Dr. Edward Giovannucci, professor of medicine at Harvard, said vitamin D helps prevent 30 deaths from other forms of cancer for every one caused by skin cancer.

Instead of a constant coating of sunscreen, they recommend spending 15 minutes or so in the sun without it a few times a week.

The advice follows evidence from the U.S. that vitamin D, made by the skin from ultraviolet rays, helps protect against cancers of the colon, prostate, lungs and skin.

Dr. Edward Giovannucci, professor of medicine at Harvard, said the vitamin helps prevent 30 deaths from any of these forms of cancer for every one caused by skin cancer.

"I would challenge anyone to find an area of nutrient or any factor that has such consistent anticancer benefits as vitamin D," he said. "The data are quite remarkable." The American Cancer Society is reviewing its sun protection guidelines as a result of the findings.

Its chief epidemiologist, Dr. Michael Thun, said, however, that the advice did not mean sunseekers should go overboard. He said they should aim to get most of their vitamin D from their diets.

The evidence, from four separate studies, was presented to the American Association for Cancer Research last week. Researchers found those with high levels of vitamin-D were less likely to suffer from cancer because the vitamin stifles abnormal cell growth and stops the formation of blood vessels that feed tumors.

Those living in northern regions were more likely to have cancer than those who got sunshine all year round.

Dr. Allan Halpern, head of dermatology at Memorial Sloan-Kettering Cancer Centre in New York, said: "I find the evidence (for vitamin D's benefits) to be mounting and increasingly compelling."