We can get the vitamins we need from a healthy diet containing fruit and vegetables, yet an industry has grown up based on the tempting idea that using supplements to boost our intake will make us even healthier. But will it?

In Britain we spend roughly £400 million pounds a year on supplements, most bought by the middle-aged and elderly. We don’t know how many people use them here but it’s likely to be much the same as in the United States, where one in three people regularly take a vitamin supplement.

But does taking supplements bring any benefits? Over the past few decades there has been a lot of research to find out, comparing the health of those taking supplements with those who didn’t. Unfortunately, many of these studies have not been able to provide a clear answer. They had too few participants or did not go on for long enough, or inconsistencies allowed conflicting interpretations.

There have been some large-scale studies, though. For example, the Cancer Prevention Study in the early 1980s recruited 1 million people and the Women’s Health Initiative another 160,000. Neither showed any substantial benefits from supplements in reducing cardiovascular disease such as heart attacks or stroke. Another study – the Nurses Health Study involving 89,000 nurses over 5 years – indicated that supplements gave some protection from colon cancer. But, worryingly, a study in Sweden of 35,000 women found a 19% increase in breast cancer.

When researchers examined 68 studies involving 230,000 subjects together in a meta-analysis, they found no overall benefit from taking supplements, even though some of the individual studies had suggested there might be.

These somewhat mixed findings have made coherent advice difficult. An absolutely rigorous study has been needed, with enough participants unfailingly taking either the supplement under investigation or an inactive placebo for enough years.

Such a study has now been carried out. The Physicians’ Health Study II involved 14,600 male physicians with a mean age of 64 years, 70 per cent of whom continued for more than 10 years in a randomised controlled double blind trial. Two papers have been published so far*. The first showed no reduction in heart attacks or stroke, the other a modest but statistically significant reduction in cancer (from 18 per thousand person-years down to 17). More papers are likely to follow, covering eye disease and cognitive decline.

So at last there is clear evidence from a rigorously controlled trial that taking vitamin supplements can result in a significant (but modest) reduction in cancer in men. There’s no reason to suppose the findings wouldn’t also apply to women. But there’s an equally clear indication of no benefit in heart disease or stroke. So what advice should be given?

Some people may feel that the modest reduction in cancer warrants the trouble and expense of taking a vitamin supplement. On the other hand, it might be better simply to eat the recommended levels of fruit and vegetables – as people have done for millennia.

 

*Links to the papers:

Gaziano JM et al. Multivitamins in the prevention of cancer in men: The Physicians’ Health Study II randomized controlled trial. JAMA 2012 Oct 17; [e-pub ahead of print]. (http://dx.doi.org/10.1001/jama.2012.14641)

Sesso HD et al. Multivitamins in the prevention of cardiovascular disease in men: The Physicians’ Health Study II randomized controlled trial. JAMA 2012 Nov 7; 308:1751. (http://dx.doi.org/10.1001/jama.2012.14805)

© 2012 How to Live to 110 Suffusion theme by Sayontan Sinha