The data presented show a marked improvement in March and June over the record made at the beginning of the experiment in January, except in the case of one subject, E. As Fisher states, the increased endurance observed can be ascribed only to dietetic causes, since no other factors of known significance could have aided in the result. The dietetic changes, as we have seen, consisted in a slight reduction of the total amount of food consumed daily, but with a large reduction of the proteid element, especially from flesh foods. It is significant, says Fisher, that the only man whose strength and endurance showed any decrease was E, “whose case was exceptional in almost all respects. His reduction in quantity of food, except for a spurt at the end, was less than of most of the men; his reduction in proteid, with the same exception, was the least of all; his reduction in quantity of flesh foods was the least of all.” He stands out conspicuously as the one man whose endurance failed to improve. The mental test carried out with the subjects pointed to “a slight increase in mental quickness,” but the adding test was too short to be of great value.

We see in these results another confirmation of the view that the welfare of the body is not impaired by a marked reduction in the amount of proteid food; on the contrary, benefit results in the increased efficiency which manifests itself in various directions. Physical endurance is an asset not to be ignored, and like the strength of an individual, it may well be fostered by the recognition and practice of a principle which seemingly has a firm physiological basis. Whether the fatigue poisons come from the excessive exogenous katabolism of proteids in general, or whether they are derived directly in a measure from flesh foods, need not be considered here; the main point is that by lowering the rate of proteid katabolism, which necessarily compels a reduction in the amount of flesh foods, there is a diminished quantity of nitrogenous waste floating about in the body. Further, we need not criticise too closely the method by which the reduction of food is accomplished; whether it be by encouraging mastication, with a view to better tasting and fuller enjoyment of the food, to the point of involuntary swallowing; or whether we follow natural taste and appetite, reinforced by the use of reason, with a full appreciation of the principle that the welfare of the body is best subserved by a quantity of food commensurate with true physiological needs.

In making this presentation of the true food requirements of the body as based on the results of physiological experimentation and observation, I am by no means unmindful of the dangers of underfeeding; but this is a condition comparatively rare. When occurring, as stated by Dr. Curtis, “it is either because of dyspepsia, in which case it really is involuntary, or comes from some silly notion born of a combination of innate mental crookedness and that ‘little knowledge’ that is a dangerous thing.” Overfeeding is the predominant dietetic sin, and with the prevailing dietary standards, as fixed by common usage, there is good ground for believing that it will continue for many years to come. Reason tells us, however, in the practice of our personal nutrition, to steer a middle course between physiological excess on the one side, and the minimal food requirement on the other. To quote again from Dr. Curtis,64 who has expressed the matter very forcibly, “The physiological chemist can easily draw a line on the Scylla (starvation) side of the channel. A dietary whereby the system gets less than it pays out is, obviously, a dangerous veer toward starvation rock. But on the Charybdis (stuffing) side, just as the whirlpool itself has no well-defined border, the channel boundary is not so easily marked. The case is exactly analogous to the stoking of a furnace. The proportion of ash to live coals is a telltale as to underfeeding, but not as to overfeeding. With undersupply of fuel the ashes overbalance the live coals, and the fire is thus foretold to be going out. But with an oversupply the fire simply burns the faster: all the fuel continues to be consumed; the more coal simply makes the more ash, so that equilibrium is not disturbed, although maintained at a higher level. To argue, therefore, that a given dietary is none too large, because the balance between the material receipts and expenditures of the economy is not upset, would be like saying that a given furnace-fire is certainly none too hot, since the ashes raked out of the fire-box just correspond to the amount of coal shovelled in. The same would be equally true of a slower fire consuming much less fuel. The philosophy of the matter is, then, to find the minimum of steam that will run the engine, and then maintain a fire somewhat hotter than the exact requirement, in order to run no risk of failure; or, to return to the metaphor already employed, the would-be careful liver must simply note how close to Scylla other voyagers have sailed with safety, and then steer his own bark accordingly.”

