Canadian Cancer Society Announces Vitamin D Recommendation

Main Category: Cancer / Oncology
Also Included In: Dermatology;  Public Health
Article Date: 21 Jun 2007 - 1:00 PST

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The Canadian Cancer Society is recommending a specific amount of Vitamin D supplementation for Canadians to consider taking. This first-time recommendation is based on the growing body of evidence about the link between Vitamin D and reducing risk for colorectal, breast and prostate cancers.

"The evidence is still growing in this area, but we want to give guidance to Canadians about this emerging area of cancer prevention based on what we know now," says Heather Logan, Director, Cancer Control Policy, Canadian Cancer Society. "As we find out more we will update our recommendation."

In consultation with their healthcare provider, the Society is recommending that:

-- Adults living in Canada should consider taking Vitamin D supplementation of 1,000 international units (IU) a day during the fall and winter.

-- Adults at higher risk of having lower Vitamin D levels should consider taking Vitamin D supplementation of 1,000 IU/day all year round. This includes people:

- who are older;
- with dark skin;
- who don't go outside often, and
- who wear clothing that covers most of their skin.

"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," says Logan. "More research is needed to clearly define the amount of Vitamin D that will maximize health benefits."

Logan explains that Canada's geographic location was a strong factor in the Society's decision making about the recommendation.

"Where a person lives is one important factor in how much Vitamin D they can produce from the sun. Because of our country's northern latitude, the sun's rays are weaker in the fall and winter and Canadians don't produce enough Vitamin D from sunlight during this time."

Research findings announced today add to the mounting evidence in this area. A study published in The American Journal of Clinical Nutrition found that taking Vitamin D supplements and calcium substantially reduces all-cancer risk in post menopausal women. Specifically, the researchers found that the higher the levels of Vitamin D in the blood, the lower the relative risk of developing cancer. As well, another study released in May, suggests that women who consume more calcium and vitamin D may be less likely to develop breast cancer before menopause.

In addition to taking supplements, people can get Vitamin D by exposure to the sunlight and in their diets. However, Logan cautions Canadians about relying too much on getting Vitamin D through exposure to sunlight.

"It's important to remember that a few minutes a day of unprotected sun exposure is usually all that is needed for some people to get enough Vitamin D," says Logan. "It's not a good idea to rely solely on the sun to obtain Vitamin D. For some people, it's possible that just a few minutes of unprotected sun exposure every day could increase skin cancer risk."

Logan says a large-scale clinical trial would help provide more answers about the amount of Vitamin D needed to maximize health benefits, and the long-term risks, if any, of taking large doses of the vitamin.

"The Canadian Cancer Society is looking seriously at what we can do to make this research happen. We will also be talking to our partners about this. We need to keep building on our knowledge about this important area of cancer prevention."

More research is also needed about the amount of sunlight exposure needed to achieve the optimum Vitamin D level.

The Society is not changing its SunSense guidelines, as skin cancer is the most frequently diagnosed cancer in Canada. The Society recommends that people reduce their exposure to the sun, particularly between 11 a.m. and 4 p.m. when the sun's rays are the strongest. Use a sunscreen with a sun protection factor (SPF) 15 or higher and SPF 30 if you work outdoors or if you will be outside for most of the day.

At this time, the Canadian Cancer Society does not have a recommendation for Vitamin D supplementation for children. The research to date about the role of Vitamin D and cancer prevention has focused on adults.

The Canadian Dermatology Association recently updated its recommendations about Vitamin D supplementation. The association's website says: "In order to lessen the health risks associated with skin cancer yet still reap the known and possible benefits of Vitamin D levels take 1,000 international units of Vitamin D supplements a day."

The Canadian Cancer Society is a national community-based organization of volunteers whose mission is to eradicate cancer and to enhance the quality of life of people living with cancer.

Canadian Cancer Society