The nutrition of man

by R. H. Chittenden

It is said that dietary studies made all over the civilized world “show that a moderately liberal quantity of protein is demanded by communities occupying leading positions in the world. . . . It certainly seems more than a remarkable coincidence that peoples varying so widely in regard to nationality, climatic and geographical conditions, and dietetic habits, should show such agreement in respect to consumption of protein and energy.” Again, we hear it said that “whatever may be true of a few individuals, with communities a generally low condition of mental and physical efficiency, thrift, and commercial success, is coincident with a low proportion of protein in the diet.” The writer, however, fails to find evidence in the results afforded by dietary studies that there is any causal relationship between the amount of proteid food consumed and the mental or physical supremacy of the people of a given nation or community. Cause and effect are liable to become reversed in arguments of this kind. It is certainly just as plausible to assume that increase in the consumption of proteid follows in the footsteps of commercial and other forms of prosperity, as to argue that prosperity or mental and physical development are the result of an increased intake of proteid food.

Proteid foods are usually costly, and the ability of a community to indulge freely in this form of dietetic luxury depends in large measure upon its commercial prosperity. The palate is an extremely sensitive organ, and the average individual properly derives great satisfaction from the pleasurable effects of tasty articles of food. Furthermore, there are many curious and quite unphysiological notions abroad regarding foods, which tend to incite persons to unnecessary excess and extravagance whenever they acquire the means to do so. The latter point is well illustrated by the more or less prevalent opinion that a cut of tenderloin steak is more nutritious than a cut of round steak. It is true that the former is apt to be more tender, to have a little finer flavor; but the round steak, when properly prepared, is just as nutritious, and equally capable of meeting the needs of the body, as the more expensive tenderloin. With increasing prosperity, we turn at once, as a rule, to the more tasty and appetizing viands, partly to satisfy the craving of appetite and palate, and partly because there is an inherent belief that these varied delicacies, accessible to the prosperous community, count as an aid to health and strength. The poor laborer, with his small wage, is restricted to a certain low level of dietary variety, and must likewise be economical as to quantity, but on the first opportunity afforded by a fuller purse he is apt to pass from corned beef to a fresh roast with its more appetizing flavor; to eschew brown bread in favor of the white loaf, and in many other ways to evince his desire for a dietary which, though perhaps no more nutritious, appeals because of its finer flavor, more appetizing appearance, and greater variety. He is in the same position as the smoker who, limited by his purse to a five-cent cigar after dinner, quickly passes to a cigar of better flavor as soon as his finances warrant the indulgence. At the same time, if prosperity continues, our laborer will speedily pass to a higher level of proteid intake and greater fuel value, through increased consumption of meat and butter, together with other articles rich in proteid and fat.

In this connection, we may emphasize a fact of some significance in its bearing on dietetic customs; viz., that ever since Liebig advanced his theory that proteid material is the sole source of muscular energy, there has been a deep-rooted belief that meat is the most efficient kind of food for keeping up the strength of the body, and hence especially demanded by all whose work is mainly physical. Although this view, as we have seen, has been thoroughly disproved, the idea is still more or less generally held that an abundance of meat is a necessary requisite for a good day’s work, a view which undoubtedly accounts in some measure for the tendency toward a high proteid intake, evinced by many of the laboring class whose means will permit the necessary outlay.

Increased consumption of proteid food may be coincident with thrift and commercial success, but there is no justification for the belief that these are the result of changed dietary conditions. The dietary of our New England forefathers was, according to all accounts, exceedingly limited as compared with that of to-day, but it is doubtful if the present generation is any better developed, physically or mentally, than the stalwart and vigorous people who opened up this country to civilization. To-day, as a nation, we have greater wealth, and our commercial prosperity has become phenomenal; but would any one think for a moment that these characteristics are attributable to the large consumption of proteid food so common to this generation of the American people? No, increased wealth simply paves the way for greater freedom in the choice of food; increased commercial success and business prosperity throw open avenues which formerly were closed; greater variety of animal foods, and vegetable foods as well, rich in proteid, are made easily accessible, and appeal to eye and palate on all sides; appetite and craving for food are abnormally stimulated, and dietetic habits and customs change accordingly. In the words of another, “the one thing that primitive, barbarous, and civilized man alike long for is an abundance of the ‘flesh-pots of Egypt.’ The very first use the latter makes of his increased power and financial resources is to buy new, rare, and expensive kinds of meat.” With these facts before us, it is difficult to accept the assumption that dietetic customs afford any indication of the food requirements of the body. To the physiologist such a view does not appeal, since there is a lack of any scientific evidence that carries conviction.

