Claims | Health effects from very high doses of vitamins. |
---|---|
Related scientific disciplines | vitamins, dietary supplements |
Year proposed | 1930s |
Notable proponents | Fred R. Klenner, Linus Pauling |
Pseudoscientific concepts |
Megavitamin therapy is the use of large doses of vitamins, often many times greater than the recommended dietary allowance (RDA) in the attempt to prevent or treat diseases. Megavitamin therapy is typically used in alternative medicine by practitioners who call their approach "orthomolecular medicine", but also used in mainstream medicine for "exceedingly rare" genetic conditions that respond to megadoses of vitamins.
Nutrients may be useful in preventing and treating some illnesses, but the conclusions of medical research are that the broad claims of disease treatment by advocates of megavitamin therapy are unsubstantiated by the available evidence. It is generally accepted that doses of any vitamin greatly in excess of nutritional requirements, will result either in toxicity or in the excess simply being metabolised - evidence in favour of vitamin supplementation supports only doses in the normal range. Critics have described some aspects of orthomolecular medicine as food faddism or even quackery. Research on nutrient supplementation in general suggests that some nutritional supplements might be beneficial, and that others might be harmful; several specific nutritional therapies are associated with an increased likelihood of the condition they are meant to prevent.
Megavitamin therapy must be distinguished from the usual 'vitamin supplementation' approach of traditional multivitamin pills. Megavitamin doses are far higher than the levels of vitamins ordinarily available through western diets. Multivitamin supplementation has been demonstrated to have negligible effect in treating cancer.
A study of 161,000 individuals (post-menopausal women) provided, in the words of the authors, "convincing evidence that multivitamin use has little or no influence on the risk of common cancers, cardiovascular disease, or total mortality in postmenopausal women".
In the 1930s and 1940s, some scientific and clinical evidence suggested that there might be beneficial uses of vitamins C, E, and B3 in large doses. Beginning in the 1930s, the Shutes in Canada developed a megadose vitamin E therapy for cardiovascular and circulatory complaints, naming it the "Shute protocol".