“If it ain?t broke don?t fix it” is perhaps the best policy in the light of increasing scientific evidence that over doing it with vitamin supplements can result in serious harm.
The controversy was fired up by the publication of a Finnish lung cancer study in 1994 which suggested that giving Vitamin A to smokers actually increased the risk of lung cancer. Further concern was raised about overdosing on Vitamin A supplements by a study in China on the incidence of Gastric cancer.
The results of a number of studies on Vitamins and cancer have been inconsistent. However what seems to be a predictable pattern is that low vitamin intake causes disease and very high vitamin intake is associated with different but similarly serious medical problems. It has been disturbing for example to discover that Vitamin E supplements given in one study to reduce cardiovascular disease actually increased mortality from a stroke in that study.
Until we know more about these controversial issues it would seem sensible not to indulge in habitual and continual intake of supplements.