The old adage than an apple a day keeps the doctor away looks to have acquired an important scientific dimension. It might keep cancer away too.Fresh research by scientists at Cornell University in New York shows that plant substances such as flavonoids and polyphenols, known as phytochemicals, are the essential healthy ingredients in the fruit.

“What this study shows is that the combination of phyto–chemicals plays a very important role in anti–oxidant and anti–cancer activity, and the real health benefits may come from a phytochemical mixture”, food science professor Rui Hai Liu said in a statement.

Researchers compared the anti–cancer activity in the skin and flesh of red apples. They found that just 100 gram of fresh apple with skins had the anti–cancer properties of 1,500 milligram of vitamin C. “Scientists are interested in isolating single compounds – such as vitamin C, vitamin E and beta carotene–to see if they exhibit anti–oxidant or anti–cancer benefits. It turns out that none of those works alone to reduce cancer. It’s the combination of flavonoids”, Liu said.

In laboratory tests on human colon cancer cells, the scientists found that extracts from the apple skin inhibited the proliferation of the cancer cells by 43 per cent. Extracts from the flesh of the fruit reduced it by 29 per cent.

Tests on human liver cancer cells were even more effective, inhibiting the cells at a rate of 57 per cent with the skin extract and 40 per cent with flesh extract.

The research, published in the science journal Nature, was funded by the New York Apple Research Development Program and New York Apple Association.

The researchers said the amounts of phytochemicals in apples varied from year to year and in different regions and seasons.

Vitamin C is championed by fitness fanatics for its perceived effectiveness as an antioxidant–an agent that combats destructive molecules called free radicals. These are rogue oxygen compounds produced by the body’s metabolism, but also by ultraviolet light, pollution and cigarette smoke, that damage cell membranes, thus contributing to the ageing process and vulnerability to disease, including cancer.

Vitamin C, also known as ascorbic acid, is found in fresh fruit and vegetables, especially citrus. The average daily need for an adult male is around 70 mg. Some research suggests that taking high doses, of 500 mg or more, may in fact promote oxidation in the body rather than combat it.