Savages are reputed to have eaten the hearts of their enemies in order to acquire their courage. Civilized men, even scientists until very recently, believed that we should eat the muscles of the ox in order to acquire the strength of the ox. But I am not aware that anybody has ever advocated or practised eating of brains in order to benefit mentally.
Another superstition that seems even less plausible did arise, and is still believed in by some people; it is that fish is a brain food. This unwarranted belief was founded upon the somewhat accidental discovery that both the human brains and the meat of fish contain phosphorus. As a matter of fact many other foods are now known to be richer in phosphorus than fish, whereas phosphorus is a very minor element in the composition of brain substance.. None the less the incomplete knowledge of the early chemists gave rise to the belief in fish as brain food, and also to a slogan of the early German materialists who said “Keine Phosphor, keine Gedenken.””No phosphorus, no thought.”
The Physiology of the brain and the function of thinking are much more complex matters and less comprehended by science than are the physiology of the muscles and the function of muscular exercise.
The brain is composed chiefly of protein, but there is also a little highly specialized fatty substance known as lecithin, which is also present in egg yolks. As the action of the muscles does not consume its substance, so the action of the brain does not consume its substance, but, whereas muscular action consumes a very substantial quantity of food fuel, brain action does not consume any substance in quantities that science has been able to measure.
Yet brain action does require, perhaps we should say, results in an increased flow of blood to the brain. This blood is arterial as it flows to the brain and venous blood when it leaves the brain, showing that chemical changesoxidation at leastdo take place. That the effect of mental work in increasing oxidation cannot be measured, as can the effects of physical work, may merely be due to the fact that the brain forms only two per cent of the weight of the body, hence the effect of its labors would be too small to notice in comparison with the total metabolism going on in thc body. Thus a man thinking with relaxed muscles would seem to show less metabolism than another who sat apparently still but with tensed muscles. For these reasons the amount and nature of food required to produce thought can-not be measured and hence the belief has arisen that mental work does not consume food at all. This conclusion can at present be neither proven nor disproven, and we cannot state what is the exact purpose or effect of this extra flow of blood during brain activity, but that it has a purpose, we cannot doubt. Moreover, we do know that anything that interferes with the flow of blood to the brain, or any impairment of any such quality of that blood will interfere with brain action and reduce mental efficiency.
Some inference might be made as to the nature of essential “brain food” from the fact that a lack of one of the vitamines causes the dull sleepiness which ends in paralysis, as observed in pigeons and other experimental animals. It is probable that there are essential substances, minute in quantity, which are consumed in brain activity and the lack of which may cause mental inefficiency, insanity, and probably death. This problem science in the future may yet unravel.
No appreciable amount of bulkier food sub-stances such as ordinary proteins, carbohydrates and fats are concerned in brain activity. The brain wastes the slowest of any organ or tissues (with the exception of the bones) during fasting or starvation. Nor is the brain substance materially impaired by fasting. Barring the disturbing elements of the sensation of hunger which in fasting largely disappears after the first few days, the brains seem to work very well without the usual food supply. Upton Sinclair wrote a play during a two weeks’ fast. Dr. Benedict re-ports that a professional faster was in first class mental condition at the end of a thirty days’ fast and made a speech in which he gave evidence of a keen and wide-awake mind.
To take up more practical considerations, we find that many of the world’s greatest thinkers are light eaters and attribute their superior mental efficiency, in part at least, to their abstemious diet. Thomas Edison, whose record for long hours of high grade mental work has never been surpassed, insists that his capacity for a twenty-hour working day is due to his light eating habits, and his abstinence from alcohol and stimulants.
The heavy eater is unquestionably less efficient mentally than the man who eats just enough to maintain a minimum body weight and supply the energy for his physical activities. More particularly the effect of over-eating upon brain efficiency can be observed immediately after the eating of a heavy meal. In addition to the more general effects of over-eating we have here the specific effect of the withdrawal of the blood sup-ply from the brain to the digestive organs; the result is a lazy or sleepy feeling.
So important is this effect of the heavy meal upon the mental efficiency that it is generally recognized by efficiency experts who deal with high grade mental workers. One such efficiency engineer, in handling a large force of buyers for a firm in New York, laid down as a first rule that they should not have lunch before one o’clock; a second rule was that they should not consummate any important deal after lunch. In other words they should not do important business at all on a full stomach. In this manner he circumvented the practice of ‘salesmen who were in the habit of taking his buyers out to lunch, giving them a good feed and then, over coffee and cigars, while they were in good humorin other words, robbed of their mental alertnessputting across a good deal for the salesman, but a poor deal for the buyer’s house.
