Vitamin D Can Halve Risk of Some Cancers, Claims Study

By Louise Gray

A LARGE daily dose of vitamin D can lower the risk of developing common cancers by half, scientists have reported after reviewing four decades of research and evidence.

Researchers found that the “natural” form of the vitamin, known as D3, can dramatically reduce the chances of developing cancers including breast, ovarian and colon.

D3 is normally produced in the skin by the action of sunlight, which could explain lower cancer rates in climates such as the Mediterranean. But the vitamin is also obtained from foods such as milk, fish and egg yolks and could be given in supplements.

The US researchers found taking 1,000 international units (IU) of the vitamin daily could lower cancer risk by 50 per cent.

However, survival rates for Afro-Caribbean people with certain cancers are worse than for white people, and the researchers believe this could be because dark skins are not as good at making vitamin D.

The academics have now proposed supplements should be given to people as part of a public health measure to reduce cancer rates as not enough vitamin D is in the diet – a glass of milk contains only a tenth of the recommended daily amount.

However, large doses of vitamin D are dangerous. More than 2,000 IU a day can lead to the body absorbing too much calcium, and possible damage to the liver and kidneys.

The US researchers carried out a systematic review of 63 studies over the last 38 years looking at the relationship between blood levels of vitamin D and cancer risk.

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, concluded public health action is needed. He said: “

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.”

However, Prof Garland said people must be careful not to exceed 1,000 IU or sunbathe too often. He added: “Sun exposure has its own concerns. We recommend no more than 15 minutes of exposure daily over 40 per cent of the body, other than the face, which should be protected from the sun.”

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

Vitamin D deficiency may account for several thousand premature deaths in the US each year. The study found particularly high rates in the north-eastern US, and among darker skinned individuals, who are at increased risk due to a lack of sunshine-generated vitamin D.

The Scottish Executive, which would be in charge of any public health initiatives, said it would look at the research “with interest”.

However, Sara Hiom, the head of health information at Cancer Research UK, was cautious. She said: “The evidence linking vitamin D levels with cancer risk is complex and confusing. There is evidence to suggest that the vitamin plays a role in keeping cells healthy. But further research is needed to understand what role vitamin D may play in preventing cancer in humans.”

Jim Cassidy, the head of the Beatson Cancer Centre in Glasgow, also said there needed to be more research. “I think that claim will have to be viewed with some caution.”

Healthier eating

THE sunshine vitamin D3 is generated by modest exposure to sunlight.

However, health experts recommend it is safer to get the vitamin through supplements and food.

The best natural food sources are fatty fish, egg yolks and cod liver oil. Some foods are supplemented with D3 including margarine, milk, some breads and cereals.