Physiological economy in nutrition, with special reference to the minimal proteid requirement of the healthy man / an experimental study

Tuesday, May 24, 1904.

Breakfast.—Orange 100 grams, baked potato 138 grams, butter 5 grams, coffee 150 grams, sugar 14 grams.

Lunch.—Celery soup 150 grams, farina croquette 91 grams, syrup 48 grams, boiled onions 110 grams, potato 200 grams, stewed prunes 113 grams.

Dinner.—Tomato soup 150 grams, farina croquette 107 grams, syrup 48 grams, potato 200 grams, spinach 180 grams, cream pie 140 grams.

NITROGEN BALANCE.—Bellis.

Average Intake.

The Physical Condition of the Subjects.

Having considered the marked decline in the extent of proteid metabolism which these subjects have exhibited for a period of five months, and having shown the possibility of their maintaining body-weight and nitrogen equilibrium on a low proteid intake, coupled with a relatively small amount (low fuel value) of non-nitrogenous food, it is appropriate to consider next their physical condition under this changed mode of living. So much has been written upon the necessity of a rich proteid diet, with a corresponding rate of proteid metabolism, for the maintenance of bodily strength and vigor, that it becomes a question of vital importance to obtain data bearing upon the effect of a lowered proteid intake upon bodily strength. If, as is so widely believed, diminishing the daily proportion of proteid food below the standards set by Voit and other physiologists will result in a weakening of the muscles of the body, in decreasing the strength, vigor, and endurance of the individual, then obviously physiological economy in this direction would in the long run be uneconomical, and indeed injurious. The maintenance of body-weight and of nitrogen equilibrium on a small amount of proteid food would count for little, when compared with a gradual loss of bodily strength and vigor.

It was truly a great surprise when the systematic strength tests applied month after month to the soldiers indicated a marked gain in muscular power, which seemingly increased as the rate of proteid metabolism diminished, coincident with the decrease in the amount of proteid food fed. The dynamometer tests were applied primarily to make sure there was no falling off in strength, and when the marked gains already referred to were recorded, it was thought at first that they must be the result mainly of the systematic training the soldiers were undergoing in the gymnasium. Undoubtedly, this daily training, with the more regular and systematic methods of living, did contribute in some measure to the beneficial results obtained, but as the improvement and general gain in strength became more and more apparent, it was equally clear there were other factors involved than mere training.

The opportunity presented by the present subjects therefore was particularly desirable. These men had been in training for many months, some of them for several years, and naturally had acquired a high degree of proficiency in all kinds of athletic work, in the handling of themselves and in the handling of the apparatus, by use of which the strength tests are made.

The tests, etc., were applied exactly in the same manner as in the case of the soldier detail, description of which will be found on pages 259 and 260.

The following tables give the results of the tests—made at the Yale Gymnasium, and reported by Dr. Anderson—from January to June, for the eight men. It will be noted, however, that the record of Mr. Bellis is incomplete. This was owing to an injury to his hand, which prevented his working with the apparatus during the months of May and June.

The results presented by these tables are very important and suggestive. Every man, without exception, showed a decided improvement in his muscular power as measured by the strength tests. With many of the men the gain was progressive, with others there was noticeable—as in the case of W. L. Anderson and G. W. Anderson in the March test—a drop in some one test. This could generally be explained by some temporary cause. Thus, the March test taken by W. L. Anderson was at a time when he was under great strain in connection with an intercollegiate meet, etc. However, it is clear from the figures presented that all these men, though living on a greatly reduced amount of proteid food, and with certainly no increase in the quantity of non-nitrogenous food, showed at the end of the experiment a decided gain in muscular power. Note for example the great gain in strength shown by Schenker; in January his dynamometer tests, etc., indicated a total of 5728, while at the close of the experiment in June his record was 7135. Again, Bellis increased from 5993 to 8165, and W. L. Anderson from 6016 to 9472. Further, the men all agree in the good effect the changed conditions have had upon them, and they have, without exception, been able to do their athletic work and maintain their athletic supremacy.

STRENGTH OR DYNAMOMETER TESTS.

Naturally, in the case of these men the gain in strength recorded cannot be assigned to systematic training. The only change in their mode of living which can in any sense be considered as responsible for the improvement is the change in diet. The main fact to be emphasized, however, is that these men—trained athletes, accustomed to living on relatively large amounts of proteid food—for a period of five months reduced their intake of proteid food more than fifty per cent without loss of bodily strength, but, on the contrary, with a marked improvement in their muscular power.