But it may be asked, is not appetite a safe guide to follow? Do not the cravings of the stomach and the so-called pangs of hunger merit consideration? Is it not the part of wisdom to follow inclination in the choice and quantity of our food? Can we not safely rely upon these factors as an index of the real needs of the body? If these questions are to be answered in the affirmative, then it is plain that a study of dietetic customs will tell us definitely how much food and what kinds of food are required daily to supply the true wants of the body. There are writers who claim that instinct is a perfectly safe guide to follow; that it is far superior to reason; but it is to be noticed that most of these writers, if they have any physiological knowledge to draw upon, are sooner or later prone to admit that the body has certain definite needs which it is the purpose of food to supply, with the added implication that any surplus of food over and above what is necessary to meet these demands is entirely uncalled for. Thus, one such writer states that “the man in the street follows his God-given instincts and plods peacefully along to his three square meals a day, consisting of anything he can find in the market, and just as much of it as he can afford, with special preference for rich meats, fats, and sugars.” Yet this same writer, a little later, emphasizes the fact that “every particle of the energy which sparkles in our eyes, which moves our muscles, which warms our imaginations, is sunlight cunningly woven into our food by the living cell, whether vegetable or animal. Every movement, every word, every thought, every aspiration represents the expenditure of precisely so much energy derived from food.” Why, then, would it not be wise to ascertain how much energy is so expended, on an average, during the day’s activity and govern the intake of food accordingly? Why not apply an intelligent supervision in place of following an instinct which, in the words of the author just quoted, leads one on to consume “anything he can find in the market and just as much of it as he can afford”? Truly, if dietetic customs and the habits of mankind are the results of instinct working in this fashion, there cannot be much value in the data obtained by observing the quantities of food mankind is in the habit of eating. Dietary standards based on such observations must be open to the suspicion of representing values far above the actual needs of the body.

Habits and cravings are certainly very unreliable indices of true physiological requirements. Man is constantly acquiring new habits, and these in time become second nature, forcing him to practise that which he has become accustomed to, regardless of whether it is beneficial or otherwise. The celebrated philosopher, John Locke, in his essay on education, says: “I do not think all people’s appetites are alike . . . but this I think, that many are made gourmands and gluttons by custom, that were not so by nature; and I see in some countries, men as lusty and strong, that eat but two meals a day, as others that have set their stomachs by a constant usage, like Larums, to call on them for four or five.” Again, the so-called cravings of appetite are largely artificial and mainly the result of habit. A habit once acquired and persistently followed soon has us in its grasp, and then any deviation therefrom is very apt to disturb our physiological equilibrium. The system makes complaint, and we experience a craving, it may be, for that to which the body has become accustomed. There has thus come about a sentiment that the cravings of the appetite for food are to be fully satisfied, that this is merely obedience to nature’s laws. In reality, there is no foundation for such a belief; any one with a little persistence can change his or her habits of life, change the whole order of cravings, thereby indicating that the latter are essentially artificial, and that they have no necessary connection with the welfare or needs of the body. The man who for some reason deems it advisable to adopt two meals a day in place of three or four, at first experiences a certain amount of discomfort, but eventually the new habit becomes a part of the daily routine, and the man’s life moves forward as before, with perfect comfort and without a suggestion of craving, or a pang of hunger. Dietetic requirements, and standard dietaries, are not to be founded upon the so-called cravings of appetite and the instinctive demands for food, but upon reason and intelligence, reinforced by definite knowledge of the real necessities of the bodily machinery.

The standards which have been adopted more or less generally throughout the civilized world, based primarily on the assumption that man instinctively and independently selects a diet that is best adapted to his individual needs, are open to grave suspicion. The view that the average food consumption of large numbers of individuals and communities must represent the true nutritive requirements of the people is equally untenable. Naturally, there is general recognition of the principle that food requirements are necessarily modified by a variety of circumstances, such as age, sex, body-weight, bodily activity, etc. It is obvious that the man of 140 pounds body-weight needs less proteid than the man of 170 pounds, and that the man who does a large amount of physical work demands a larger calorific value in his daily diet, i. e., more carbohydrate and fat, than the sedentary individual. The growing child, in proportion to his body-weight, plainly needs more proteid for the upbuilding of tissue, and there are many conditions of disease where special dietetic treatment is undoubtedly called for. Our contention, however, and one which we believe to be perfectly justifiable, is that the true food requirements of the body, under any conditions, cannot be ascertained with any degree of accuracy by observations of what people are in the habit of eating; that customs and habits are not a safe index of true physiological needs. On the contrary, we are inclined to the belief that direct physiological experimentation, covering a sufficient length of time and with an adequate number of individuals, will prove far more efficient in affording a true estimate of the quality and quantity of food best adapted for the maintenance of good health, strength, and vigor.

