“VITAMINS may shorten your life” was the most unexpected headline of the week. It arose after the publication of a review of 67 studies involving nearly a quarter of a million people taking antioxidant vitamin supplements (such as A, E and C). Far from showing benefit, it indicated that some, such as vitamin A, seemed to increase mortality.

This is a long way from other stories that suggest the benefits of supplements. Confusing, isn't it? The problem is that studying the real effect of vitamins is incredibly hard. Focusing on one nutrient in isolation has proved to be a fine way to explain specific symptoms of one disease, such as those typically caused by vitamin deficiency - vitamin C and scurvy, for instance. But it's not that useful when trying to assess the impact of vitamins on chronic conditions or even on death rates.

This is partly because the way that supplements affect our health can be influenced by many factors, significantly our diet. Drinking tea, for example, can inhibit the uptake of iron from food. Other influences are genes, physical fitness, existing disease, income levels, whether we smoke or drink . . .

And when researchers try to keep track of all these variables, and what foods and supplements we take, there's another problem: we're very unreliable witnesses. We either get muddled about what we have or haven't eaten, or we simply lie when confronted with a nice dietitian with a clipboard.

There's yet another problem. Costly trials involving enormous numbers of people over long periods of time are required to demonstrate the long-term effect of vitamins. People's diets and habits can change considerably over these periods, making the results less reliable.

Meanwhile, the waters are muddied by the booming supplements business, which is worth £330million a year in the UK alone, the financial health of which is dependent on persuading us that our health is in jeopardy without its wares. Ironically, those most likely to be seduced by the marketing hype are those with the least need for supplements: health- conscious middle-class types.

So what does this latest review mean for us? It certainly doesn't mean that those of us taking multivitamins are going to suffer an early death - they were not covered in the review. For those of us who take supplements of individual antioxidants, the picture is still far from clear. What we can say is that if there are benefits in taking single antioxidant supplements, they are very small indeed.

Stopping them is unlikely to affect your health adversely and will have a positive effect on your bank balance.

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