Vitamin D has been found to shrink the size of uterine tumors, a new laboratory study shows.
Researchers, funded by the National Institutes of Health, said treatment with the “sunshine vitamin” reduced the size of benign uterine fibroids in laboratory rats and may also point the way to successful therapies for women.
Uterine fibroids in and around the uterine wall are the most common noncancerous tumors in women of childbearing age. Nearly one-third of women 25 to 44 years of age report fibroid-related symptoms, such as lower back pain or painful menstrual periods.
Researchers at Vanderbilt University Medical Center and Meharry Medical College in Nashville tested the vitamin D treatment on six rats with fibroid tumors. Six others with tumors did not receive vitamin D.
After three weeks, researchers found fibroids increased in size in the untreated rats, but the tumors shrank dramatically in those receiving vitamin D. On average, uterine fibroids in the group receiving vitamin D were 75 percent smaller than those in the untreated group, they said.
The amount of vitamin D the rats received each day was equivalent to a human dose of roughly 1,400 international units. The recommended amount of vitamin D for teens and adults age 70 and under is 600 units daily, although up to 4,000 units is considered safe for children over age 9, adults, and for pregnant and breastfeeding females.
"The study results provide a promising new lead in the search for a non-surgical treatment for fibroids that doesn't affect fertility," said Louis De Paolo, chief of the Reproductive Sciences Branch of the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development, which funded the study.
The findings appeared online in the journal Biology of Reproduction.