The purposes of food are to promote growth, to supply force and heat, and to furnish material to repair the waste which is constantly taking place in the body. Every breath, every thought, every motion, wears out some portion of the delicate and wonderful house in which we live. The various vital processes remove these worn and useless particles; and in order to keep the body in health, their loss must be made good by constantly renewed supplies of material properly adapted to replenish the worn and impaired tissues. This renovating material must be supplied through food and drink, and the best food is that by which the desired end may be most readily and perfectly attained.

The great diversity in the character of the several tissues of the body makes it necessary that food should contain a variety of elements in order that each part may be properly nourished and replenished. The nutritive elements found in foods are albuminous compounds, starch, sugar, fats, and mineral substances. Besides these, most foods contain water and more or less indigestible material.

The nutritive food elements are for convenience classified according to their chemical composition into three groups: nitrogenous elements, which include albumin, gluten, casein, and allied substances; carbonaceous elements, including starch, sugar, and fats , and inorganic, or mineral, elements.

Each of these different groups of elements has a particular work to perform in the maintenance of health, so it is especially necessary that our food should contain some of each kind of elements. It is likewise essential that these elements, particularly the nitrogenous and carbonaceous, should be supplied to the system in certain definite proportions, as the body is able to appropriate only a certain amount of each. More of the carbonaceous than of the nitrogenous elements are needed. One part nitrogenous material to every eight or ten parts carbonaceous, is, according to the latest authorities, a good proportion.

Of the different nutritive elements, the nitrogenous is physiologically the most important, as these elements especially nourish the brain, nerves, muscles, and all the more highly vitalized and active tissues of the body, and also serve as a stimulus to tissue change. Hence it may be said that a food deficient in these elements is a particularly poor food. The carbonaceous elements furnish material for the production of heat and energy when used in connection with other food elements.

The mineral elements aid in furnishing the requisite building material for bones and nerves. Most food substances are deficient in one or another of the food elements, and need to be supplemented by other foods containing the deficient element in superabundance, since to employ a dietary in which any one of the nu-tritive elements is lacking, although in bulk it may be all the digestive organs can manage, is really starvation, and will in time occasion serious results.

It will thus be apparent that great care should be exercised in the selection and combination of food materials. A careful study of the nutritive values of various foods is a matter of first importance in the selection of food for the daily needs of the household. The accompanying table of food analyses will serve as an aid to the housekeeper in this direction.

Table Showing The Nutritive Values Of Some Common Food Substances

A knowledge of the digestibility and proper preparation of foods is likewise essential, since the fitness of a food to be good, material for body building depends upon its digestibility, its palatability, and its adaptability to the needs of the user, as well as upon its nutritive value.1

Simplicity of diet should also be a point of first consideration, since the simplest foods, as a rule, are the most healthful. Variety is needed; but the tendency is to supply our tables with too many kinds, and to prepare each dish in the most elaborate manner, until in many households the cooking of the food has come to be almost the chief end of life. While the diet of the family should be looked upon as of sufficient importance to demand careful consideration, its preparation should not usurp the larger share of one's time.

A great variety of foods at one meal creates a love of eating as a source of pleasure merely, and likewise furnishes temptation to overeat. Let us have well-cooked, nutritious, palatable food, and plenty of it, with a suitable variety from day to day, but not too great a variety at each meal.

1 In the author's larger work, "Science in the Kitchen," are given chapters on the digestion of foods and the principles underlying their proper selection and preparation, together with complete tables, showing the nutritive value of foods.