A handbook of invalid cooking

by Mary A. Boland

To summarize: The digestion and absorption of nitrogenous compounds take place in both the stomach and the intestines.

NUTRITION

One of the important points to bring to the notice of pupils in the study of cookery is the phenomenon of nutrition. It is astonishing how vague are the ideas that many people have of why they eat food, and vaguer still are their notions of the necessity of air, pure and plenty. Once instruct the mind that it is the air we breathe and the food we eat which nourish the body, giving material for its various processes, for nervous and muscular energy, and for maintaining the constant temperature which the body must always possess in order to be in a state of health, and there is much more likelihood that the dignity and importance of proper cooking and proper food will not be overlooked.

A knowledge that the health and strength of a person depend largely upon what passes through his mouth, that even the turn of his thinking is modified by what he eats, should lead all intelligent women to make food a conscientious subject of study.

In general, by the term "nutrition" is meant the building up and maintaining of the physical framework of the body with all its various functions, and ultimately the mental and moral faculties which are dependent upon it, by means of nutriment or food.

The word is derived from the Latin nutrire, to nourish. The word "nurse" is from the same root, and in its original sense means one who nourishes, a person who supplies food, tends, or brings up.

Anything which aids in sustaining the body is food; therefore, air and water, the two most immediate necessities of life, may be, and often are, so classed.

Nutriment exclusive of air is received into the body by means of the alimentary canal. The great receiver of air is the lungs, but it also penetrates the body through the pores of the skin, and at these points carbonic acid is given off as in the lungs. The body is often compared to a steam-engine, which takes in raw material in the form of fuel and converts it into force or power. Food, drink, and air are the fuel of the body,—the things consumed; heat, muscular and intellectual energy, and other forms of power are the products.

Food, during the various digestive processes, becomes reduced to a liquid, and is then absorbed and conveyed, by different channels constructed for the purpose, into the blood, which contains, after being acted upon by the oxygen of the air in the lungs, all those substances which are required to maintain the various tissues, secretions, and, in fact, the life of the system.

Some of the ways in which the different kinds of food nourish the body have been found out by chemists and physiologists from actual experiments on living animals, such as rabbits, dogs, pigs, sheep, goats, and horses, and also on man. Often a scientist becomes so enthusiastic in his search for knowledge about a certain food that he gives his own body for trial. Much valuable work has been done in this direction during the last decade by Voit, Pettenkofer, Moleschott, Ranke, Payen, and in this country by Atwater.