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The metabolic process by which an apple, a tomato or a portion of cabbage is made into hair, or muscle or nerve, or some of the cells of the eyes, or into a hormone of some of the ductless glands is beyond our present comprehension, although a few steps in this process are supposed to be known. What we do know is that if the foods we eat are to be made into tissues and secretions, they must contain adequate amounts and due proportions of all the elements needed in the production of these things. Just as we cannot make concrete with cement alone or with sand alone, but must, if our concrete is to be good, have due proportions of both, so, if we are to have good structures in our bodies, we must have adequate amounts and proper proportions of all the food elements that go into the construction of these structures.
To make the best use of any food element, such, for example, as the proteins, certain other food substances and possibly a variety of them must be available in the diet in definite proportions. No food element is of itself of more importance in the body than another. It is only by the combination of all the necessary ones that the whole may be obtained.
Liebig laid down a "law of the minimum" in these words: "The development of living beings is regulated by the supply of whichever element is least bountifully provided."
The law of the minimum implies that the nutritive value of any food-mixture, however abundant most of the food elements therein may be, is limited by the minimum quantity of any essential element it may contain; unless, as it happens in certain food constituents, the lacking factor may be synthesized from some of the more abundant food elements, fat from sugar, for example.
Calcium cannot be utilized in producing enamel in the absence of phosphorus. If phosphorus is present in inadequate amounts, the enamel will be of poor quality. If iron is lacking, there will also be poor enamel. If any one of the vitamins is lacking poor enamel is the result.
The united "action" of minerals, proteins, vitamins, etc., in the production of tissues and fluids in the body is called "synergistic action." Since they do not act, but are used, it may be more correct to say that the body makes correlated use of them. At any rate, a knowledge of the "synergistic action" of the food elements and vitamins is of vast importance and helps to make clear to us the Law of the Minimum.
Tooth enamel is made up largely of calcium and phosphorus with small quantities of iron. But the fusion of these substances into enamel requires the presence of vitamines A, C and D. At least half a dozen elements and factors are essential to the production of this tissue. In the absence of either of these factors the enamel of the teeth cannot be made. It is folly to feed much calcium in an effort to produce good teeth and to ignore the other essential elements of the teeth.
Many different tissues are being built and repaired in the body at all times. These tissues are constantly engaged in a wide variety of activities. This means that there is a continuous use of vitamins, minerals, amino acids, sugars and fatty acids in the body. Consuming an abundance of a single vitamin or of a single mineral is not sufficient to meet the needs of the many "synergistic actions" that are in constant process in the body. All of the vitamins and all of the minerals are required. If all the nutritive elements are present in adequate quantities and in due proportions, all the synergisms of all the minerals, vitamins, amino acids, sugars, etc., are at work piling up their benefits.
It is well to keep in mind that these "synergistic actions" are far more complex and broader than our description of them would indicate. The many functions of the body are also synergistic. The function of one part of the body is dependent upon the functions of all other parts. Feeding vitamin B in certain forms of nervous trouble with the aim of remedying the nervous impairment, and ignoring the correlated functions of the body that support nerve function, is doomed to failure. All of the "synergistic chemical actions" in all parts of the body must be adequately provided for before the actions of any part can be ideal. This is the thing that makes specific diets so unsatisfactory.
The work of potassium in promoting the formation of proteins, fats and glycogen, is not essentially unlike the work ascribed to vitamins. Zinc is thought to be connected with the action of the vitamins, which it seems to be able to replace to some extent, at least in the animal organism. Lithium is also thought to influence metabolism in a way not unlike that of the vitamins. The same is true of copper, nickel and of arsenic. It should be borne in mind that little is known about the offices of zinc, lithium, copper, nickel and arsenic in the body and that experimenters, carrying out their experiments, have wholly neglected these elements.
In plant life and growth the Law of the Minimum has long been known. If perfect growth is to be procured in plants, these must find a certain minimum of each of several elements in the soil in which they are grown. If only half the needed amount of potassium, for example, is present, then, regardless of how abundant all the other soil elements may be, their normal utilization is reduced one-half. The rate of growth of the plant and its ultimate development are correspondingly depressed.
Prof. Osterhout showed that seeds placed in distilled water grow better than when placed in water containing but one salt, and that each salt exerts a specific toxic effect according to its chemical nature. He found that one salt "counteracts" the effects of another.
An excess of nitrogen in the soil retards the formation of grain, roots and tubers and gives rise to sickly plants. Nitrogen excess in the soil of rose beds leads to the production of soft, sappy tissues, a luxuriant growth of leaves, and roses with little or no perfume.
