Food is anything which nourishes the body. Thirteen elements enter into the composition of the body: oxygen, 62 1/2%; carbon, 21 1/2%; hydrogen, 10%; nitrogen, 3%; calcium, phosphorus, potassium, sulphur, chlorine, sodium, magnesium, iron, and fluorine the remaining 3%. Others are found occasionally, but, as their uses are unknown, will not be considered. Food is necessary for growth, repair, and energy; therefore the elements composing the body must be found in the food. The thirteen elements named are formed into chemical compounds by the vegetable and animal kingdoms to support the highest order of being, man. All food must undergo chemical change after being taken into the body, before it can be utilized by the body; this is the office of the digestive system. Food is classified as follows:—
The chief office of proteids is to build and repair tissues. They can furnish energy, but at greater cost than carbohydrates, fats, and oils. They contain nitrogen, carbon, oxygen, hydrogen, and sulphur or phosphorus, and include all forms of animal foods (excepting fats and glycogen) and some vegetable foods. Examples: milk, cheese, eggs, meat, fish, cereals, peas, beans, and lentils. The principal constituent of proteid food is albumen. Albumen as found in food takes different names, but has the same chemical composition; as, albumen in eggs, fibrin in meat, casein in milk and cheese, vegetable casein or legumen in peas, beans, and lentils; and gluten in wheat. To this same class belongs gelatine. The chief office of the carbohydrates is to furnish energy and maintain heat. They contain carbon, hydrogen, and oxygen, and include foods containing starch and sugar. Examples: vegetables, fruits, cereals, sugars, and gums. The chief office of fats and oils is to store energy and heat to be used as needed, and constitute the adipose tissues of the body. Examples: butter, cream, fat of meat, fish, cereals, nuts, and the berry of the olive-tree. The chief office of mineral matter is to furnish the necessary salts which are found in all animal and vegetable foods. Examples: sodium chloride (common salt); carbonates, sulphates and phosphates of sodium, potassium, and magnesium; besides calcium phosphates and iron. Water constitutes about two-thirds the weight of the body, and is in all tissues and fluids; therefore its abundant use is necessary. One of the greatest errors in diet is neglect to take enough water; while it is found in all animal and vegetable food, the amount is insufficient.
Age, sex, occupation, climate, and season must determine the diet of a person in normal condition Liquid food (milk or milk in preparation with the various prepared foods on the market) should constitute the diet of a child for the first eighteen months. After the teeth appear, by which time ferments have been developed for the digestion of starchy foods, entire wheat bread, baked potatoes, cereals, meat broths, and occasionally boiled eggs may be given. If mothers would use Dr. Johnson's Educators in place of the various sweet crackers, children would be as well pleased and better nourished; with a glass of milk they form a supper suited to the needs of little ones, and experience has shown children seldom tire of them. The diet should be gradually increased by the addition of cooked fruits, vegetables, and simple desserts; the third or fourth year fish and meat may be introduced, if given sparingly. Always avoid salted meats, coarse vegetables (beets, carrots, and turnips), cheese, fried food, pastry, rich desserts, confections, condiments, tea, coffee, and iced water. For school children the diet should be varied and abundant, constantly bearing in mind that this is a period of great mental and physical growth. Where children have broken down, supposedly from over-work, the cause has often been traced to impoverished diet. It must not be forgotten that digestive processes go on so rapidly that the stomach is soon emptied. Thanks to the institutor of the school luncheon-counter! The daily average ration of an adult requires
About one-third of the water is taken in our food, the remainder as a beverage. To keep in health and do the best mental and physical work, authorities agree that a mixed diet is suited for temperate climates, although sound arguments appear from the vegetarian. Women, even though they do the same amount of work as men, as a rule require less food. Brain workers should take their proteid in a form easily digested. In consideration of this fact, fish and eggs form desirable substitutes for meat. The working man needs quantity as well as quality, that the stomach may have something to act upon. Corned beef, cabbage, brown-bread, and pastry will not overtax his digestion. In old age the digestive organs lessen in activity, and diet should be almost as simple as that of a child, increasing the amount of carbohydrates and decreasing the amount of proteids and fat.