As one looks through the many careful dietary studies that have been made in recent years, it is easy to find striking illustrations of people, and communities of people, who have lived for long periods of time on dietaries so strikingly simple and meagre that it seems difficult at first glance to believe their daily needs could have been entirely satisfied. Yet, such observations are quite in accord with the facts we have been presenting, and they afford additional evidence that the artificial dietary standards that have been set up are widely at variance with the real requirements of the body for food. It may be quite true that many of the people referred to have been and are faddists, with peculiar notions regarding food, based on religious or other scruples, but that has no bearing on the main contention that they have lived for many years on amounts of food ridiculously small as compared with the ordinary customs of mankind. Thus, in Professor Jaffa’s report65 of investigations made among fruitarians and Chinese of California is an interesting account of a dietary study of a family of fruitarians, consisting of two women and three children. They had all been fruitarians from five to seven years, their diet being limited to nuts and fruit, except for the addition of celery, honey, olive oil, and occasionally a small amount of prepared cereal food. This family was in the habit of taking only two meals a day; at 10.30 in the morning and at 5 o’clock in the afternoon. The first meal always consisted of nuts and fruit, the nuts being eaten first. At the second meal, nuts were usually replaced by olive oil and honey. The nuts made use of were almonds, Brazil nuts, pine nuts, pignolias (a variety of pine nuts), and walnuts. Fruits, both fresh and dried, were used, the former including apples, apricots, bananas, figs, grapes, olives (pickled), oranges, peaches, pears, plums, and tomatoes. The dried fruits were dates and raisins.

On this limited dietary of raw, uncooked food, with a complete absence of the high-proteid animal foods, and the ordinary vegetables, legumes, etc., and without eggs or milk, this family, with three growing children, had lived all these years. Note now what Jaffa observed regarding their food consumption. The first subject, a woman 33 years of age and weighing 90 pounds, was studied for twenty consecutive days, all the food eaten being carefully weighed and its chemical composition determined. As a result, it was found that the average amount of food consumed per day was: proteid, 33 grams; fat, 59 grams; carbohydrate, 150 grams; with a total fuel value of 1300 calories. The other members of the family were studied in a similar manner, one of the children being the subject on two separate occasions. The table (on page 217), showing the average daily food consumption, gives a summary of the results obtained.

As Professor Jaffa states, the tentative dietary standard for a woman at light work calls for 90 grams of proteid daily, with a fuel value of 2500 calories. Both of these women were light in weight, and furthermore had no occasion to do much physical work; but even so, a daily consumption of only 0.8 gram and 0.52 gram of proteid, respectively, per kilo of body-weight, with the small calorific values indicated, represents a phenomenally small amount of food. And yet Jaffa, in referring to the woman with the lowest intake of food, states that even this small quantity of food, judging from the appearance and manner of the subject, “seemed sufficient for her needs, enabling her to do her customary housework and take care of her two nieces and nephew.” Regarding the children, it is stated that the commonly accepted American dietary standard for a child 13 years old and of an average activity calls for about 90 grams of proteid and 2450 calories. As is seen from the table, however, the 13-year-old girl consumed of proteid less than one-third, and of fuel value only about 60 per cent of the amount called for; yet, says Jaffa, “notwithstanding the facts brought out by this comparison, the subject had all the appearances of a well-fed child in excellent health and spirits.”

We need not consume time in discussing the details of this experimental study, though the facts are interesting and suggestive, for it is only the general question of proteid requirement and calorific value that has interest for us at present. The fact is perfectly clear that this family of fruitarians, young and old, were quite able to live and thrive on a diet, the value of which in proteid and calories was at as low a level as was attained in our experimental studies. The rock of starvation, however, was not touched or even sighted by the voyagers down this stream of nutrition. We may all agree that it would be preferable, as a rule, to acquire the proteids, fats, and carbohydrates of our diet from a greater variety of sources than did the fruitarians; we might well complain at a dietary so limited in quality; but the point to be emphasized is that the low intake of proteid and the low fuel value were quite adequate for meeting the needs of the body. “It is a difficult matter,” says Professor Jaffa, “to draw any general conclusions from the foregoing dietaries without being unjust to the subjects. It would appear, upon examining the recorded data and comparing the results with commonly accepted standards, that all the subjects were decidedly undernourished, even making allowances for their light weight. But when we consider that the two adults have lived upon this diet for seven years, and think they are in better health and capable of more work than they ever were before, we hesitate to pronounce judgment. The three children, though below the average in height and weight, had the appearance of health and strength. They ran and jumped and played all day like ordinary healthy children, and were said to be unusually free from colds and other complaints common to childhood.”

