Prevent cancer with a pill?

Zoomer | July 8th, 2007

Vitamin D has long been linked with the body’s ability to maintain healthy bones and prevent the onset of osteoporosis. And now yet another study adds to the body of evidence that says the “sunshine vitamin” may also help to cut the risk of cancer.

The four-year study, conducted at Creighton University in Nebraska, found that people who took calcium and vitamin D and had higher levels in their blood were 77 per cent less likely to develop cancer after the first year, compared to those who took placebos or only calcium. The study involved 1,024 women over the age of 55.

Based on this finding, the Canadian Cancer Society now recommends that adults take vitamin D – but with caution. After consulting a doctor or healthcare provider, the society suggests that:
• Adults living in Canada 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, have dark skin and don’t go outside often or 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 Heather Logan, Director, Cancer Control Policy, Canadian Cancer Society. “More research is needed to clearly define the amount of Vitamin D that will maximize health benefits.”

The society’s decision to recommend taking vitamin D is the first of its kind. A significant factor for taking this step is Canada’s northern geographic location.

“Where a person lives is one important factor in how much vitamin D they can produce from the sun,” Logan says. “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.”

Mounting evidence of the health benefits of vitamin D
These most recent findings add to the growing evidence of the link between vitamin D and cancer. 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. Researchers also found that the higher the levels of vitamin D in the blood, the lower the risk of developing cancer.
Another study found that women who take more calcium and vitamin D may be less likely to develop breast cancer before menopause.

The sunshine vitamin
Our bodies can get vitamin D from food, sunlight and supplements.

The only natural foods containing vitamin D are egg yolk, liver and fatty fish, such as salmon, tuna, mackerel and sardines. It is also found in fortified foods and beverages such as milk, margarine and soy milk.

Exposure to sunlight triggers vitamin D synthesis in skin but in winter sunlight exposure is insufficient to make significant amounts of it. The U.S. National Institutes of Health (NIH) says that 10-15 minutes of exposure to the face, hands or back is usually enough to provide sufficient vitamin D. (If you use a sun protection factor (SPF) of 8 or greater, you block your body’s ability to synthesize sunlight into vitamin D, according to the NIH.) But the initial 10-15 exposure to sunlight should be immediately followed by application of sunscreen with an SPF of at least 15.

While the Canadian Cancer Society agrees that short periods of sun exposure can be beneficial, it says too much can increase risk for skin cancer and cataracts. In order to avoid switching risk for one cancer for another, the society continues to advise following its Sunsense guidelines:

• Protect yourself and your family from the sun, particularly between 11 a.m. and 4 p.m. when the sun’s rays are at their strongest, or any time of the day when the UV Index is 3 or more.

• Use a sunscreen with a SPF of 15 or higher – and SPF 30 if you work outdoors or if you will be outside for most of the day. Look for “broad spectrum” sunscreen that offers protection against two types of ultraviolet rays, UVA and UVB.

Too much of a good thing
In response to the growing evidence on the healthy benefits of vitamin D, Health Canada announced it will evaluate the efficacy and safety of Vitamin D across all age groups.

“Before Health Canada can issue a revised recommendation concerning vitamin D, a comprehensive review that looks at both benefits and safety needs to be undertaken,” the agency said.

In the meantime, Health Canada warns about the risks of taking too much vitamin D. People are advised not exceed the tolerable upper intake level set for adults at 2000 IU/day from all sources of vitamin D, including milk and over the counter supplements.

Health risks of extremely high doses of vitamin D include development of kidney stones as well as nausea, vomiting and constipation.

On the Web:
Canadian Cancer Society
Health Canada
National Institutes of Health