Plant processes, from germination to ripening of their seed, are a drama of physiological minerals and gases. Without a sufficiency of lime or potash in the soil, acids, sugars and starches cannot be formed; without iron no chlorophyll and no albumen can be formed. Without silica no fibre or plant skeleton, etc. Each mineral plays a definite role in the growth of healthy plants.
The actual amount of potassium requisite for plant growth is very small compared with the needed amount of carbon or nitrogen. But if this relatively small quantity is not available the utilization of other constituents in tissue growth or repair is always deficient.
If one essential food element, which normally should compose one per cent of the food eaten, is present in only half this amount, then, the body will only be able to utilize the other elements, in tissue building, in the same reduced quantity.
The organic whole--the unit--is official to animal nutrition. Not the sum total of the minerals consumed, but their relative proportions, determines the nutritive value of any given dietary.
A certain minimum amount of organic salts is essential to optimal growth. A further increase in these, even a great increase, does not further influence growth. Not only the total quantity of these salts, but also the quantities of the individual minerals and their mutual quantitative relationships are of decisive importance in regulating the assimilation of proteins.
If we are to have normal development the mineral elements in our diet must also be present in minimum quantities, but they must also represent proper ratios one to another. The mineral salts are most sensitive to any deficiency of any of them in the diet. Many common foodstuffs are deficient in iron and calcium, and these deficiencies reduce the ability of the body to assimilate the other elements. On the other hand, in experimental diets, any increase of one element raises the mineral requirements of all the others.
If health and development are to follow, certain relationships must prevail between the various salts. Berg, McCarrison, McCollum and others have amply demonstrated this. Rose found that a certain relationship must prevail between calcium and magnesium if the maximum development of the body is to be attained. Between lime and potassium, lime and sodium, potassium and magnesium and between the metals on the one hand and sulphur and phosphorus on the other, an optimum ratio exists.
The proper exploitation of both proteins and carbohydrates is determined by mineral metabolism, since they can be more readily oxidized in an alkaline medium than when an excess of acids is present. It has been repeatedly shown that an excess of bases over acid-forming foodstuffs ingested promotes the utilization of proteins. Zunts, of Berlin, showed that diabetics can more easily oxidize sugar if the body has an abundance of bases at its disposal. Abderhalden performed investigations which showed that a diet rich in bases is essential for the proper functioning of the hormones of the ductless glands.
Without iron there can be no oxygen supply for the cells. Without copper there can be no assimilation of iron. Without sodium there is no elimination of carbon-dioxide from the tissues of the body. Every physico-chemical process of the body is correlated with others and any failure in one spells a corresponding failure in the correlated processes.
May Mellanby says that the evidence shows that the calcium in the diet does not in itself directly control the calcification of the teeth, but that it is subservient to other dietetic factors. One of these is vitamin A. She thinks that she has demonstrated the existence of factors in some foods, particularly in cereals, and more especially in oats, that inhibit calcification. Phosphorus is as essential to the formation of good bones and teeth as is lime.
The present furore over vitamins has caused many ex-spurts to concentrate their whole attention upon these substances and almost forget the other elements of nutrition. We pick up a book or a magazine article or a report dealing with nutritional problems and we learn that a diet rich in vitamin A does thus and so, or a diet poor in vitamin B results in such and such effects. The minerals in the diets are particularly overlooked. Interest in vitamins is causing us to forget the importance of other food elements.
The present over-emphasis on vitamins is as absurd as if we were similarly to over-emphasize sodium, or magnesium. To ignore the organic salts, as is so often done in our mad rush for vitamins, is as foolish as would be the ignoring of the vitamins.
It has been demonstrated that regardless of the amount of vitamin A supplied in the diet, if some other constituent of the diet is wholly lacking, vitamin A can have no effect. Berg shows that on a cereal diet complete in A is without effect unless sodium and calcium are added to the diet in sufficient quantities to produce an excess of bases. McCollum and his co-workers have shown that when there is an abundance of vitamin A in the diet, the mother cannot secrete sufficient milk for her progeny, unless her food contains an adequate amount of organic salts in proper proportions.
The absence of anyone of the essential vitamins prevents the rest of them from functioning at all. If any one of them is present in but one-half or in but one-fourth the required amount, then the others, though abundantly present, will function only up to one-half or one-fourth of their full effectiveness.
Lack of vitamins disturbs calcium metabolism. A lack of calcium or an excess of calcium in the diet renders vitamin A of no effect. Vitamins are valuable only in the presence of each other. Calcium seems to be usable only in the presence of vitamin A.
