than with the vitamins A and B. C is more easily destroyed by oxidation, heating, drying and other processes.
The action of heat on the anti-scorbutic value of vegetables and fruit juices has been carefully studied by Miss Pelf at the Lister Institute, London, with the following results:
Cabbage heated in water at 140° F. for 1 hour loses 70% of its value.
At 158-177° F. for 1 hour loses 99% of its value.
At 194° F. for 20 minutes loses 70% of its value.
Cabbage juice heated at 212° F. for 1 hour loses 99% of its value. Swede turnip juice heated at 212° F. for 1 hour loses 50% of its value.
Orange juice and lemon juice at boiling point for 1 hour. No apparent loss.
Like vegetables, milk suffers less loss of this element on boiling for a few minutes than by a gentle heating for longer periods. Hess has found that milk loses much of its anti-scorbutic value by excessive handling during transit from the cow to the baby. Many of the processes in the dairy involve the exposure of large surfaces of milk to the air and the frequent pouring of milk from one container into another'
Orange juice is an excellent anti-scorbutic and when boiled and rendered slightly alkaline is properly used in infantile scurvy as an intravenous injection (within veins), but in such cases the juice should be used immediately and not kept in the alkaline condition.
The same authors found that modified milk mixtures containing malt soup were especially prone to bring about scurvy in infants. This was traced to the practice of adding alkali (such as soda) to the malt soup where it exerted a deleterious effect on the anti-scorbutic vita-min of the milk.
Cooking cabbage at 230° F. for 1/2 hour did not entirely destroy its anti-scorbutic qualities. Berries after cooking retained their efficiency to a very large extent. Raspberry juice was not injured by heating to the boiling point for one hour. Injury from cooking was less when air was excluded. (Do not associate the above facts with vitamin B.)
Harden and Robison 3 say that apple juice concentrated to about 1/6 of its original volume forms a palatable jelly of distinct anti-scorbutic (scurvy) properties. The general use of fruit jellies prepared by this or a similar process is recommended as a substitute for ordinary jams or jellies, wherever there is reason to suspect that the diet is deficient in the anti-scorbutic vitamin C. If evaporated by the slow process of boiling there should be as little air movement as possible. Sugar can then be added. Open evaporation, instead of in the Kestner evaporator (as above) results in a considerable loss of vitamin vitality.
So far as fruits and vegetables are concerned the degree of ripeness at which the fresh fruit is most prized will probably approximate that at which it has the greatest vitamin value' Onions, stems of asparagus, celery, cabbage, lettuce, cress and spinach are all classed by numerous authorities as anti-scorbutic. Scalded milk loses about half its vitamin C value.
Kellogg says unfermented apple juice is exceedingly wholesome. It is a highly valuable remedy in gastric and intestinal catarrh, so-called biliousness, jaundice, constipation and in cases in which the kidneys and the liver are disordered; in emaciation, loss of appetite and general malnutrition. It may be taken up to a quart a day with advantage, preferably one-half hour before each meal. The proper way to preserve cider made from clean, selected apples is to heat to 165° F. for fifteen or twenty minutes. This will kill all fermentation germs. A higher temperature impairs the quality. The addition of benzoic acid as a preservative agent is highly objectionable. Bottled cider preserved by the above formula can be kept throughout the year and is as good as the natural cider, as the writer can attest.
As to the vitamin value of apples, raw, dried and cooked, Givens, McClugage and Van Horn of the Department of Physiology, University of Rochester, N. Y. report that 10 grams of raw apple or banana will protect a guinea pig against scurvy for three months. The use of these foods is advocated by Myers and Rose not only for healthy adults and infants but for the sick. The U. S. Department of Agriculture points out, how-ever, that there is a great difference between the digestibility of winter apples fresh from the trees and those that have had a month or two to ripen—a fact well known to experienced apple eaters. During this early period fall apples like Grimes' Golden should be eaten.
The deduction, therefore, seems warranted, although no express authority can as yet be found for it, that the juice of the apple as preserved by heat to 165° F. and kept corked has the same moderate vitamin A, B, and C, value as the raw apple, while such cider performs an important function as a part of the regular diet.
In his last work Funk observes that we must ask the question whether, with enumeration of the above three vitamins, we have exhausted all the possibilities. Hardly had Funk's book been published when Dr. E. V. McCollum of Johns Hopkins announced (June 18, 1922) the discovery of vitamin D, concerned with bone growth.
McCollum and associates destroyed the vitamin A by oxidation, and made cod liver oil incapable of preventing the eye disease, but without diminishing in a notice-able degree its value for the prevention or cure of rickets, and thus showed that certain fats contain two vitamins, one related to the functioning of the nutritional processes of the eyes, the other concerned primarily with the utilization of calcium and phosphorus in bones.
On the last day of December, 1923, before the American Association for the Advancement of Science, Prof. Lash Miller, of the University of Toronto, announced that in experimenting with an infusion of malt (wort) he had split off two new compounds which he had named Bios 1 and Bios 2. More than 50 vegetables and animal substances were studied and the bioses were found as widely distributed as vitamin B. Mush-rooms and white of egg contain more of Bios 2. The power of this compound in promoting growth is marvelous. If 1 part of bios is added to. 25,000 parts of a fermenting mixture the yeast plants grow ten times as fast as normal in a day.
March 19, 1924, Dr. Walter H. Eddy, of Columbia University, announced the isolation of Vitamin D. Four crystalline specimens of the isolated vitamin were exhibited to the audience. The composition was announced as 43 per cent carbon, 25 per cent nitrogen, and 8 per cent hydrogen, the remaining 24 per cent not then ac-counted for. (It will be noted that protein, a very complex organic substance, is composed of carbon, hydrogen, nitrogen and oxygen.)