THERE is no evidence that taking antioxidants such as vitamins A and E prolongs life, and some may actually be harmful, research suggests today.
A review of 67 studies involving more than 230,000 people found "no convincing evidence" antioxidant supplements cut the risk of dying.
"Even more, beta-carotene, vitamin A, and vitamin E seem to increase mortality," the experts write.
The review, published by The Cochrane Collaboration, involved trials on beta-carotene, vitamin A, vitamin C, vitamin E and selenium.
The experts noted that the studies involved varying doses of each antioxidant, with
beta-carotene ranging from 1.2mg to 50mg daily and vitamin C from 60mg to 2,000mg daily. Subjects were either healthy and taking part in primary prevention trials or had some disease and were taking part in secondary prevention trials.
A total of 232,550 people were included across all the trials, while 47 trials included 180,938 people and had a low risk of bias. In these trials, supplements "significantly increased mortality", the authors write.
When the antioxidants were assessed separately and trials at low risk of bias were included and selenium excluded, vitamin A was linked to a 16 per cent increased risk of dying, beta-carotene to a 7 per cent increased risk and vitamin E to a 4 per cent increased risk. However, vitamin C caused no significant detrimental effect, the authors say.
"We found no evidence to support antioxidant supplements for primary or secondary prevention," they add. "Beta-carotene, vitamin A and vitamin E significantly increase mortality."
Goran Bjelakovic, a visiting researcher who carried out the review at Copenhagen University Hospital in Denmark, added: "We could find no evidence to support taking antioxidant supplements to reduce the risk of dying earlier.
" If anything, people given the antioxidants beta-carotene, vitamin A, and vitamin E showed increased rates of mortality."
"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."
But Patrick Holford, a nutritionist who has formulated some supplements for the firm Biocare, said the Cochrane review was a "stitch-up".
He added: "Antioxidants are not meant to be magic bullets and should not be expected to undo a lifetime of unhealthy habits. But used properly, in combination with eating a healthy diet, getting plenty of exercise and not smoking, antioxidant supplements can play an important role in maintaining and promoting overall health."
Pamela Mason, nutritionist and spokeswoman for the Health Supplements Information Service, said: "Antioxidant vitamins are essential for health and dietary surveys have shown that some people have poor intakes of such nutrients.
"Trials using antioxidant supplements have shown inconsistent findings and yet another review or meta-analysis is not going to tell us anything at this stage we don't already know.
"What we need now, I am afraid, is yet further research."
The A to E of health
SUPPLEMENTS like vitamin A and E, which are also found naturally in food, are taken by many to improve health.
Vitamin A helps to maintain the health of skin and mucus linings in the nose and to strengthen immunity from infections.
It can also help vision in dim light. Good sources of vitamin A include cheese, eggs and oily fish.
Vitamin E also has a number of important functions. It helps to protect cell membranes by acting as an antioxidant.
It is found in foods such as soya, corn and olive oil.