McCarrison says that "in the absence of vitamins or in their inadequate supply, neither proteins, fats nor carbohydrates nor salts are properly utilized; some are largely wasted, while others yield products harmful to the organism. In such circumstances life may be sustained for a longer or shorter period, during which the body utilizes its stores of vitamins and sacrifices its less important tissues to this end. But there is a limit beyond which such stores cannot be drawn upon, and once this is reached the cells of higher function--secretory, endocrine and nerve cells--begin to lack vigor, and to depreciate in functional capacity, although the tissues may continue to hold considerable stores of vitamins. The disintegration process is delayed or hastened, lessened in severity in one direction or increased in severity in another, according to the character of their lack of balance."
There are many kinds of proteins and where one is securing his protein from one source only he is likely to suffer from protein inadequacy even though he is consuming an excessive amount of protein. The biological value of the various proteins varies considerably.
Proteins are broken down into their constituent ammo-acids in the process of digestion and these amino-acids are employed in constructing new and different proteins in the body, but amino-acids may be utilized by the body only to the extent that the diet supplies other protein constituents which enable the body to synthesize them into proteins proper to man. If more amino-acids are introduced into the blood than the presence of other elements will enable the body to utilize, the amino-acid content of the blood rises and there is an increased excretion of amino-acids in the urine.
It is at once apparent from this, that growth can proceed at an ideal rate only as rapidly as all of the essentials of growth become available to the growing organism.
It is found, in harmony with this law, that in the case of proteins, the value of a protein or mixture of proteins for structural purposes in the body, is limited if one of the indispensable amino-acids is deficient or wholly lacking. If and when this deficiency is remedied, a deficient supply of some other indispensable amino-acid constitutes a further limitation.
Attempts are often made to determine the value of an article of food by using as an index to its fitness, the amount of some element contained in it; let us say phosphorus. This effort is based on a misconception of the office of these elements in nutrition. To over-emphasize the importance of any of the salts--iron, calcium, potassium--or of any of the vitamins or complettins, or of protein or carbohydrate is to overlook the essential fact that these things function in nutrition only in union with the other elements.
This law of the minimum applies even to water. It has been shown repeatedly that if water is limited to a certain extent in the diet of infants, and all the other growth essentials are adequate, growth will not take place. Children placed on dehydrated diets can be taught within a very short time to take and be content with a small amount of water. The body establishes a water balance on a very low level but does not grow.
Many scientists have concentrated on single issues, seeking in these the secrets of life. But this concentration on one detail caused them to overlook the importance of the tout ensemble. Schaumann, for example, attempted to show that beriberi (polyneuritis) is due to the loss of a phosphorus compound in the milling of whole grains. Chamberlain checked up on his assumption and found it to be wrong. Several elements are lost in the milling of grains and the troubles resulting from consuming denatured grains grow out of the total deficiency.
The effort to supply us with isolated vitamins and minerals is essentially a medical rather than a tropholgic procedure and harks back to the antiquated notions that there are "specific diseases," having specific causes and requiring specific remedies.
Every tissue builder is dependent upon all the others. The decisive factor in development is not so much the absolute quantity of the various food elements in the diet, but their relative proportions. The organism's need for one element of food may be supplied only when all other elements are supplied in relative proportions. The diet must contain a sufficiency of all essential food elements, but there must be no great excess of any of these.
The amount of any given element available for utilization by the body depends, not alone upon the proportions of other elements present in the diet, but also upon other factors. The organic salts enter into important reciprocal relationships, especially in the work of secretion, but also in the process of synthesizing new organic compounds, so that we are concerned with both a qualitative and a quantitative minimum. If an element is being fed in quantities that are adequate per se, but some other and antagonistic substance is also being given, the quantity of the first is thereby rendered inadequate. An adequate amount of calcium, for example, would be rendered inadequate by the medical administration of acids, or by acid fermentation in the digestive tract. The calcium would be exhausted in neutralizing the acids and little or none would be left for the body. An abundance of calcium coupled with a lack of sodium means trouble, for the sodium is essential to keep the calcium in solution.
The availability of a food element depends, not alone upon the amount and form of this element present in the food, but also upon the quantities of other elements present. The quantity of available calcium, for example, does not depend wholly upon the absolute quantity of calcium in the diet, but upon the quantity of mineral bases generally present in one's food. A shortage of these bases involves a drain on the calcium for purposes of acid-neutralization, and consumes an amount of calcium which would otherwise be available for assimilation.
After the alkaline salts have been consumed in neutralizing the acids in the foods themselves, the residue of these are available for storage in the body as a reinforcement of its alkaline reserve. The availability of the alkaline elements is proportioned to their excess over the food acids. This is the reason that our diet should at all times be preponderantly alkaline. McCarrison showed that an excess of fat or of unsaturated oleic acid in the food may cause a relative deficiency of iodine and enlargement of the thyroid.
MacCollum, of Johns Hopkins, states in his Pathology that there seems to be some relation between the deposition of calcium and the available supply of iron. Iron is not assimilated in the absence of copper.
