The skeleton of bone largely consists of a substance to which chemists give the name calcium phosphate, which, judging by its name, evidently contains calcium and phosphorus. Here, then, we can point to a very important function of these two elements. We may add one or two others. If you cut yourself so that blood comes to the surface of the skin, why does blood continue to flow only a little while and then stops altogether? (I am here ignoring very serious injury.) You will notice, if you have the courage to watch nature's operation closely enough, that the blood eventually forms a clot and so fills up the leak. This clotting or "coagulation" of the blood would be impossible but for the calcium present. To be sure, clotting is a process that involves more than the participation of calcium, but this element is necessary.

A number of very complicated substances - the phosphatids - are found in larger quantities in the brain than in other parts of the body. Though we do not know just what the phosphatids do, the mere fact that they are present points to a probable function; but the fact that they are in such abundance in brain tissue particularly, implies that a phase or phases of brain activity may be associated with their presence. The name phosphatid will possibly suggest to the reader that it is derived from the phosphorus it contains. Phosphatids do contain phosphorus, "Phosphorus for the Brain." Since phosphatids contain phosphorus, and since phosphatids are present in large amounts in the brain, it was somewhat natural to assume that by increasing the amount of phosphorus in the food, mental development might be influenced, possibly accelerated. All experiments in this direction have failed to confirm such an assumption. Nevertheless, the idea was sufficiently attractive to quacks and their advertising agents for them to seize upon it and create the slogan "phosphorus for the brain."

Phosphorus is essential; a certain minimum quantity must be present; but it does not necessarily follow that a surplus over the minimum can be used to advantage.

When we speak of phosphorus as being an es-tential in diet we do not mean the element in the free state. We never do mean the elements in the free state. Phosphorus is a poison. "Phosphorus poisoning" is quite common in match factories. But just as carbon is essential not in the form of coal, but in the form of some "food" containing it "in chemical combination," so phosphorus is utilized only when presented in "chemical combination" with other elements. Oxygen is the only element in the free state that is utilized by the body.

Iron is another essential constituent of the diet. It is needed to supply the iron present in hemoglobin, the red pigment of the blood. "Eat iron and you will be strong" - another one of those pieces of advice offered by quacks to credulous people. If you are anemic, iron in the form of one of its compounds, particularly such as are found in our foods, may be of some benefit; but far more important is to readjust your manner of living. A wholesome diet, plenty of sleep and plenty of fresh air, will do more to rebuild your red-blood cells than any of the iron tonics that have ever been invented.

A Comparison Of The Behavior In The Body Of Mineral Matter And The Organic Foodstuffs

A feature which sharply distinguishes the behavior of mineral matter from that of fat, carbohydrate and protein, is that the former undergoes no change prior to absorption by the blood. Your salt, for example, passes from the mouth to the stomach, and then into the intestine, and is there absorbed through the walls of the intestine, finding its way directly into the blood stream - the blood in turn carrying the salt to the various tissues of the body. The fat, protein and carbohydrate, however, undergo extensive alterations before the blood gets hold of them. The process of digestion is the process of converting the fats, proteins and carbohydrates into such a state as to make them fit for absorption by the blood. When you suffer from indigestion, that usually means that the workmen in the digestive tract - known as "enzymes" - responsible for the preparation of the foods in a form capable of assimilation by the blood, are either sick in bed, or too tired because of twelve-hour shifts (due to excessive eating), or are out on strike because of low wages (perhaps due to underfeeding).