The digestion of food itself consumes energy, as I have elsewhere pointed out; it increases the total activities of the body as measured by the amount of oxygen consumed, but these increased activities, unlike those of exercise, seem to deaden rather than to stimulate mental activity.
The effects of a continuous light diet upon the mental power were observed in the case of the Y. M. C. A. College men whose physical tests on reduced portions we have already recorded. These men while on half their former food sup-ply maintained a ranking in their college grades that averaged about two per cent better than their previous college records, with the unlimited heavy diet, or the records of fellow classmen not on a reduced diet. Some detailed psychological tests seemed to show a decrease of certain mental powers, but there was no change sufficient to be observed by the men or their associates or that seriously interfered with their intellectual powers.
In their diaries many of the men remarked they felt freer from logginess and dullness, and more mentally fit; others complained that their increased hunger made them restless and disturbed in their studies.
Remember that these men were living on an extremely restricted diet, considering the amount of physical exercise they were taking. The. probable best results in mental as well as physical efficiency would be a happy medium of nutrition between the over-eating habits of the average man, and these half rations of wartime experimenters.
While there is probably no need, in ordinary life, of the extreme dietetic restrictions of these experimental subjects, yet unquestionably light eating habits are essential for those who wish to prolong their lives and do superior mental work. It is equally important for the mental worker to arrange the proportioning of his meals so that his chief labors of the day will not come during those hours when he is digesting his chief food supply for the day.
Either of the following plans will be suited to the worker whose mental labors are performed during ordinary office hours:
No Breakfastor at most nothing more than a cup of hot water, flavored, if desired, with a little milk or fruit juice. Or very light Breakfast of fruits.
Moderate Lunch, such as light sandwiches, Whole Wheat Bread if possible. Milk Salad
Full Dinner at 6 P.M.
Moderate Breakfastsuch as Fruit, fresh or evaporated. Light Cereals Milk or Eggs Whole Wheat Bread and Butter
At Noontake a recreational walk Or at most take nothing more than a Glass of Milk An Egg-nog, or Fruit Juice at a Soda Fountain.
Full Dinner at 6 P.M.
PLAN III. Begin the day with some fairly active exercises, ending in a brief walk, if convenient. After a brief rest take a hearty breakfast.
Breakfast: This meal should be the heartiest meal of the day. You can be assured of’ an appetite for it, if you follow the entire regimethat is, go to bed at least moderately hungry. This meal can consist of: Eggs or meat, as desired. Potatoes prepared to suit the taste or whatever other vegetable may appeal to you. Salad, if desired. Whole Wheat or hot Corn Bread and Butter.
At one o’clock, or five or six hours after you break-fast, take a moderately hearty meal, depending entirely upon your appetite. It should not be as hearty as the morning meal. Eggs, if desired. Vegetables or Salad. Whole Wheat Bread and Butter. Sweet Fruits as dessert.
No evening meal.
If you make milk a part of your diet, take a pint or whatever quantity of milk you may desire at this time. When taking milk it is better to take a glass at a time and allow a few minutes to intervene between glasses. Remember, don’t drink milk; “eat” it, as previously described.
Mental workers whose work need not be con-fined to the usual office hours, very frequently do their best work when other people are sleeping, either by sitting up at night, or preferably, by forming a habit of early rising. For such workers I suggest either of the following daily food regimes, though I strongly recommend the early rising habit.
Rise very early, say from 4 to 6 A.M.
Take a glass of hot water or a little fruit.
Work steadily without further food until the important creative work of the day is done, then partake of a moderate meal.
Devote the afternoon to physical recreation, or lighter work.
Eat supper early and spend the evening in mental recreation, or light mental work.
Go to bed early.
Rise late, 8 to 10 A.M. Take vigorous morning exercise, followed by a bath and eat moderate late breakfast, or early lunch.
Work at creative work or other occupation during the day without further eating.
Have. full dinner rather early in the evening. Then spend at least two hours in mental recreation.
After the meal has been digested, settle down for the creative work of the night and work as late as the mind will function vigorously. Sleep the next morning till you are fully rested.
Let me say in conclusion that while science has not discovered any particular brain foods, both science and practical experience teach us the great importance of maintaining a high degree of bodily efficiency as the basis of mental efficiency. The rules for mental efficiency are merely the rules for correct living generally; physical efficiency, health and long life can all be attained on a program of living that develops the best brain power. Most people are dull mentally because they are stuffed up from over-eating and under exercise. Either proper eating or proper exercise will benefit mental efficiency, but a proper balance of both will attain the best results of all.