Oct. 9 (HealthDay News) -- Many breast cancer patients have low levels of vitamin D, which could lead to weaker bones and increased risk of fractures, say U.S. researchers who recommend high doses of vitamin D for them.

"Vitamin D is essential to maintaining bone health, and women with breast cancer have accelerated bone loss due to the nature of hormone therapy and chemotherapy. It's important for women and their doctors to work together to boost their vitamin D intake," Luke Peppone, a research assistant professor of radiation oncology at the University of Rochester Medical Center, said in a news release from the medical cwnter.

Peppone and colleagues studied 166 women undergoing treatment for breast cancer and found that nearly 70 percent had low levels of vitamin D in their blood. The average level among the women was 27 nanograms of vitamin D per milliliter of blood. Levels of 32 nanograms per milliliter are adequate, according to the U.S. Institute of Medicine.

The lowest levels of vitamin D were in non-whites and those with late-stage breast cancer.

The researchers found that weekly supplementation with high doses of vitamin D (50,000 IU or more) boosted the levels of the vitamin among all the women.

The study was to be presented Oct. 8 at the American Society of Clinical Oncology's breast cancer symposium in San Francisco.

Previous studies have shown that nearly half of all women and men have vitamin D levels below 32 nanograms per milliliter. Along with strengthening bones, vitamin D plays an important role in cell growth and keeping the immune system strong. People obtain Vitamin D through exposure to sunlight and from foods such as milk and fortified cereals.

SOURCE: University of Rochester Medical Center, news release, Oct. 8, 2009