For the current study, the researchers tested the vitamin D treatment on a strain of rats genetically predisposed to developing fibroid tumors. After examining the animals and confirming the presence of fibroids in 12 of them, the researchers divided the rats into two groups of six each: those that would receive vitamin D and those that would not.
In the first group, small pumps implanted under the skin delivered a continuous dose of vitamin D for three weeks. The researchers then examined the animals in both groups. Fibroids increased in size in the untreated rats, but, in the rats receiving vitamin D, the tumors had shrunk dramatically. On average, uterine fibroids in the group receiving vitamin D were 75 percent smaller than those in the untreated group.
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.
"Additional research is needed to confirm vitamin D as a potential treatment for women with uterine fibroids," said Dr. Al-Hendy. "But it is also an essential nutrient for the health of muscle, bone and the immune system, and it is important for everyone to receive an adequate amount of the vitamin."
Fatty fish such as salmon, mackerel and tuna are the best natural sources of the vitamin. Very few foods naturally contain vitamin D. Fortified milk and other fortified foods provide an additional source of the vitamin. Vitamin D is also produced when ultraviolet rays from sunlight strike the skin.
|Contact: Robert Bock or Marianne Glass Miller|
NIH/National Institute of Child Health and Human Development