Surgery is generally the only treatment for uterine fibroids, the most common noncancerous tumors in women of childbearing age. Some 200,000 U.S. women have the procedure every year, at a cost $34 billion a year.
But a new study funded by the National Institutes of Health show that vitamin D may be an effective new treatment.
About thirty percent of women 25-44 have fibroid-related symptoms including lower back pain, heavy vaginal bleeding and painful menstrual periods. The fibroids can cause infertility, miscarriage and pre-term labor.
But fibroids are three to four times more common in African-American women, who are also about 10 times more likely to be deficient in vitamin D than white women, according to NIH researchers.
The researchers had found in previous studies that vitamin D inhibited the growth of fibroid cells in lab cultures. So, they decided to do more research.
"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.
Findings were published in the journal Biology of Reproduction.
The study used rats predisposed to developing the fibroids. Six rats with the tumors were given vitamin D injections for three weeks and six more with tumors were not treated. Fibroids grew in the untreated rats and shrunk by 75 percent in the ones given the vitamin.
The dose was equivalent to a human dose of 1,400 international units. The recommended amount for adults is 600 units daily, though 4,000 units is considered safe. It is considered good for muscle, bone and immune system health. Fatty fish such as salmon and tuna and fortified milk contain the vitamin. It's also generated by sunlight.
The researchers said more research is needed before vitamin D can be used as a treatment.