Vitamin supplements do nothing to stave off illness and could even lead to cancer, a leading expert has warned.
Professor Martin Wiseman, medical and scientific adviser for the World Cancer Research Fund, has pointed out that people who regularly take vitamin and mineral supplements instead of eating a balanced diet are at greater risk.
"Many people think they can reduce their cancer risk by taking supplements, but the evidence does not support this," the Daily Express quoted Wiseman as saying.
"Just because a dietary pattern that provides a relatively high level of a particular nutrient might protect against cancer, it does not mean that taking it in tablet form will have the same effect.
"In fact, at high doses the effect of these micronutrients is unpredictable and can be harmful to health," Wiseman added.
Research suggests that vitamins A and E can actually cause illness.
Speaking about the effect of vitamin overdose, Wiseman said: "Some people may be doing themselves more harm than good.
"There are studies that show high doses of some supplements can increase risk of some cancers.
"There is convincing evidence that taking beta-carotene supplements actually increases the risk of lung cancer in current smokers.
"The evidence about the difficulty in predicting the effect of high-dose supplements is getting stronger all the time.
"For example, in 2007 we concluded that taking selenium supplements probably reduces risk of prostate cancer."
"But a recent study unexpectedly found no evidence that it reduces risk, so my personal interpretation would be that the jury is still out on this," Wiseman added.