Natural foods were originally simply nature-produced. By the aid of humankind cultivated and manufactured foods have become natural as foods in so far as they have become usual and humankind has become adjusted to their use. All modification of food to improve it as human food is to be encouraged, but is to be distinguished from changes in foods to increase profit rather than to improve their nourishing properties.

The tendency to-day in artificial changes in food is commercial rather than nutritive. Knowledge of food and its use to the human body should direct both the selection of food and the regulation of its production.

Some scientists claim that artificially prepared substances that are chemically the same as food-substances are satisfactory food-substitutes, and that they may be made even more free from substances undesirable in food than are natural foods. Others think not. But all are agreed that such is not yet the practice, and that science has as yet been used more in the service of profit than in purifying food. Constructed foods are now on the market; such are some fruit-flavors.

The use of by-products of manufacture for food has introduced cottonseed-oil, glucose, and other substances that chemically are the equivalent of foods long in use. When made of wholesome materials and by means of sanitary processes such foods are not objectionable, though they rarely are as palatable as are foods more directly produced by nature. They often are not so generally digestible.

Foods constructed to deceive, through a desire to save expense in order to increase profit, may be dangerous to health. Jams made of fruit-pulp discarded from jelly-making and colored artificially cannot be nutritious nor can catsup made of woody-fiber vegetables and colored red with aniline dyes.