Before considering these latter points, it is interesting to note, in passing, that during the last four centuries many thoughtful men have called attention to the apparent excessive use of food. There seems to have been in many quarters a more or less prevalent opinion that custom and habit were leading people on to methods of living, which were not in accord with the best interests of the community. It must be remembered, however, that arguments of this kind, even fifty years ago, could have been founded only on general observation and the application of common sense, since there were then no sound physiological data on which to predicate an opinion, or base a conclusion. Still, there were men of authority who attempted to lay before the people a proper conception of the temperate use of food. We have not the time here to consider many of these pleas, but I venture to call attention to the somewhat celebrated book published by the physician Thomas Cogan in 1596, under the title “The Haven of Health,” and dedicated “to the right honorable and my verie good lord, Sir Edward Seymour, Knight and Earl of Hertford.” Under the subject of diet, this old-time writer says: “The second thing that is to be considered of meates is the quantitie, which ought of all men greatly to be regarded, for therein lyeth no small occasion of health or sickness, of life or death. For as want of meate consumeth the very substance of our flesh, so doth excesse and surfet extinguish and suffocate naturall heat wherein life consisteth.” Again, “Use a measure in eating, that thou maist live long: and if thou wilst be in health, then hold thine hands. But the greatest occasion why men passe the measure in eating, is varitie of meats at one meale. Which fault is most common among us in England farre above all other nations. For such is our custome by reason of plentie (as I think) that they which be of abilitie, are served with sundry sortes of meate at one meale. Yea the more we would welcome our friends the more dishes we prepare. And when we are well satisfied with one dish or two, then come other more delicate and procureth us by that meanes, to eate more than nature doth require. Thus varietie bringeth us to excesse, and sometimes to surfet also. But Phisicke teacheth us to faede moderately upon one kinde of meate only at one meale, or at leastwise not upon many of contrarie natures. . . . This disease, (I mean surfet) is verie common: for common is that saying and most true: That more die by surfet than by the sword. And as Georgius Pictorius saith, all surfet is ill, but of bread worst of all. And if nature be so strong in many, and they be not sicke upon a full gorge, yet they are drowsie and heavie, and more desirous to loyter than to labor, according to that old maeter, when the belly is full, the bones would be at rest. Yea the minde and wit is so oppressed and overwhelmed with excesse that it lyeth as it were drowned for a time, and unable to use his force.”

Cogan likewise makes some interesting statements regarding the effects of custom on the consumption of proteid food, especially meats. Quoting further from this author: “The fourth thing that is to be considered in meats is custome. Which is of such force in man’s bodie both in sicknesse and in health, that it countervaileth nature itselfe, and is therefore called of Galen in sundry places, an other nature. Whereof he giveth a notable example, where he sheweth that an olde woman of Athens used a long time, to eate Hemlocke (which is a ranke poison) first a little quantitie, and afterwarde more, till at length she could eate so much without hurt as would presently poison another. . . . So that custome in processe of time may alter nature.” Finally, we may quote one last saying of Cogan’s, because of the good sense and wisdom displayed in the sentiment, as true to-day as when it was written more than three hundred years ago: “Neither is it good for any man that is in perfect health, to observe any custome in dyet precisely, as Arnoldus teacheth upon the same verses in these wordes: Every man should so order himselfe, that he might be able to suffer heate and cold, and all motions, and meats necessary, so as he might change the houres of sleeping and waking, and his dwelling and lodging without harme: which thing may be done if we be not too precise in keeping custome, but otherwise use things unwonted. Which sentence of Arnoldus agraeth verie well to that of Cornelius Celsus: He that is sound and in good health, and at libertie, should bind himselfe to no rules of dyet. To need neither Phisition or Chirurgion, he must use a diverse order of life, and be sometimes in the countrie, sometime in the towne, sometimes hunt, and sometime hawke. But some man may demand of me how this may agree with that saying of the scholar of Salernus ‘if you would be free from physicians, let these three be your physician, a cheerful mind, rest, and a moderate diet.’ Whereunto I answer, that a moderate dyet is alwaies good, but not a precise dyet: for a moderate diet is, as Terence speaketh in Andria: To take nothing too much: which alwaies is to be observed. But if a man accustome himselfe to such meats and drinks as at length will breed some inconvenience in his bodie, or to sleepe or to watch, or any other thing concerning the order of his life, such custome must naedes be amended and changed, yet with good discretion, and not upon the sudden: because sudden changes bring harme and weaknesse, as Hippocrates teacheth. He therefore that will alter any custome in dyet rightly, must do it with three conditions, which are expressed by Hippocrates. Change is profitable, if it be rightly used, that is, if it be done in the time of health, and at leisure, and not upon the sudden.”

This noteworthy book written by Cogan was preceded by the writings of Louis Cornaro, the Venetian, who forty years before had published the first edition of his celebrated book, “The Temperate Life,” and who was a most ardent advocate of the benefits to be derived by living temperately, especially in matters of diet. The simple diet which served for the nourishment of the oldest peoples of Syria, Greece, Egypt, and of the Romans when they were at the height of their prosperity and culture, was advocated by Cornaro as conducing to longevity, better health, and greater comfort of mind and body. Himself a striking example of the effects of a reasonable abstinence in diet (the last edition of his book having been written at the age of ninety-five), his teachings have continued to attract attention down to the present day; and although we have no values in grams or calories expressive of his average food consumption, it is quite evident that Cornaro lived a very abstemious life, eating little of the heavier articles of diet common to his time and country. It is perhaps not strictly physiological to refer to these cases, yet they have value as representing a sentiment, common to the centuries now passed, that benefit was to be derived by mankind from greater care in the taking of food; that prevalent customs and habits were leading the people into intemperate modes of life, and that these were surely tending toward the physical and mental deterioration of the nation. We may attach much or little weight to these conclusions, but there is a certain degree of significance in the views, current then as now, that dietetic customs and habits have no real connection with bodily requirements.