Turning now to a larger community,—the island nation of Japan,—whose exploits in war have recently attracted the attention of the civilized world, we find a people the great majority of whom have remained untouched by the prodigality of western civilization, and whose customs and habits still bear the imprint of simplicity and frugality. After the restoration of Japan and the reorganization of the government in 1867, much attention was directed to the methods of living and to the dietary habits of the people, with the result that during the last twenty-five years there have been slowly accumulating many important data bearing on the food consumption of the people. These have recently been brought together in an interesting volume by Kintaro Oshima, and published66 in the English language.

As is well known, the great majority of the people of Japan live mainly on a vegetable diet. It is also known to physiologists at least that Japanese dietaries are characterized by a relatively small amount of proteid, though since the passage of the Food Supply Act of the navy in 1884, the proteid-content of the navy ration has been decidedly increased. It will be interesting to note a few of the results collated by Oshima, and some of the conclusions that he draws from the data presented. The foregoing table shows a few of the more striking results of the dietary studies obtained with various classes of people, where the food used was largely vegetable, but generally with some admixture of fish or meat.

The figures presented, which represent the actual amounts of food consumed, with proper correction for the indigestible portion, show a much smaller intake of proteid than is common with European and American people; indeed, both proteid and fuel value are very much less than common practices call for among western peoples, even when due allowance is made for differences in body-weight. To quote from Oshima, “Probably the most interesting of the dietary studies are those with poorer classes, which comprise by far the larger part of the population. The dietaries of the miscellaneous class, including employees, prisoners, etc., consisted largely of vegetable foods and supplied on an average 59 grams of proteid and 2190 calories of energy per man per day.” Especially suggestive were the results of a study made with a military colonist, a type of man very common in Japan; in reality farmers who live at home, but have military drill at certain fixed times. The subject was carefully selected under advice of officers in charge of the district, and weighed 59.9 kilograms. His diet consisted solely of cereals and vegetables, being identical with that of the people in the rural districts of Japan. His daily food was found to be composed of 46.3 grams of digestible proteid, with a fuel value of 2703 calories.

Even more striking were the results obtained in a study of the dietary habits of three healthy natives of Formosa, employed as day laborers at the military hospital. They weighed respectively 60.9, 55, and 54.8 kilograms. The main portion of their diet was rice, supplemented, however, by a little salt fish, salted melon, spinach, ginger, and greens. The daily amount of proteid ingested was 48.0 grams (37.4 grams of digestible proteid), with a total fuel value of 1948 calories. A composite sample of urine covering seven days showed an average daily output of metabolized nitrogen of 6.93 grams, corresponding to a breaking down of 43.3 grams of proteid.

Especially interesting also is a series of experiments with professional men, reported by Oshima, in which attention was paid to nitrogen balance. The following table shows the essential results:

It is to be observed that in all of the above experiments, excepting two, the subjects gained nitrogen even with the low proteid intake and the small fuel value of the day’s food. Particularly noteworthy, in harmony with previous statements, are the results of the sixth and seventh experiments. In the sixth experiment, the subject was not able to maintain nitrogen equilibrium on a diet containing 36.8 grams of digestible proteid and having a fuel value of 1825 calories, but by raising the intake of carbohydrate food (seventh experiment) to 462 grams daily, thereby increasing the fuel value of the daily ration to 2200 calories (with a slight increase in the proteid incidental thereto), the body was able to change its previous loss of nitrogen into a gain; in other words, the added carbohydrate served as a protector of proteid.