Most striking is this gain in strength when compared with the very marked decline in the rate of proteid metabolism. Thus, in the case of Jacobus, the excretion of metabolized nitrogen was reduced to 7.43 grams per day as the average for the last two months of the experiment, yet his strength test showed an increase from 4548 in January to 5667 for June. Further, it must be recalled that an excretion of 7.43 grams of nitrogen means the metabolism of only 46.4 grams of proteid matter. Similarly, in the case of Donahue, a very active man whose work on the Varsity basket-ball team called for vigorous exercise, his strength test rose from 4584 to 5917 on a daily diet which led to the metabolism of only 7.39 grams of nitrogen per day, or about 46 grams of proteid matter. Further, Donahue frequently referred to the far greater freedom from fatigue he experienced on the low proteid diet, and he was clearly conscious of a distinct improvement in his physical condition.

The following letter from Dr. Anderson, the Director of the Yale Gymnasium, gives his estimate of the men at the end of the first three months of the experiment:

It must be remembered that this letter from Dr. Anderson was written after the March strength test was taken, and prior to the test of April 20. Dr. Anderson was not in New Haven at the close of the experiment, consequently it was not possible to obtain his estimate of the men at that date, but there can be no question that there was a distinct improvement from the middle of April to the middle of June; certainly as marked as the improvement from the beginning of the experiment in January, to April 12, the date of Dr. Anderson’s letter.

Finally, attention may be called to the photographs of Messrs. Stapleton, Bellis, and W. L. Anderson, which are introduced primarily to show the physical makeup and muscular development of the men composing this student group. The photographs of Stapleton were taken in April, 1904, after he had been under experiment for three months. The photographs of Bellis and W. L. Anderson were taken prior to the experiment. They all afford a good illustration of the highly developed muscular mechanism of different types, with a corresponding adaptability for different lines of muscular effort.

Reaction Time.

Through the courtesy and kind co-operation of Dr. Charles H. Judd, in charge of the Yale Psychological Laboratory, these students were subjected to the same careful tests during the five months of their experiment as were applied to the soldier detail. The results which are presented in the following report, kindly prepared by Dr. Judd, indicate quite clearly that there was no general nervous change in the reactors as a result of the low proteid diet. The data presented by Dr. Judd in this connection will be found in the accompanying tables, which, while indicating no noticeable improvement in the nervous condition of the men, make it quite plain that no deterioration whatever occurred as the result of the lowered proteid metabolism.

Report on Reaction.

Reaction tests with the group of University students were conducted in essentially the same way as were the reaction tests with the soldiers. Details in regard to the method and apparatus employed need not be repeated. They can be found on pages 274 to 276.

Two new tests were added to the regular reaction determinations. One of these consisted in taking a record of the number of taps which could be executed in ten seconds. The reactor was seated before a table on which was fastened a telegraph key. He held the key between his thumb and first two fingers, and at a given signal began tapping as rapidly as possible until told to stop. Each time he tapped he closed an electric circuit. The current thus made was carried through a marker which indicated on a smoked paper each make and break at the key. A time line from a rod vibrating at the rate of once every twentieth of a second was traced on the smoked paper parallel with the marker record. By a comparison of the time line with the marker record, it was easy to determine the number of taps made in ten seconds. At first, the number of taps per second were counted, but the results showed such uniformity from second to second on a given day that only the net results for the whole ten seconds are given in the tables.

The second test added to the reaction tests was undertaken to determine the steadiness of the subjects. Two brass rods 40 cm. long were held in a vertical position at a distance of 7 mm. from each other. The subject took in his right hand a brass rod 40 cm. long and 5 mm. in diameter and tried to pass the end of this rod up and down between the vertical rods without touching them. The subject’s relation to the vertical rods may be further defined by saying that he stood directly in front of them and reached out nearly at arm’s length. The vertical rods were at about the height of his chest. In order to get a record of the accuracy with which the subject moved the hand-rod up and down without touching the vertical rods, the vertical rods and the hand-rod were connected with the two poles of an electric circuit. Whenever they touched they closed the circuit, and a marker placed in the same circuit recorded the fact on a smoked paper record. The time was recorded in parallel with this record, so that any long continued contact could be measured. For the most part, contacts were only of very brief duration. In reporting the results of this test, every contact made while passing the rod once downward and once upward is counted as at least one. Continued contacts are recorded as two, three or more, according to the period of duration. Where there are such added counts because of continued contacts, a second quantity is given in the tables after the first. This second quantity, which is enclosed in parenthesis, indicates merely the number of contacts without reference to whether they are long or short.

