In examining the foods adopted by different nations and classes of people, we find that many choose instinctively the kind best adapted to their individual needs. The climate, occupation, and water influence their choice.

Climate

Animal food is better for cold than for hot climates. We breathe more rapidly, take in more oxygen in cold weather, and the internal fire burns up more of the food. We exercise more, and this causes more rapid wearing out of muscle and flesh. Fat meat is not digested easily unless exercise be taken freely; more oxygen must be mixed with it to produce heat than is required for sugar and starch. In summer, when we exercise less, the waste is less, and we need less warmth giving food. The starch and sugar obtained from fruits and vegetables are easily digested, and furnish sufficient warmth. The Esquimaux or Greenlander consumes a large quantity of fat, or blubber oil, the most condensed form of carbonaceous food. This gives him the amount of heat necessary in an extremely cold climate. With this blubber he mixes some indigestible substances to give the needed bulk for the perfect action of the stomach. The people of Norway, Sweden, and Russia use large quantities of oily fish. In China, India, and other extremely hot climates, rice is the universal food. Rice contains a very small amount of flesh-forming material, being mostly starch, which is changed into sugar by the action of the saliva. The natives of rice-eating countries owe much of their lack of spirit and energy to this defective diet. But when eaten with butter or olive oil, and made into curries, pilaf, and pilau, with a small amount of flesh or fish, it supplies all the elements necessary for life in such climates. The Spaniard in his olla podrida - a stew of peas, bacon, or fowl, with red pepper - finds all the necessary elements. The red pepper, used so largely in the curries and other dishes common to hot climates, stimulates the liver, which is naturally weakened by the long-continued heat, and thus assists digestion. The Arab chooses dates, parched grains, mare's or camel's milk. The Turk adds to these melons and cucumbers. As we come northward again, we find more flesh-forming material in the polenta (a dish made of Indian corn) and the chestnuts, macaroni, and cheese used by the Italians. The pot-au-feu is the principal dish of every peasant in France. This furnishes the cheapest form of nutriment, and contains all the necessary elements of food.

The waters of a country sometimes determine the national food. In Ireland, where the waters are strongly impregnated with lime, they furnish what the potato, which is richer in potash and soda, lacks. When potatoes are combined with cabbage and pork, as in kolcannon, the flesh-forming element is supplied; and this, on account of the cost of meat, the laboring classes are unable to obtain in any other form. In England and Scotland, where the waters are soft, oats and wheat, which are rich in phosphates, are the staple diet. When combined with milk, eggs, rice, peas, beans, bacon, and cheese, their food is complete.

To satisfy the natural instinct to obtain these five elements, we all prefer our bread with butter or cream, our meat with potatoes, our rice with butter, milk, or eggs; our fish we cook in fat; we eat liver with bacon and ham, or bacon with eggs; we eat cheese with crackers, butter with cauliflower or cabbage, salt with all vegetables, oil with salad, and fresh vegetables with salt meat. Fruits and foods intended to be eaten raw contain a large proportion of water. This is supplied, when lessened by evaporation, by cooking and soaking in water. In cooking meats, we endeavor to retain all the juices, which are largely water. In spring we crave fresh green vegetables and salads, that we may have the potash salts of which there has been a deficiency in the winter diet.

Occupation affects our choice of diet. Persons engaged in sedentary occupations cannot digest as much nor as easily as those who labor out of doors. They should have food that gives the greatest amount of nourishment in the smallest compass, and it should be served in the most digestible form. Those who tax their brains severely should have animal food and the most digestible forms of starchy and warmth-giving foods. Those who exercise freely in the open air may take a larger quantity, and it need not be the most digestible, as they require food that will stay by them. The laborer instinctively prefers potatoes underdone, or "with a bone in them;" and he chooses salt meat, not only because it is cheaper, but because it stands by him longer. The salt causes him to drink water freely, and this supplies the waste caused by excessive perspiration. A diet of vegetables, peas, beans, cheese, oatmeal, bacon, and the cheaper, more indigestible parts of meat properly cooked, is suitable for laboring people.