The series of experiments as a whole, however, is to be considered in the light of additional data bearing on the dietary customs of a people who for generations have apparently lived and thrived on a daily ration noticeably low in its content of proteid, as well as low in its calorific value. As Oshima states, “It is probably fair to infer that the amount of proteid in the dietaries of the classes living largely on vegetable foods (and they constitute the larger part of the population) may not be very far from 60 grams per day,” or 45 grams of digestible proteid. It is reasonable to assume that the people live in this way from force of habit or of necessity, and we may agree with Baelz, a professor connected with the medical faculty of Tokyo University, “that their diet is sufficient from a physiological standpoint.” Doubtless a mixed diet, with a larger proportion of animal food, did their means readily permit, would offer some advantages from the standpoint of palatability and variety, but it is questionable if any material gain in health or strength would result. “It is sometimes remarked,” says Oshima, “that the peasants in the rural districts of Japan, living largely on vegetable food, are really healthier and stronger than people of the better classes, who live on a mixed diet, and the better physical condition of the former is commonly believed to be due to their diet.” This, however, is a difficult matter to decide, since there are so many other factors that are liable to play a part, such as the general conditions of life which are so widely different in the two classes.

It is plainly evident that the daily diet of the great bulk of the Japanese people has been characterized by a very low proteid standard, as contrasted with the standards and usages of the majority of European and American people. The fact is brought forward merely as confirmatory evidence, on a large scale, of the perfect safety of lowering the consumption of proteid food to somewhere near the level of the physiological requirements of the body. Generations of low proteid feeding, with the temperance and simplicity in dietary matters thereby implied, have certainly not stood in the way of phenomenal development and advancement when the gateway was opened for the ingress of modern ideas from western civilization. Many changes are sure to follow in the footsteps of the nation’s progress, and among these it is safe to prophesy that as public and private wealth, and resources in general, increase, the dietary of the people will gradually assume a more varied character with corresponding increase in volume. Whether such a change will prove of real benefit to the race, time alone can determine.

Having said so much concerning the Japanese, it is proper that a few additional statements should be made. The stature and general physique of the people could be advantageously improved. Is this a question of dietary, or is it connected with some condition of life on which the daily food has no bearing; or is it, perchance, a racial characteristic so deeply ingrained that conditions of environment are without noticeable influence? These questions cannot be definitely answered at present. Finally, we may call attention to the dietary changes inaugurated in recent years in connection with the new organization of the imperial army and navy. With a view to increasing the efficiency of the men, following the customs of other countries, an act was passed increasing the amount of proteid food in the navy dietary. Oshima’s report of the various steps taken to accomplish this end, with the results that followed, is interesting in several ways.

“A large part of the rice was to be replaced by bread, and meats were to be used liberally. The experience, during the first year that this ration was tried, indicated that bread and meat could not be advantageously substituted immediately for the rice, because most of the marines were unaccustomed to these food materials; consequently, a modification of the ration was introduced in 1885, whereby a rice-barley mixture was adopted in place of the bread. Barley was considered at that time as a better article of food than rice, on account of its higher proteid content, but later investigations showed that the digestibility of the nutrients of barley was small. In 1886, an effort was again made to substitute bread for the rice-barley mixture. In 1890, the ration allowance was reduced by one-fifth and an amount of money equivalent to the cost of the reduction in diet was given to each marine with which to buy accessory food according to his own choice. In 1898, the reduction was made one-tenth, instead of one-fifth as in previous years. In 1900, the cash allowance was abolished and a new ration adopted.” This ration contains about 150 grams of proteid (animal and vegetable food) and has a fuel value of over 3000 calories. In all of these changes, the proportion of rice was greatly reduced.

Probably, one of the chief reasons why persistent efforts were made to improve the dietary of the navy was the prevalence among the men of the disease known as beriberi. “While no satisfactory explanation as to the cause of the disease was offered, it was generally believed that there was some very close relation between the disease and the rice diet” (Oshima). During the years 1878–1883 inclusive, nearly 33 per cent of the marines suffered from beriberi. With the adoption of the new ration in 1884, in which a large part of the rice was replaced by bread and other articles, and with better hygienic conditions, this disease immediately began to disappear, and during the six years after the adoption of the new diet only 16 per cent of the marines were affected by the disease. Later on, hardly more than two or three cases a year were recorded. Advocates of a high proteid diet bring forward this illustration as an evidence of the danger connected with a lowered proteid intake; i. e., that the nutrition of the body will be impaired and diseases of various sorts liable to follow. Yet, Oshima is very careful to state, “It should be especially noted that here no attempt has been made to indicate the cause of beriberi or the relation between the disease and the diet.” That rice in itself can be a cause of the disease is not to be considered for a moment. Further, so far as any facts are concerned, the writer can see no ground for considering that a low rate of proteid metabolism has in itself any direct connection with the disease. From a dietary standpoint, it seems far more plausible to assume that the great restriction in variety of foods, so strikingly manifest in the dietary of the poorer people of Japan, results in a lack of some one or more elements which conduces to the disease, just as in scurvy the lack of fresh vegetables on long voyages was liable to be followed by an epidemic of this disease.

