Ejkmann,1 C. Funk, Th. B. Osborne,2 Lafayette B. Mendel,3 Hess4 and Goldman have done meritorious work along the vitamines and their relation to deficiency diseases. While the exact chemical composition of the vitamines has not, as yet, been established, they are divided into the following 3 varieties:

1. The fat soluble A. vitamine (or the antirachitic factor), contained principally in butter, the maize kernel; carrots; sweet potatoes.

2. The water soluble B. vitamine (or the antineuritic factor), contained in yeast, beans, cabbage, cane sugar, yolk of eggs, oranges, lemons, grape fruit.

3. The water soluble C. vitamine (or the antiscorbutic factor) contained in cabbage, tomatoes, oranges, and milk.

1 Ejkmann: Virchow's Arch., 1897,148, p. 528.

2 Th. B. Osborne: N. Y. State Journal of Medicine, July, 1920. 3 L. B. Mendel: N. Y. State Journal of Medicine, July, 1920. 4 Alfred Hess: N. Y. State Journal of Medicine, July, 1920.

All foods contain one or two, or three of the above designated substances, namely protein, carbohydrate, and fat. In order to find out the amount of food necessarily required for living, the physiologists have calculated how much of these three different classes we require, not saying how much bread, meat, potatoes, etc., but how much albumin, how much carbohydrate, or how much fat is required for a grown person each day. It has been found that a grown person uses up each day about:

120 gm. of albumin = oz. IV

500 gm. of carbohydrate = oz. XVII.

60 gm. of fat = oz. II.

2 1/2 to 3 quarts of water.

Besides these three essentially nutritive substances we utilize condiments and some alkaloid and alcoholic beverages (accessory foods). The condiments (pepper, table salt, onion, mustard, cinnamon, nut meg etc.) serve to increase the taste of the food and make it more savory. The latter (coffee, cocoa, tea, beer, wine, etc.) exert a stimulating effect and diminish the depressing act due to the process of digestion. While the alkaloidal substances (theobromin, caffein (trimethylxanthin) are as such without nutritive value, the alcohol must be counted as a nutritive substance. It furnishes 7 Cal. per 1 gm. If not taken in high concentration and in too large quantities it often helps nutrition, especially in diseased states.

Water contains many mineral ingredients not found in the food. While protein must exist in the food which any individual requires for living, in some way or another, and cannot be dispensed with, either the carbohydrate or the fat can be omitted without much injury. This is to say, one of these groups can replace the other without injury to the individual for a while, but the albumin is essential. The reason for that is that the protein is the foremost substance 2 in the body. Any tissue that is used requires albumin to build it up again. The fat which is taken in helps to build up the organism; it also produces heat. Heat is also furnished by the other substances, by the protein and the carbohydrates, but as a tissue builder the protein is necessary. From protein the organism can make glycogen, fat, or muscle, but the body cannot make protein out of the carbohydrate or the fat. That is why protein is the most essential substance.

Now the physiologists, especially Rubner - who was here not long ago - who has made a great many studies and deserves to be remembered, have tried to ascertain in what degree these substances can replace each other, and found that they do it corresponding to the amount of heat which they develop. Every kind of food taken into the body is oxidized in the system. We take in oxygen with the air, and the nutritive substances become oxidized. The more carbon a special kind of food contains, the more oxygen it can bind. The more carbon in the food, the more heat it can develop in burning up. The burnt up or oxidized compounds leave the body in the form of CO2 and H2O, through the lungs and kidneys.

It has been found that one gram (15 grains) of food material, if oxidized (burnt up) develops a certain amount of heat. I will explain how that is calculated. It has been arranged by the scientists to measure heat in this way: The idea is to know exactly how to estimate the heat. They have agreed to take as the measurement for one heat unit the amount of heat which is sufficient to increase the temperature of one cubic centimeter of water (16 grains) 1 degree Celsius. This is also designated as a small calorie (cal.).

In speaking of the heat values of food, however, we use great heat units, or great Cal. That means the amount of heat which is sufficient to raise 1 liter (1 quart) of water 1 degree C. Returning to the food values, it has been found that one gram of protein is sufficient to develop 4.1 Cal. In speaking of food calories, we do not say "great heat unit," or great Cal., but we mean that. It is written Cal.

Protein, 1 gm. develops......... 4.1 Cal.

Carbohydrate, 1 gm. develops. . . 4.1 Cal. Fat,1 1 gm. develops........... 9.3-9.5 Cal.

1 See.: C. A. Ewald: Diät und Diätotherapie. Berlin, 1915, p. 202.

Notice that the fat develops more than double the amount of heat, as compared with the others.

The way foods should represent each other is by their caloric value, excepting that we cannot eliminate protein. A certain amount of protein must be in any food, - but we can combine protein with carbohydrate (as present in most vegetable foods), or we can have protein and fat as represented by animal foods. If we should have someone live on protein and fat, we would say that the fat should be less than half the amount of carbohydrate required, for it contains so many more heat units.

Now it has been found that a man requires for one day about 2400 calories or on an average 30 - 40 Cal. per kilo an hour.

A man doing a considerable amount of work ordinarily consumes about:

It has been found generally that a grown person requires about 2500 heat units each day, or food which develops that number of heat units, when doing a moderate amount of work. If he works hard, he requires more, 3000 calories, or more. If he is in bed, he requires less. I have found that a patient in bed requires much less; he can exist on 1800 heat units without losing much flesh.

Smaller organisms require more heat units per kilo weight. This is due to their proportionately increased surface ratio, which increases the loss of heat. Infants require more than double the amount of calories per kilogram weight of the grown. This must be ascribed to the comparatively larger surface of the young and the act of growing. According to Heubner and Rubner1 the newborn (from the 2nd to the 18th week) consumes 100 Calories per kilo a day, later somewhat less. An artificially fed infant requires 120 Cal. per kilo a day.

1 Heubner & Rubner: Leitschr. f. Biologie, vol. 36, p. 1, and vol. 38, p. 315.