Women with adequate levels of vitamin D are less likely to develop uterine fibroids than those with insufficient levels, a new study finds.
Uterine fibroids are noncancerous tumors of the uterus that often cause pain and bleeding in premenopausal women and are the leading cause of hysterectomy in the United States.
The study, by researchers at the National Institute of Environmental Health Sciences (NIEHS), included more than 1,000 women, aged 35 to 49, living in the Washington, D.C., area from 1996 to 1999. Blood samples taken from the women were analyzed for vitamin D levels. Those with sufficient amounts of vitamin D were 32 percent less likely to develop uterine fibroids than those with insufficient vitamin D levels.
The researchers also found that women who spent more than an hour outside per day had a 40 percent decreased risk of fibroids. The body makes vitamin D when the skin is exposed to sunlight. Vitamin D also comes from food and supplements.
Fewer black women than white women had sufficient vitamin D levels, the study found, but the reduction in the risk of fibroids was about the same for both white and black women with sufficient vitamin D levels.
"It would be wonderful if something as simple and inexpensive as getting some natural sunshine on their skin each day could help women reduce their chance of getting fibroids," study leader Donna Baird, a researcher at the NIEHS, part of the National Institutes of Health, said in an institute news release.
Although these findings are consistent with previous laboratory studies, further research is needed, Baird added.
"This study adds to a growing body of literature showing the benefits of vitamin D," Linda Birnbaum, director of the NIEHS and the National Toxicology Program, said in the news release.