The history of the discovery of the B vitamins includes both the recognition that particular diseases can result from dietary inadequacies and the subsequent isolation of specific nutrients from foods that have been found to prevent and to cure those diseases. Most of these dietary deficiencies were first recognized in humans, but in certain instances, the deficiency was produced by feeding restricted diets to experimental animals.

After each of the B vitamins was isolated, extensive biochemical and physiological studies were conducted to define their specific functions. States of B vitamin dependency were also discovered in which the need for a particular vitamin exceeded the physiological level. These vitamin dependencies were found either to have a genetic basis or to be drug-induced.

Moreover, recognition that certain synthetic compounds bearing close chemical resemblance to B vitamins could block the activity of naturally occurring vitamins has led to a better understanding of vitaminic functions and has provided us with certain drugs that are used in cancer chemotherapy and in the treatment of infections and inflammatory diseases.

Vitamin B research, as well as clinical and public health information, is summarized here to emphasize some significant advances in our knowledge of these compounds. But first a note on nomenclature seems appropriate.