Vitamin D and your health: Breaking old rules, raising new hopes
Vitamin D was discovered in 1920, culminating the long search for a way to cure rickets, a painful childhood bone disease. Within a decade, the fortification of foods with vitamin D was under way, and rickets became rare in the United States. But solving the problem of rickets was only the beginning of research into vitamin D. Results suggest that vitamin D may have an important role in many aspects of human health, from bone fractures to prostate cancer, cardiovascular disease, neuromuscular problems, and diabetes.
Breaking the old rules
Vitamin D is one of the 13 vitamins discovered in the early 20th century by doctors studying nutritional deficiency diseases. Ever since, scientists have defined vitamins as organic (carbon-containing) chemicals that must be obtained from dietary sources because they are not produced by the body's tissues. Vitamins play a crucial role in our body's metabolism, but only tiny amounts are needed to fill that role.
Although vitamin D is firmly enshrined as one of the four fat-soluble vitamins, it is not technically a vitamin. True, it's essential for health, and only minuscule amounts are required. But it breaks the other rules for vitamins because it's produced in the human body, it's absent from all natural foods except fish and egg yolks, and even when it's obtained from foods, it must be transformed by the body before it can do any good.