"Our findings suggest that vitamin D plays an important protective role against prostate cancer, especially ... aggressive disease," says lead researcher Haojie Li, MD, PhD, a research fellow at Brigham and Women's Hospital and Harvard University School of Public Health, in a news release.
"This research underscores the importance of obtaining adequate vitamin D through skin exposure to sunlight or through diet, including food and supplements," Li says. Li presented the report at the 2005 Multidisciplinary Prostate Cancer Symposium.
Prostate cancer is one of the most common types of cancer in men in the U.S., and it's the second leading cause of cancer death in men, according to the American Cancer Society. Almost 232,000 new cases will be diagnosed this year, and about 30,000 men will die of prostate cancer.
The cause is unknown, although many risk factors exist that increase the risk of this cancer. Older age, family history, and a diet high in red meat increase the risk of prostate cancer.
Experts have known that vitamin D can help stop the growth of certain cancers. Some studies have shown that the rate of prostate cancer is lower in Southern states, where sunshine is more abundant. Sunlight helps the body make vitamin D.
Vitamin D Protects Against Prostate Cancer
The study involved 1,029 men with prostate cancer and more than 1,300 healthy men. Researchers analyzed the men's blood, looking for several factors including levels of vitamin D. They found that men with the highest levels of vitamin D had significantly lower overall risk (45%) of prostate cancer, including aggressive prostate cancer, Li reports.
Also, men with a specific receptor that helps vitamin D work got greater protection if they also had high levels of vitamin D in their blood. Those men had 55% lower risk of prostate cancer and 77% lower risk of aggressive prostate cancer.
The researchers conclude that vitamin D plays a role in reducing the risk of prostate cancer and its aggressiveness.