An apple a day may keep cancer away.

New research shows that the higher your fruit consumption as a child, the lower your risk of developing cancer as an adult.

Researchers found that children who ate an average of 88 grams of fruit daily -- the equivalent of a big, juicy apple -- were almost 40 per cent less likely to develop cancer than children who consumed negligible amounts of fruit. Even a modest amount of fruit, such as half a kiwi a day, appears to reduce the cancer risk markedly.

The research, published in today's edition of the Journal of Epidemiology and Community Health, shows that the protective effects of fruit applied to a broad array of cancers including, surprisingly, those related to smoking.

Maria Maynard, an investigator with the British medical research council's social and public health sciences unit and lead researcher, said the antioxidants in fruit seem to be what protects against cancer. (One of the principal triggers for cancer is DNA damage caused by free radicals; antioxidants such as vitamin C and vitamin E can prevent this damage.)

But some of the anticancer benefits, particularly for colorectal cancers, may be due to the fibre content of fruit as well, she said.

However, the research did not find an association between vegetable consumption and lower cancer risk. Dr. Maynard said this is likely due to the fact that people in the study ate most of their vegetables boiled to the point where they were stripped of key nutrients.

While the benefits of eating fruits and vegetables have been highly touted in recent years, the study is the first to examine what was consumed during childhood. (Most nutritional research is based on people recalling their diet, often years later.)

In this case, researchers mined data from a nutritional study of 1,350 families that was conducted in England and Scotland from 1937-39. In the year 2000, researchers were able, using health service records, to trace almost 4,000 participants who had been children during the original survey.

A total of 483 of the members of the study group had been diagnosed with cancer. Lung and bowel cancer were most common in men, and breast, lung and bowel cancer were most common among women.

The researchers found marked differences based on childhood fruit consumption. Members of the quartile that ate the most fruit (88 grams daily, on average) were 38 per cent less likely to have been diagnosed with cancer as those in the quartile that ate the least fruit (0.6 grams daily).

The members of the two middle quartiles, with average consumption of 13 and 31 grams of fruit daily, also had a significantly lower risk. Their cancer incidence was, respectively, 30 and 34 per cent lower than those who ate virtually no fruit. These benefits held regardless of social class. (This is important because cancer rates are usually much higher among the poor.)

The researchers did not make a distinction between fresh or canned or preserved fruit. In prewar Britain, fresh fruit would have been available for only part of the year. However, canning and preserving often maintains the nutrients.

At the time of the survey, 1937-39, it was recommended that vegetables be boiled for at least an hour, and that may explain why those who ate a lot of vegetables did not see a protective effect. Now, many vegetables are steamed or boiled for no more than 10 minutes, allowing them to retain many of their nutrients.

Today, it is recommended that people eat five to 10 servings of fruit and vegetables daily, about 400 grams minimum, but the reality is that most people eat less than half that amount.