166. Phosphorus And Brain Power

It was at one time popularly taught that phosphorus has a special relation to brain activity and because fish was supposed to contain much phosphorus it was commonly spoken of as "brain food." As a matter of fact, it has never been shown that this element has an especial relation to brain activity, and, moreover, fish is no richer in phosphorus than many other foods, such as meats, milk, cheese, and certain grains (see p. 387). To be sure, the nerve tissue is relatively rich in phosphorus, but other elements are just as essential to the structure of the brain..

157. Foods Supplying Mineral Compounds

Nature seems to have adapted our needs to the compounds furnished by the natural food products, such as the cereal grains, milk, meat, and other unmodified materials, as they supply a complete variety of the needed inorganic substances. Milk, which is the exclusive food of infants, is especially adapted to rapid bone formation. It is only when modified (artificial) foods are largely eaten, foods from which the mineral salts have been extracted by manufacturing processes, that we need fear a deficiency of the necessary mineral compounds. (See pp. 210-211.)

Much is written about the proper proportion of protein and carbohydrate in the food, but it is to be feared that the equally critical matter of the supply of the so-called mineral ingredients does not receive attention commensurate with its importance.

168. Functions Of Protein

While there are at present many unsolved problems relative to the nutritive offices of protein, there is no reasonable doubt that the food proteins are the only source of similar substances in the animal body. This is equivalent to a statement that from the food proteins are formed the muscles, the connective tissues, the skin, hair, and the major part of the tissues of the secretive and excretive organs; in short, that they are the source of a large proportion of all the working parts of the human body. So far, scientific research has not succeeded in demonstrating that a protein is ever synthesized (built up from simple compounds) outside of the plant. It appears that bodies of this class must come to animal life fully elaborated, for when protein is absent from the food, the body protein is utilized to maintain the vital functions, even if nitrogen compounds of a lower order are present. This is a truth of great significance in its relation to the nutrition of man. The nitrogenous tissues are those that largely determine the vigor and quality of any individual, and as these are formed rapidly in the early stages of growth, a normal and unrestricted development demands an adequate supply of protein food.

The proteins are a source to the body of two important ash constituents, viz., phosphorus and sulfur. There are reasons for believing that these two elements enter into the building of the protein tissues only when they are supplied in the food in their protein combinations. It does not seem to be definitely proven that their inorganic salts may be used by the animal organism for synthesizing phosphorus and sulfur-bearing proteins.