On the writer’s return to New Haven in the fall of 1903, he was surprised to find that his body-weight was practically the same as early in July. In the period between November, 1902, and July, 1903, the body had lost 8 kilos under the gradual change of diet, but from July to October, 1903, the weight had apparently remained stationary, from which it might fairly be assumed that the body had finally adjusted itself to the new conditions.
What now was the condition of the body as regards nitrogen metabolism? To answer this question the entire twenty-four hours’ urine was collected practically every day, from October 13, 1903, to June 28, 1904, representing a period of nearly nine months. This daily output through the kidneys was analyzed each day with special reference to the total nitrogen,[31] as a measure of the amount of proteid material metabolized. Total volume of the urine, specific gravity, uric acid, phosphoric acid, indican, and other points were also considered, the more important results being indicated in the following tables.
CHITTENDEN.
Scrutiny of the tables shows that during this period of nine months the body-weight was practically constant. The daily volume of urine was exceptionally small and fairly regular in amount, the average daily output for the nine months being 468 c.c. It is a noticeable fact that with a diminished intake of proteid food there is far less thirst, and consequently a greatly decreased demand for water or other fluids. Further, in view of the small nitrogenous waste there is no need on the part of the body for any large amount of fluid to flush out the kidneys. The writer has not had a turbid urine during the nine months’ period. With heavier eating of nitrogenous foods, an abundant water supply is a necessity to prevent the kidneys from becoming clogged, thereby explaining the frequent beneficial results of the copious libations of mineral waters, spring waters, etc., frequently called for after, or with, heavy eating. Obviously, a small volume of urine each day means so much less wear and tear of the delicate mechanism of the kidneys. Somewhat noticeable, in a general way, is the apparent relationship between the volume of the urine and the nitrogen output, in harmony with the well-known diuretic action of urea. The specific gravity of the urine shows variation only within narrow limits, the daily average for the nine months being 1027.
Uric acid is noticeably small in quantity, the average daily output for the nine months’ period, based upon the determinations made, being only 0.392 gram.
Chief interest, however, centres around the figures for total nitrogen, since these figures give for each day the extent of the proteid metabolism; i. e., the amount of proteid material broken down in the body each day in connection with the wear and tear of the bodily machinery. To fully grasp the significance of these data, it should be remembered that the prevalent dietary standards are based upon the assumption that the average adult must metabolize each day at least 16 grams of nitrogen. Indeed, that is what actual analysis of the urine indicates in most cases. If now we look carefully through the figures shown in the above tables, covering a period from October 13, 1903, to June 28, 1904, it is seen that the daily nitrogen excretion is far different from 16 grams. Indeed, the figures for nitrogen are exceedingly low, and, moreover, they vary little from day to day. The average daily output of nitrogen through the urine for the entire period of nearly nine months is only 5.699 grams.
For the first six months the average daily excretion amounted to 5.82 grams of nitrogen, while from April 12 to June 28 the average daily excretion of nitrogen was 5.40 grams, thus showing a slight tendency downward. On the whole, however, there is shown a somewhat remarkable uniformity in the daily excretion. Thus, the average daily excretion for the month of November was 5.79 grams of nitrogen, for the month of March 5.66 grams, thus showing very little difference in the output of nitrogen through the kidneys in these two periods, three months apart. In other words, the extent of proteid katabolism was essentially the same throughout the entire nine months, implying that the amount of proteid food eaten must have been fairly constant, and that the body had adapted itself to this new level of nutrition from which there was no tendency to deviate. There was no weighing out of food and no attempt to follow any specified diet. The greatest possible variety of simple foods was indulged in, and the dictates of the appetite were followed with the single precaution that excess was avoided. In other words, it was temperance in diet, and not prohibition. Yet it is equally true, in the writer’s case at least, that the appetite itself unconsciously served as a regulator, since there was, as a rule, no necessity to hold the appetite in check to avoid excess. Doubtless, the writer’s knowledge of the general composition of food-stuffs has had some influence in the choice of foods, and thereby aided in bringing about this somewhat remarkable uniformity in the daily output of nitrogen for such a long period of time on an unrestricted diet.
What now do the nitrogen figures show regarding the amount of proteid material metabolized each day? It will be remembered that the Voit standard calls for 118 grams of proteid or albuminous food daily, of which 105 grams should be absorbable, in order to maintain the body in a condition of nitrogen equilibrium, and in a state of physical vigor and general tone. This would mean a daily excretion through the urine of at least 16 grams of nitrogen. The daily output of nitrogen in the case under discussion, however, was 5.699 grams for a period of nearly nine months. This amount of nitrogen excreted through the urine means only 35.6 grams of proteid metabolized, or about one-third the amount called for by the Voit standard, or the standards generally adopted as expressing man’s daily requirement of proteid food. But was the body in nitrogenous equilibrium on this small amount of proteid food? Naturally, this question might be answered in the affirmative, on the basis of the constancy in body-weight for the period from October to June, but more decisive proof is needed. The question was therefore settled by a careful comparison of the income and output, in which all the food eaten was carefully weighed and analyzed, while the nitrogen of the urine and fæces was determined with equal accuracy. The first experiment of this character to be quoted is for the week commencing March 20, a period of six days.