A new report casts some light on a link between Vitamin D levels and breast cancer progression. In the Canadian study, low blood levels of D were strongly linked to breast cancer diagnosis--and women with inadequate levels of the vitamin in their blood at the time of diagnosis had a higher risk of the cancer spreading and nearly twice the risk of death. It's not the first time the vitamin, produced in the body when the skin is exposed to sunlight, has been linked to a variety of diseases, including cancers and heart disease.
Three Things You Need to Know:
1. The study did not prove low levels of Vitamin D cause worse breast cancer outcomes--and it certainly didn't prove that raising levels of the vitamin level will improve those outcomes. The study simply observed links between levels and disease. Vitamin D blood levels may be a "marker" for good health, which helps the body fight off cancer.
2. Having said that, enough evidence of a link is accumulating about protective benefits of Vitamin D that some physicians recommend brief sunlight exposure as a way to build D levels in the blood. Their recommendation is to get 10 minutes of sun exposure on the arms and/or legs, without sunscreen, a few days per week. The flip side of sun exposure is increased skin cancer risk, however. The more conservative recommendation is to use Vitamin D supplements in consultation with your doctor.
3. Looking at the stats, there's bad news/good news: Among women diagnosed with early stage breast cancer entering the study, only 24 percent had adequate levels of D. The better news: 83 percent of the women with adequate D levels were alive without cancer spread 10 years later. So were 79 percent of women with inadequate D levels and 69 percent of those who had a significant deficiency.
So: considering hedging your bets? Talk to your doctor. Some physicians recommend blood tests to check for D levels, and may recommend sunlight, supplements or other risk-reduction strategies.
For some background, here's an excellent post by one of our breast cancer experts, PJ Hamel, on Vitamin D and breast cancer. And here's one by Dr. William Davis on the link between heart disease and Vitamin D.
Here's a SharePost by yours truly on 2007 study on cancer and Vitamin D.
The federal government's Office of Dietary Supplements has this excellent overview of Vitamin D research.