Vitamin supplements taken by millions of people in the hope of extending their lives may actually increase the risk of premature death in some cases, Danish researchers said today.
Scientists reviewed 67 studies on 230,000 people to see whether so-called antioxidant vitamins prolonged life expectancy.
They found that vitamin C, often taken in an attempt to ward off colds, seemed to have no positive or negative effects. Vitamins A and E, traditionally used to help strengthen bones and improve circulation, showed if anything, increased rates of mortality, as did beta-carotenes, which are taken for healthy vision.
"The bottom line is that current evidence does not support the use of antioxidant supplements in the general healthy population or in patients with certain diseases," said Goran Bjelakovic, who carried out the review at Copenhagen University Hospital in Denmark.
"We could find no evidence to support taking antioxidant supplements to reduce the risk of dying earlier in healthy people or patients with various diseases."
He added: "The findings of our review show that if anything, people in trial groups given the antioxidants beta-carotene, vitamin A, and vitamin E showed increased rates of mortality."
Antioxidants are promoted as helping to protect the body from free-radicals, highly reactive molecules capable of causing damage in the brain and other tissues. As well as vitamins A, C and E, they include zinc, ginkgo biloba, grape seed extract and green tea extract.
Some in the vitamins industry criticised the selection of studies reviewed, saying they focused on reducing mortality rather than advantages which are listed in other studies.
The industry-backed Health Supplements Information Service said the review showed inconsistent findings and demonstrated "nothing new whatsoever". It said antioxidant supplements are essential for those people who have poor intakes of nutrients.