The dietary standards that we have been considering are those that have been accepted generally since work of this kind was first begun. Some late experiments conducted at Yale University by Professor Chittenden and others, indicate that a much smaller amount of food, especially of proteid, may better serve the purposes of the body, than the larger amounts indicated in these standards. The experiments were carried out upon men representing three different classes of individuals. The first class was composed chiefly of professors and instructors. The second represented the moderate worker. The third class were trained athletes. The experiments covered a period of five months, and the proteid taken daily varied from about thirty-five to fifty grams per day, while the total number of calories yielded was from twenty-five to twenty-eight hundred a day. The general conclusion drawn from these experiments is that under ordinary conditions of life, with an ordinary amount of work, bodily health and vigor are maintained as well, if not better, on a minimum proteid diet than on the amount given in the generally accepted standards.
Some careful experiments and analyses recently made by the physiological chemist, Dr. Otto Folin, at the McLean Hospital, Waverly, Mass., indicate that about twenty grams of proteid represents the actual daily proteid wastes of an average sized man under ordinary conditions. That is, only about three-fourths of an ounce of proteid material is necessary per day in an adult to rebuild the nitrogenous tissue of the body that wears away through use.*
Such radical differences from standards found by long experience to give good results in health and strength must be considered very carefully before being accepted. But in this as in many other ways, we may be obliged to revolutionize our ideas of food.
We must not fail to distinguish between the amount of proteid required and the amount of food containing proteid. If, for example, meat be supplied containing 18 per cent of proteid (a fair average), a little more than a pound and a half of the meat will be required to furnish the four and a half ounces of proteid. Bread containing 9 per cent of proteid would be required to the amount of three pounds. Nearly two pounds and a quarter of eggs, with 13.1 per cent of proteid, or about eighteen eggs, would be necessary to supply four and a half ounces of pure proteid.
*See Report of the Lake Placid Conference on Home Economics. 1905, and American Journal of Physiology, March, 1905.
Taking the percentage composition from the accompanying table, calculate the amount of milk that would be required daily to furnish four and a half ounces proteid. How much potato would be required? How much corn meal?
Calculations: From the table, milk is found to contain 3.3% of proteid or 1 oz. contains .033 oz. protein. To furnish 4.5 ozs. would require 4.5/.033 = 136+ As a pound contains 16 ozs., 136 oz.=8 1/2 lbs. A pint of milk weighs about 1 lb., so about 4 1/4 quarts would be required to provide 4.5 ozs. of proteid. Potatoes as purchased contain 1.8% proteid. 4.5/ .018 = 250 250 oz. = 15 lbs. (aprox.) A bushel of potatoes weighs about 60 lbs., consequently about one peck of potatoes would be required. Corn meal contains 8.9% proteid and by the same calculations 3 lbs. 2 ozs. will be found to contain 4.5 ozs. of proteid.