Throughout the history of mankind from primitive man to the present time, vitamin deficiencies have been a major cause of death and disease. Pellagra, scurvy and beri-beri have decimated armies, ships' crews and even nations (Figure I). As late as 1925 the disease 'pernicious' anaemia caused by the absence of vitamin Bl2 within a person's body really lived up to its name. Although there were isolated instances of recognition of dietary deficien­ cies even a thousand years ago, the importance of dietary factors in the gene­ sis of these diseases was more widely recognized from the eighteenth century onwards and it was not until this century that the chemical structure of these factors was determined and the substances themselves synthesized. As the science of biochemistry has developed it has been found that the clinical manifestations of vitamin deficiency follow derangement of multiple metabolic functions. The majority of the vitamins in fact form specific co-en­ zymes in various chemical processes but at least one is converted within the body into a hormone. The commercial extraction and synthesis of the vitamins, which began mainly in the 1930S and 1940s, produced adequate quantities for a relief of vitamin deficiency diseases. The use of vitamins then became fashionable and dramatic cures were claimed for an ever increasing number of diseases.