Consider the natural character of the dietary of the great bulk of the Japanese people, determined as it was by adverse financial circumstances. As Oshima states, “The rural population of the interior depends very largely or entirely upon a vegetable diet. Fish is eaten perhaps once or twice a month, and meat once or twice a year, if at all. The poorer working classes in the cities also use very little animal food. But the poorer classes in the city and the peasantry of the rural districts comprise nearly 75 per cent of the total population, and it is therefore safe to assume that this proportion lives chiefly, or wholly, upon vegetable diet. And this, it may be observed, means vegetarianism literally. The so-called lacto-vegetarianism is unknown in Japan. Cows are scarce, and milk and other dairy products are expensive, and such as are available are consumed almost entirely by the wealthier people in the cities.” It is also to be noted that the amount of fat in Japanese dietaries is very small. The reported data indicate that the usual vegetable dietaries contain only about 10 grams of fat per day, while even in the average mixed dietaries the amount rarely rises above 20 grams per day. In other words, the ordinary food of the Japanese was characterized by great lack of variety, and with such a preponderance of carbohydrate materials of a limited kind that it is easy to conceive of a possible dearth of some essential or accessory element, necessary for the preservation of that nutritive balance which aids in protection against disease.

If the resistance of the body to disease germs and toxic influences in general is really diminished by reducing the consumption of proteid food below the set dietary standards, then obviously here lies a tangible reason for the maintenance of a high proteid intake. I know of only one series of scientific observations that bears directly on this question. Dr. Reid Hunt of Washington has studied recently the power of resistance to the poison acetonitrile of animals kept for some time upon a reduced proteid diet. “My experiments,” says Dr. Hunt, “showed in all cases that the resistance was much increased.” In other words, the animals that had been fed a low proteid ration were able to endure a much larger dose of the poison than corresponding animals on their customary diet; “they resisted 2–3 times the ordinary fatal dose of acetonitrile.” This general subject, however, is obviously a very important one, and merits further experimental study under a diversity of conditions.

In conclusion, the facts here presented bearing on food requirements, especially those that relate to the need for proteid food, are seemingly harmonious in indicating that the physiological necessities of the body are fully met by a much more temperate use of food than is commonly practised. Dietary standards based on the habits and usages of prosperous communities are not in accord with the data furnished by exact physiological experimentation. Nitrogen equilibrium can be maintained on quantities of proteid food fully fifty per cent less than the every-day habits of mankind imply to be necessary, and this without increasing unduly the consumption of non-nitrogenous food. A daily metabolism of proteid matter equal to an exchange of 0.10–0.12 gram of nitrogen per kilogram of body-weight is quite adequate for physiological needs, provided a sufficient amount of non-nitrogenous foods—fats and carbohydrates—is taken to meet the energy requirements of the body.

The long-continued experiments on many individuals, representing different types and degrees of activity, all agree in indicating that equilibrium can be maintained indefinitely on these smaller quantities of food, and that health and strength can be equally well preserved, to say nothing of possible improvement. The lifelong experience of individuals and of communities affords sufficient corroborative evidence that there is perfect safety in a closer adherence to physiological needs in the nutrition of the body, and that these needs, so far as proteid food is concerned, are in harmony with the theory of an endogenous metabolism, or true tissue metabolism, in which the necessary proteid exchange is exceedingly limited in quantity. There are many suggestions of improvement in bodily health, of greater efficiency in working power, and of greater freedom from disease, in a system of dietetics which aims to meet the physiological needs of the body without undue waste of energy and unnecessary drain upon the functions of digestion, absorption, excretion, and metabolism in general; a system which recognizes that the smooth running of man’s bodily machinery calls for the exercise of reason and intelligence, and is not to be intrusted solely to the dictates of blind instinct or to the leadings of a capricious appetite.