Vitamin D downgrade as scientists advise there is no real proof it fights cancer

The sunshine vitamin has been widely credited with warding off cancer, strengthening bones and cutting the risk of heart disease and diabetes.

But a ten-year study of thousands of men and women has questioned its cancer-fighting properties. It was found that those with high levels were no less likely to die of the disease than others.

The statistics for bowel cancer were the only ones to show a clear benefit from taking the vitamin. Cancer experts who carried out the U.S. government-funded research said not enough is known about the benefits and limitations to use it for the prevention or treatment of disease.

They looked at how vitamin D affected the health of almost 17,000 men and women and started by measuring the amount in their blood.

A decade later, 536 of the volunteers had died from cancers ranging from lung cancer to breast cancer. Analysis carried out at the National Cancer Institute in Maryland did not find a link between the risk of death from all types of cancer and vitamin D.

Those with high levels of the vitamin were, however, 72 per cent less likely to die of bowel cancer which claims 16,000 lives a year in Britain. Only lung cancer kills more.

It was recently estimated that almost 30,000 cases of breast and bowel cancer could be prevented each year if Britons spend more time in the sun.

Although it is found in food, particularly oily fish such as salmon, mackerel and tuna, most of the vitamin D in our bodies is made when our skin is exposed to sunlight.

Researchers from the Office of Dietary Supplements in the U.S. said: "Health professionals and the public should not assume that vitamin D is a magic bullet and consume high amounts of it.

"More definitive data on both the benefits and potential adverse effects of high doses are urgently needed."

In Britain, the Food Standards Agency says most of us should get all the vitamin D we need from a combination of a balanced diet and a little sunlight.

It recommends that pregnant and breastfeeding women take a 0.01mg supplement each day.

Ed Yong, of Cancer Research UK, said: "This is a large study, but it's only one piece of the jigsaw. It is still unclear how big a part vitamin D plays in the fight against cancer, or how much vitamin D you need for good health.

"The best advice is to get a variety of different nutrients through a healthy, balanced diet, rather than relying on supplements."