Science News

Vitamin death-link hard pill to swallow

Vitamin supplements might make you die sooner, say researchers.

Goran Bjelakovic and his colleagues, from the University of Copenhagen, looked at the results from 230,000 people who had taken part in 67 previously published placebo-controlled trials of anti-oxidant vitamins and their effects on health and disease. 

Combining the data together in this way can make a study much more powerful because bias and error can be reduced, and subtle, possibly previously-invisible trends are easier to spot.

What emerged from this analysis, which included both healthy volunteers and patients with a range of diseases, was that taking anti-oxidants such as vitamin A or vitamin E are not linked to a lower death rate.  In fact, when the researchers focused on the results of the 46 trials with the least risk of bias, a worrying statistic emerged.  There was a 16% higher death rate amongst the users of vitamin A, patients given beta-carotene had a roughly 7% higher mortality rate, and those on vitamin E had a 4% rise in mortality.  Vitamin C and selenium didn't seem to increase nor decrease mortality rates, but the team stress that more data is needed to form firm conclusions about these agents.

The use of vitamin supplements, and anti-oxidants in particular, is based on sound science, since researchers think that most of the effects of ageing and diseases linked to it like heart disease are caused by damage done to cells by reactive chemicals called free radicals.  Antioxidants are thought shield cells from the damaging effects of free radicals, and therefore taking them as supplements might help to fend off disease and the effects of the ageing process.

Whilst that may be true, what this study shows is that obtaining anti-oxidants from a packet is not beneficial to your health and may even paradoxically increase mortality.  Instead the only proven way to cut cancer and heart disease deaths is to eat five or more portions of fruit and veg daily, which has consistently emerged in trials as the best predictor of living to a ripe old age.

20th Apr 2008