( Originally Published 1938 ) In addition to the elements
derived from the proteins, carbohydrates and fats, the body is
composed of mineral elements. The bones, for example, are made
up of calcium and phosphorus. The brain, too, has a large amount
of phosphorus. The blood contains iron and copper and the
thyroid gland, iodine. All the tissues contain common salt which
is known scientifically as sodium chloride. Just like the other
elements, these are constantly being broken down and excreted.
Naturally they must be replaced. Therefore our food must contain
them in appreciable amounts. This is imperative not only because
they are needed for the building of bone, brain, blood and other
tissue, but because they are necessary for other functions. They
influence the irritability of the muscles, that is their power
to react to stimuli. They also influence the acidity or
alkalinity of the digestive juices, and maintain the neutrality
of the body tissues the acid alkali balance to which we alluded
when discussing th