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Sunshine Vitamin 'Cuts Cancer Risk'

Posted on: Wednesday, 28 December 2005, 06:00 CST

By John Von Radowitz

A large daily dose of vitamin D can lower the risk of developing common cancers by up to 50%, scientists said yesterday.

Researchers found that the "natural" form of the vitamin, known as D3, can dramatically reduce the chances of developing breast, ovarian and colon cancer, as well as others.

Taking 1,000 international units (IU) of the vitamin daily could lower an individual's cancer risk by 50%, they said.

Such large doses of vitamin D must be treated with caution. More than 2,000 IU a day can lead to the body absorbing too much calcium, and possibly damage the liver and kidneys.

D3 is normally produced in the skin by sunlight, but is also obtained from certain foods ( but a glass of milk, for instance, contains only 100 IU of the vitamin.

Survival rates for Afro-Caribbean people with certain cancers are worse than for white people, possibly because dark skins are not as good at making vitamin D.

The US researchers carried out a systematic review of 63 studies looking at the relationship between blood levels of vitamin D and cancer risk. The papers, published worldwide between 1966 and 2004, included 30 investigations of colon cancer, 13 of breast cancer, 26 of prostate cancer and seven of ovarian cancer.

Analysis showed that, for at least some cancers, the vitamin D factor could not be ignored.

Professor Cedric Garland, from the University of California at San Diego, who led the review study, said: "A preponderance of evidence, from the best observational studies the medical world has to offer, gathered over 25 years, has led to the conclusion that public health action is needed.

"Primary prevention of these cancers has largely been neglected, but we now have proof that the incidence of colon, breast, and ovarian cancer can be reduced dramatically by increasing the public's intake of vitamin D."

The recommended intake of 1,000 IU of vitamin D3 a day is half the safe upper limit set by the US National Academy of Sciences.

In the absence of sunshine, a beneficial level of vitamin D can be obtained from a combination of food sources and supplements, the scientists said. "You have to work fairly hard to reach 1,000 IU a day," said Prof Garland.

"Sun exposure has its own concerns and limitations. We recommend no more than 15 minutes of exposure daily over 40% of the body, other than the face, which should be protected from the sun.

"Dark-skinned people, however, may need more exposure to produce adequate amounts of vitamin D, and some fair-skinned people shouldn't try to get any vitamin D from the sun. The easiest and most reliable way of getting the appropriate amount is from food and a daily supplement."

The findings are published today in the American Journal of Public Health.

Vitamin D deficiency may account for several thousand premature deaths from cancer each year in the US, the scientists said.

The study found people in the north eastern US, and darker skinned individuals, were at increased risk because of a lack of sunshine-generated vitamin D.

Prof Garland said: "African-American women who develop breast cancer are more likely to die from the disease than white women of the same age."

Source: The Journal - Newcastle-upon-Tyne

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