At the moment, Vitamin D may fight cancer

By Terri Coles

TORONTO (Reuters) -- As winter gets closer, the days get shorter -- and along with a shortage of light, many North Americans may also find themselves short of vitamin D, a potential cancer fighter.

A study released this week showed a connection between the sunshine vitamin, so-called because sunlight is our main source, and cancer prevention. It's the latest indication that people deficient in the vitamin may be at higher risk for a variety of health problems, including cancer.

Vitamin D is a fat-soluble vitamin that is found in fish oil, but most of our food sources -- chiefly milk -- are fortified with the vitamin. That's important because people living at higher latitudes, as in Canada and parts of the United States, don't have access to strong sunlight from about October to early March. As a result, a lot of people are deficient in the vitamin, said Joan Lappe, a professor of nursing and medicine at Creighton University in Omaha, Nebraska.

Lappe said a low vitamin D intake of about 200-400 international units (IU) -- the recommended daily dosage in the United States and Canada is about 200 IU for adults - is enough to help prevent some symptoms of deficiency, such as bone-related problems. But much higher levels may provide benefits for the prevention of cancer and other diseases, she said.

The Canadian Cancer Society agrees. It recently broke with Canada's public health policy on nutrition, which is aligned with the United States, to recommend people with light skin take 1,000 IU of vitamin D daily, through supplements, during fall and winter. People with darker skin, people who spend little time outside, and those who follow a cultural or religious dress code that requires they cover most of their body should take that amount year-round.

"We're recommending 1,000 IUs daily because the current evidence suggests this amount will help reduce cancer risk with the least potential for harm," said Heather Logan, director of Cancer Control Policy at the Canadian Cancer Society, in a statement announcing the decision. "More research is needed to clearly define the amount of Vitamin D that will maximize health benefits."

The Canadian Cancer Society made the recommendation in June, after the publication of a large placebo-controlled study led by Lappe that found a group of women taking 1,100 IU of vitamin D daily showed a substantial drop in cancer risk.

The women in the study, published in the American Journal of Clinical Nutrition, were given the higher dose of vitamin D over a four-year period. The group taking the supplement had a 60 percent lower cancer incidence than the placebo group. When the women who developed cancer during the first year were removed from the results, a 77 percent reduction in cancer incidence was seen, Lappe said.