Millions of people taking vitamin supplements will today be urged to exercise caution by the Department of Health over fears that in some cases they may do more harm than good.
“Most people are able to meet their nutritional needs by eating a balanced, varied diet including plenty of fruit and vegetables, and therefore do not need to take dietary supplements,” a spokesperson said last night.
The advice, following a large review of scientific evidence first published last year and reported in The Times, comes as scientists appeal for greater regulation of vitamin supplements.
“There is a need to exercise caution in the use of high doses of purified supplements of vitamins, including antioxidant vitamins, and minerals, as their impact on long term health may not have been fully established and they cannot be assumed to be without risk,” she said.
“Anyone concerned about their diet should speak to their doctor or dietitian.”
The review of 67 studies involving more than 230,000 people is republished today by the Cochrane Collaboration, an international organisation for evidence-based research. The review found no evidence that the nutrition supplements extend life. On the contrary, vitamins A and E and beta carotene appear to slightly increase premature death rates among those taking them. Vitamin C and selenium have no effect.
When the different antioxidants were assessed separately, trials with a low risk of bias were included and selenium excluded, vitamin A was linked to a 16 per cent increased risk of dying prematurely, beta-carotene to a 7 per cent increased risk and vitamin E to a 4 per cent increased risk. However, there was no significant detrimental effect caused by vitamin C.
“We found no evidence to support antioxidant supplements for primary or secondary prevention,” the authors said. “Beta-carotene, vitamin A and vitamin E given singly or combined with other antioxidant supplements significantly increase mortality.
“There is no evidence that vitamin C may increase longevity. We lack evidence to refute a potential negative effect of vitamin C on survival. Selenium tended to reduce mortality but only when high-bias risk trials were considered. Accordingly, we need more research on vitamin C and selenium.”
The reviewers now say that they want more regulation of the health supplements industry and make a plea for urgent political action.
Pamela Mason, nutritionist and spokeswoman for the Health Supplements Information Service, which is funded by a grant from the Proprietary Association of Great Britain, said: “Antioxidant vitamins, including these noted in this Cochrane review, are essential for health.
“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 that we don’t already know.”
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