( Originally Published 1936 )
RICKETS DISEASE OF INFANCY IS PREVENTED BY SUNLIGHT
THERE is enough calcium, or lime, in the body to whitewash a pretty good sized building. It is a necessary ingredient, being found in the bones, teeth and blood. The muscles demand a certain amount of calcium in the blood for their proper action. Calcium is found in the milk of all animals, being especially necessary to growing animals on account of the requirement in developing bones and teeth.
Even if calcium is present in the diet, however, it will not necessarily be utilized by the body. Various factors seem to influence this utilization. One of them, undoubtedly, is the presence of sunlight. Sunlight does this probably through the development in the body of the substance known as vitamin D, which is present in cod liver oil and the liver of many animals; also artificially in the substance known as Viosterol.
Vitamin D is formed in the skin by the action of sunlight, and is stored in the liver.
Rickets is the most common disease due to improper utilization of calcium in the body. It results in stunted growth and deformities of the bones. Rickets is a disease exclusively of young children. In order to prevent rickets the baby must, therefore, be exposed to sunlight regularly and daily.
The relationship between the amount of rickets and the lack of sunshine in any population is remarkably close. For instance, rickets is far commoner in negro children than in white because the sunlight does not get a chance to penetrate through the darker skin. Even in countries where there is a great deal of sunshine, such as Algeria, rickets is prevalent because certain religious customs keep women and children indoors, away from sunlight. Purdah, for instance, is a religious custom in India, as in Africa, which keeps women indoors in the early stages after childbirth, and hence rickets is present in three out of every four children in these communities.
Another disease of infancy, called "tetany," in which there are spasms in the muscles, has been greatly improved and brilliant results have been obtained by exposing the patient to light.
The expectant mother, and the mother during the period when she is nursing the baby, require an extra amount of calcium in their bodies because of the drain of calcium in the milk and to form the baby's bones. It has been found that when mothers receive ultra-violet light exposures, the calcium content of the blood remained normal or showed an actual increase.
In fractures and injuries there is -theoretically a need for more calcium in order to help the bones to heal. Sunlight or ultraviolet light exposures in these conditions have not, however, been as successful as theory would suggest.