Q There have been reports in the news that scientists have found too much vitamin C can cause cancer. Should I stop taking supplements?

A Don't get me started on this! It is a good example of how nutrition matters are mis-handled by the media. There have been two papers this year, one from the UK and one from the USA, allegedly showing that vitamin C in high doses can encourage cancer. As a result some of my patients have even stopped taking supplementary C. Well, there are several problems with the papers.

1. They are both based on laboratory research, and both showed that doing things with vitamin C in a test-tube may produce small quantities of a compound that may, in theory, promote cancer. It's a very long way from that to what happens in the human body, and one of the authors of the latest study, actually said: "Absolutely for God's sake don't say vitamin C causes cancer" - not that it stopped some in the media from doing just that.

2. They were both heavily hyped and the heavy hand of the pharmaceutical industry is apparent in this. Both of the stories in the media were based on press releases, not the actual research papers, which hadn't even been published when the stories emerged. If the studies had shown that a cancer drug was toxic (which they have to be, that's how they work) we would not have heard about it in this way, if at all.

3. They have to be taken in the context of the many thousands of papers that show vitamin C is beneficial in the prevention and treatment of cancer, not to mention heart disease, stroke, ageing disorders in general, allergies, resistance to infection, etc. These, of course, get no publicity.

4. Vitamin C does not work on its own - it needs vitamin E, selenium, and many other micronutrients all working together. Studying it without these tells us nothing about what happens in real life.

5. The most recent review of the US recommendations for daily intake ("The New US Dietary Reference Intakes for Vitamins C and E", 2001), which are based on a consideration of all the evidence, and which upped the vitamin C recommendation only a couple of years ago, not only recommended increasing the dosage for C yet again to 120mg/day, but found no scientific evidence that even very large doses (up to 10,000mg daily) are toxic or have serious adverse effects. Did you hear about that in the media?

A former editor of the New England Journal of Medicine was in print last week, saying that the entire system of medical research is driven by profit.

Hardly news, you may say, but it should remind us when reading about studies such as these (not to mention articles like mine) to ask "who stands to profit?" I can't claim to be totally impartial because I do see patients privately, and sell them supplements. But I'm small fry compared to the pharmaceutical industry, or even to the health food and supplement industry.