Personal hygiene and physical training for women

by Anna M. Galbraith

Standard Dietaries: The Maintenance Diet.—There is great need of standardization and of knowledge regarding the maintenance diet, first among physicians and then among the people in general, or scientific dietaries based on the nutritive value of foods. These are given in terms of proteins, carbohydrates, and fats, together with the aggregate energy of the nutritive value in each. This is the corner-stone of dietetics.

Dietetics is the science of feeding. It has to do with the necessities of the body and the ability of the food to meet these necessities in the various circumstances and conditions of life. The ultimate scientific knowledge concerning human nutrition should be to promote the healthful and economic use of food.

The problems to be dealt with are quite complex. These are: (1) changes in the economic conditions of the population; (2) changes in food production and food supply; (3) changes in the methods of preparing food.

In regard to the influence of the economic conditions of the people on the composition of their diet, it might be expected that a considerable decrease in the earning capacity of the poorer people, or an increase in the cost of foods, would be followed by a change in their diet. Everyday experience teaches that under such conditions the more expensive foods—meat, eggs, and milk—are reduced in the diet. These same foods are also rich in vitamins, so that a reduction here would, therefore, reduce the vitamin content of the dietary unless other dietary complements rich in vitamins, such as legumes, were introduced.

The value of any food as a source of heat and energy is measured by a bomb-calorimeter. The heat given off during the combustion is a measure of the latent or potential energy of the food. The kinetic energy of the food is the amount of heat developed by the proportion which is digested. The unit commonly used is the calorie, or the amount of heat which would be required to raise the temperature of 1 kilogram of water 1° C., which is about equal to that required to raise the temperature of 1 pound of water 4° F.

Heat Value and Digestibility of Foods.—One of the chief functions of food is to supply the body with heat and energy; the food must be capable of digestion and absorption. Herein lies the exact value of any food to the consumer. In science the figures that are given for the digestibility of the various foods refer to the completeness or extent to which the food is dissolved and transferred to the circulation, and an indigestible one is that of which a considerable portion passes out of the system into the feces without being disintegrated and absorbed.

Animal food is more completely digested than vegetable food, as shown by the difference of nitrogen in the feces. In meats 97 per cent. of the protein and 98 per cent. of the fat are absorbed. Lean meat is more rapidly digested than fat, and the flesh of young animals than that of older ones.

The breast of chicken, fresh beef, and mutton are among the most digestible of the solid foods. Raw and rare meats are more easily digested than well-done meats; in other words, cooking lessens the digestibility of meats. Steak should be broiled and never fried; all fried foods are difficult to digest. Veal and pork are both difficult to digest.

Eggs are almost as nutritious as meat; their digestibility is unsurpassed and only equalled by a few foods, such as milk and oysters. They are most easily digested when soft boiled or poached. Dry toast finely broken up and mixed with a soft-boiled egg aids in its digestion. Soft-boiled eggs are more easily digested than raw eggs, but the latter are less irritating to the stomach, probably because they are digested in the intestines. It has been found that two poached or soft-boiled eggs leave the stomach in from two to three hours; that is, in the same time as milk, oysters, white bread, and light fish.

Milk.—Although one of the most completely digested of foods in a mixed diet, milk is not quite so completely digested as meat and eggs. When milk is the sole food (milk diet) the proportion digested depends partly on the amount consumed. With the consumption of 3½ pints of milk daily the loss of milk solids varies from 10 to 11.16 per cent. Young children digest milk more completely than adults.