Milk is the sole nourishment provided by nature for the young of man and beast, and contains all food stuffs in the best proportions for the infant’s needs. But milk alone is not adapted to the adult. Supplemented by other food, however, it is invaluable and not appreciated as it ought to be. Cheese is highly nutritious, but not very digestible. Eggs resemble milk in composition, except that they contain less water. The nearer raw the more digestible they are, and the yolk is more so than the white, which, when hard boiled, is the most indigestible form of albumen known. The addition of eggs to baked puddings is of questionable utility, and next to a raw egg, well beaten, in milk or water or in soup or beef tea, not too hot, a light boiled custard is the best form for invalids.
From the earliest ages the grains or cereals have formed a portion of man’s diet. Wheat has always been the most esteemed, and some varieties of it may be grown in every climate except the very hottest and coldest. Barley, rye and oats may be grown much farther north, but are less digestible. Oatmeal cannot be made into bread, rye bread is rapidly being displaced by wheat, and barley has almost entirely fallen into disuse, except for the purposes of the brewer and distiller. In the tropics rice is the chief cereal. It consists almost entirely of starch, and is thus unfit for bread making. Our own corn, which we inherit from the Indians and have immensely improved, is of all the cereals the nearest approach to a perfect food.
Among roots the potato holds the most prominent place. Potatoes are wholesome only when the starch granules, which compose them, are healthy, as shown by their swelling out during boiling, bursting their covering, and converting themselves into a floury mass, easily broken up. They contain from twenty to twenty-five per cent of nutriment, but this is almost entirely starch, and as a food in combination with meat, cheese or other vegetables, they are not equal to rice. Parsnips, beets and carrots are wholesome and nutritious, and should be used much more than they are. Turnips are not so valuable. Cabbages and their kindred have but little food value, although the salts they contain are excellent in the preservation of health. As regards green vegetables in general the importance of having them fresh is not sufficiently realized. When they have been cut some days changes occur just as truly as in animal food, and the freshness should be carefully watched, except with those specially adapted for storing.
Salads are useful in maintaining the health, although many of them are very indigestible, those of radishes, celery and cucumbers among the list. Fruits are prized chiefly for their taste. Grapes alone, among fresh fruits, contain any large proportion of food stuff. As an aid to digestion, however, they all are properly highly prized. Fruits should be fully ripe, but without any trace of decomposition.
Stimulants and condiments of high seasoning have little food value of their own, but they have value as aids to digestion when used moderately, and in making simpler foods more palatable. Alcoholic liquors, whether mild or strong, hardly need to be considered here. It is to be gravely doubted if such beverages are ever necessary or of value in the diet, and in this place we are not considering them from any other point of view.
It is equally difficult to speak positively and generally in reference to tea and coffee. It is safe to say, however, that many people drink these tempting beverages to excess, with harm resulting to themselves from it. Tea and coffee alike act as exciters of the nerve centers, accelerating and strengthening the heart’s action and respiration, causing wakefulness, and increasing the secretion of the kidneys and skin. Tea and coffee are far superior to alcohol in enabling man to resist the depressing influence of fatigue and exposure to cold, and are admirably adapted to the needs of soldiers on the march or men on outdoor night duty. Cocoa, chocolate and their preparations contain some active elements similar to those of tea and coffee, but the proportion of nutritive material is so much greater that they are to be looked on rather as food than drink.
The considerable use of ice and iced drinks is to be avoided. Small quantities are of service in relieving thirst and vomiting, and in cooling the body when exposed to great heat. But since ice causes the mucous membrane of the stomach to become temporarily pale and bloodless, it checks or altogether suspends the flow of the gastric juice. Thus iced drinks at meals interfere seriously with digestion. Observe also that there is no truth in the popular notion that frozen water or ice is always pure. Water is not purified by freezing, and may be even more polluted than it was before.
CLOTHING AND ITS RELATION TO HEALTH
Having considered thus briefly the matter of food and its relation to health, the question of clothing and personal hygiene now rises for attention. Besides serving for covering and adornment and guarding the body from injury, the use of clothing is to help in preserving the proper animal heat in spite of external changes. In health the normal temperature of the body, ninety-eight to ninety-nine degrees Fahrenheit, is invariable. In order that this temperature shall be maintained with the least strain on the vitality, the clothing should be such that heat is not readily conducted to or from the body.
Cotton and linen keep off the direct rays of the sun and favor the loss of heat from the body, but being bad absorbers of moisture they are apt to interfere with evaporation from the skin, and cause dangerous chills. Linen and cotton are good conductors of heat, especially the former, and do not readily absorb moisture. Silk and wool are bad conductors. Wool has also a remarkable power of so completely absorbing moisture that it feels dry when cotton or linen would be wet and cold. Its value as a non-conductor, retaining internal heat and excluding external heat, is shown by the fact that we wrap ice in blankets to keep it from melting, and cover teapots with woolen “cosies” to keep them from getting cold. These qualities together render it the most perfect material for clothing under all conceivable circumstances.