Canadian researchers at the Samuel Lunenfeld Research Institute at Toronto's Mount Sinai Hospital interviewed 576 patients with breast cancer and 1,135 without the disease and determined that those who had been exposed to vitamin D had a significantly reduced risk of breast cancer.
The results sound promising -- but what do they really mean?
Lately it seems that every time we open a newspaper, there's a new, groundbreaking study telling us what we absolutely must stay away from. A week later, another study tells us about the benefits of getting more of that very same thing.
To cut through the confusion we went straight to the source. Dr. Julia Knight, who headed the Mount Sinai breast cancer research, gave us the straight goods on vitamin D supplements, the risks of sun exposure, age issues and other prevention measures.
The sunshine drug
Vitamin D, also known as the 'sunshine drug,' has long been believed to help prevent breast cancer, says Knight. The most effective way to get a dose of D is through sun rays absorbed by your skin.
"Enzymes in our skin make vitamin D when skin is exposed to sunlight," she says. "Another source of vitamin D is fish, who make their own vitamin D when they are exposed to sunlight." Fish that are particularly good sources of vitamin D include salmon and tuna, or cod liver oil. Milk is another way to get your vitamin D.
"Vitamin D is considered to be important for bone development and so milk is fortified with it," says Knight.
Fun in the sun
We've been told for years that sun is the enemy and now we're supposed to bask away for the sake of our health? Not exactly, says Knight.
"You don't need much sun for your body to reach its maximum level of vitamin D," she says. "In the summer, a lighter-skinned person would reach their maximum level in about 15 minutes. People with darker skin would need a bit more time."
And the SPF 30 you apply religiously? "Sunscreen would block some of the UV," says Knight. "You would have to stay in the sun longer to reach your maximum level. Of course, you should always protect yourself if you plan on being in the sun for a long period of time."
An ounce of prevention
"Clinical trials are being held to determine the effects of vitamin D supplements," says Knight. If the results are good, you could be getting your sunshine drug in pill form.
In addition to vitamin D, Knight recommends a healthy lifestyle to prevent breast cancer. "Exercise and maintaining body weight have been shown to help all forms of cancer," she says. "We also know that diet is a factor in cancer prevention but we don't yet know what components of diet are beneficial."
Knight says it's still important to talk to your physician before making lifestyle changes. "I wouldn't suggest taking or doing anything without talking to your doctor."
Nothing but a number
In the Mount Sinai study, women who worked an outdoor job (physical activity wasn't calculated), took cod liver oil, ate fish and drank milk between the ages of 10-19 and the ages of 20-29 were found to have significantly reduced breast cancer risk (between 25 and 40 per cent).
But it's not too late for women in their 30s and older.
"The results for older women didn't show as significant results but increasing vitamin D can still be beneficial," says Knight. "Nothing can guarantee you won't get breast cancer. There are too many different factors that contribute to the disease. But doing something positive for your health is never bad."