American researchers who analyzed results from two large United States studies involving 100,000 people found those who ate the most fruit and vegetables had lower rates of heart disease but their "healthy" diets had no effect on the incidence of cancer.

The finding undermines one of the basic tenets of the healthy lifestyle. Governments worldwide have promoted the five-a-day strategy for increasing fruit and vegetable consumption as a key defence against cancer and other chronic diseases.

Britain's Department of Health said in the NHS Plan published in 2000 that eating more fruit and vegetables was the second most effective way of preventing cancer, after not smoking.

The World Health Organisation, the Europe Against Cancer organisation and the US National Cancer Institute back the five-a-day strategy.

The World Cancer Research Fund, based in Britain, claims "30 to 40 per cent of cancer cases could be prevented by making healthier food and lifestyle choices".

That claim is now in doubt following a report in the Journal of the National Cancer Institute by researchers from the Harvard School of Public Health. Combining results from 71,000 women participants in the Nurses Health Study established in 1976 and 37,000 men in the Health Professionals study launched in 1986, the researchers compared consumption of fruit and vegetables with the incidence of cardiovascular disease and cancer.

Overall, those who ate at least five portions of fruit and vegetables daily had a 12 per cent lower risk of a heart attack or stroke compared with those who ate fewer than 1.5 portions a day. But there was no effect on overall cancer incidence, and the researchers felt the protective effect of fruit and vegetable intake "may have been overstated".

Cancer Research UK has raised doubts about the accuracy of the findings.

Spokeswoman Dr Lesley Walker said accurate measurement of food intake was important, yet in the health professionals' study, participants had been asked to record how many portions of fruit and vegetables they ate daily in the previous year.

"Most of us would struggle to remember how many portions we had eaten in the last two weeks," she said.

Cancer experts were now placing their faith in the detailed European Prospective Investigation into Cancer and Nutrition, which had recruited 500,000 people in 10 countries, said Dr Walker.

The study has been running for 10 years and participants keep daily food diaries as well as contributing regular blood and urine samples.

- INDEPENDENT

Five-a-day?

In New Zealand and many other countries, people are urged to eat five helpings of fruit and vegetables each day to protect against a range of diseases, including cancer.

The study authors suggest the five-a-day strategy works against heart disease but may not be as effective against cancer.
 

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