An excellent example of this matter, on the positive side, is the increased protein-calcium-phosphorus retention produced by the use of orange juice. The regular use of orange juice results in an increased retention of these elements out of all proportion to the amounts of these actually present in the juice itself.
It has been found that a diet with an acid-ash residue results in a greater excretion of minerals than one with an alkaline ash. Oranges give an alkaline ash. Indeed, the addition of oranges to a decidedly acid-ash diet of much cereal, meat, and few vegetables, gives such a marked alkaline result that it shifts the reaction of the urine from a decidedly acid reaction to a decidedly alkaline one. This means increased mineral retention and also increased nitrogen assimilation.
Drs. Miller and Newell, of Iowa State College, added an ounce and a half of orange juice daily for three months to the otherwise unchanged diet of fourteen underweight children and tabulated the results. The weight of these children increased 146 per cent of the expected gain, in contrast with only 46 per cent observed during the preceding three months.
Dr. Cheney, of California, fed a group of undernourished children an orange a day. To another group he gave no oranges. During two different periods of two months each, the children who received the oranges gained an average of 141 and 118 per cent above the expected increases. The other group, without oranges, gained only 28 and 18 per cent above the expected gain. During the non-orange juice periods, including the preliminary days, the children gained an average of .08 pounds a day; with the oranges they gained an average of .3 pounds a day--approximately four times as much as without the fruit.
Failure of growth may rightly be considered a deficiency disease although, on certain types of diets, both animals and man maintain good health and proportionate development, failing only to attain their normal sizes. Except for size they seem to be normal animals. This is explained by the law of the minimum given at the beginning of this chapter. Such diets contain all the needed food elements and growth is determined by the elements least bountifully supplied.
Unfortunate experiences such as famine, war, poverty, and the ignorance that causes many people to feed upon denatured diets, prove that the laws of nutrition and growth are the same in man as in the lower animals and plants. The wise will understand.
To secure the highest possible development from food, it must be adequate in every respect. All of the food nutrients must be present in sufficient quantities and in due proportions and in digestible and assimilable, that is, available, form. This adaptation in the food is relatively more important while the child is growing most rapidly, and less important as the birth period, is receded from. Suitable variety and proper blending of foods, therefore, cannot be ignored, if we desire the highest vigor and greatest development in our children. Happily, except in isolated places and among the most poverty-stricken classes, the diet of the child may be easily controlled. Knowledge of correct feeding is needed by mothers.
McCarrison noted that under about the same conditions of filth and squalor, the Sihks and Pathans were much larger than the Madrassis and other peoples of India. He found the Sihks and Pathans eating leafy vegetables, curds and cheese, and these are lacking in the general Indian diet.
He fed a group of rats on the Sihk and Pathan diet and another group on the general Indian diet. The first group grew to great size; the second group remained small. He fed other groups on the customary Japanese diet, Philipino diet, Javanese diet and the characteristic diet of the ill-nourished English working man. The results of these diets he checked with the results of the Sihk-Pathan diet. The results were the same. All groups, except those fed on the English diet, were small in size; while the latter group attained nearly the size of the group fed on the Sihk diet but had rough coats and a combative disposition.
Experiments with Japanese school children, covering several years, show that similar additions to the regular diet of Japanese children cause them to grow to be several inches taller and several pounds heavier than the average Japanese child.
A few years ago the New York Times carried the picture of three boys of the same age (eight years); one an average American boy, of average size for his age; the other two, European boys, whose growth had been stunted by inadequate food. Neither of the European boys reached to the horizontally outstreched arms of the American boy. The European boys were victims of the war that had deprived them of food. In accordance with the law of the minimum, the growth of these two boys was relative to the element least abundant in their diet.
McCollum has repeatedly demonstrated that if a litter of rats is divided into two groups of four each, and one group is fed distilled water and whole wheat only, and the other group exactly the same quantities of distilled water and whole wheat, plus the addition of turnip or beet leaves, each rat in the first group will only attain the size of a large mouse; whereas, those in the second group will attain nearly double the size of those in the first group. Except as to size both groups of rats are "normal" in all respects.
We cannot better sum up what has gone before than in the following words of McCarrison: "It is unwise to consider any of the essential ingredients of food, whether proteins, carbohydrates, fats, salts, water, or vitamins, as independent of the assistance derivable from their associates in the maintenance of digestive and nutritional harmony. No doubt some of these have special relations to others, as for instance that of iodine to fats, that of vitamin B to carbohydrates, that of vitamin A to lipoids, calcium and phosphorus holding substances, and that of vitamin C to inorganic salts. But whatever be their special relations to one another they are all links in the chain of essential substances requisite for the harmonious regulation of life's processes; if one link be broken, the harmony ceases or becomes discord."