No special comments are necessary to explain the tables. Tables 1-5 report in sigmas, or thousandths of a second, the average time of ten reactions on the date, and for the subject, indicated. In the third column, is the mean variation for the series of ten reactions.

Table 6 shows the general averages by the month for a given individual, and in the sixth column the general average of all the determinations for each reactor. The fourth column in each of the earlier tables shows how much the results of a given day vary from the final general average. All the tables give, at the bottom, group averages whenever the full series is present.

Table 7 gives the number of taps executed in ten seconds at each successive test. The dates are not given in detail, but are the same as those of the reaction tests.

Table 8 gives the monthly averages of taps.

Table 9 presents the results of the steadiness tests.

The three sets of results, namely, those from reaction, tapping, and steadiness, differ from each other. On the whole, the reactions grow longer; the tapping varies, but shows neither decided improvement nor deterioration; while steadiness improves very decidedly.

The comment made on the results obtained with the soldiers applies here so far as the reaction tests are concerned. These tests were not repeated with sufficient frequency to reduce the reaction to automatic performance.

The tapping is such a simple performance that improvement is not to be expected. The absence of any general improvement or deterioration argues for an absence of any general nervous change in the reactors.

The improvement in steadiness is in part at least, probably in very large measure, due to the fact that the subjects became more familiar with the test and approached it with less of the embarrassment which attends a new and unfamiliar test.

The lengthening of the reaction times indicates a less intense concentration of the subject upon the work in hand. The slightest relaxation of attention puts the subject behind in responding to the signal. It was clear to superficial observation, especially in certain individual cases, that the subject was giving less attention in the later experiments. This lack of concentration is not obviously related to the changes in diet. Indeed, the fact that no corresponding falling off appears in the tapping would seem to argue that the lack of attention in the reaction tests was not due to deep-seated nervous conditions, so much as to growing impatience on the part of the reactors with the ordeal of being tested. The tapping experiment is less likely to be affected by lack of interest on the part of the subject, because here the subject is called upon to be constantly active, and there is no such opportunity for attention to lapse as is furnished by the intervals which intervene between successive reactions. The tapping is accordingly perhaps the best series on which to base final judgment as to the nervous condition of the men. Here, there appear the variations which show in any ordinary series, but there is no steady improvement through growing familiarity with the test, nor any laxness of attention to produce relatively unfavorable results.

Mr. Steele and Dr. McAllister are largely responsible for the actual collection of the data on which this report is based.

(Signed) C. H. Judd.

TABLE 1.—February, 1904.

TABLE 2.—March, 1904.

TABLE 3.—April, 1904.

TABLE 4.—May, 1904.

TABLE 5.—June, 1904.

TABLE 6.

TABLE 7.

TABLE 8.

TABLE 9.

General Summary.

It is quite evident from a study of the results obtained in the foregoing experiments that young, vigorous men of the type under observation, trained in athletics, accustomed to the doing of vigorous muscular work, can satisfy all the true physiological needs of their bodies and maintain their physical strength and vigor, as well as their capacity for mental work, with an amount of proteid food equal to one-half, or one-third, that ordinarily consumed by men of this stamp. As the results show, all these men reduced their rate of proteid metabolism in such degree that the amount of nitrogen excreted daily during the period of the experiment averaged 8.8 grams, implying a metabolism of about 55 grams of proteid matter per day.

In other words, these athletes were able to reduce their nitrogenous metabolism to as low a level as many of the men of the professional group and of the soldier group, and this with not only maintenance of health and strength, but with a decided increase in their muscular power.

Metabolized nitrogen per kilo of body-weight for all these men, with one exception, during the experiment amounted to 0.108 to 0.134 gram per day, fully as low as was obtained with the members of the soldier detail on their prescribed diet. It is clear, therefore, that physiological economy in nutrition is as safe for men in athletics as for men not accustomed to vigorous exercise. There is obviously no physiological ground for the use of such quantity of proteid food, or of total nutrients, as the prevalent dietary standards call for.

The athlete, as well as the less active man (physically), or the professional man, can meet all his ordinary requirements with an intake of proteid food far below the quantities generally consumed, and this without increasing in any measure the amount of non-nitrogenous food.