Too much vitamin A may weaken bones
may weaken older women's bones, unless they also happen to be
undergoing estrogen therapy, researchers said recently.
Heavy doses of Vitamin A either in the diet or in supplement form may weaken older women's bones, unless they also happen to be undergoing estrogen therapy, researchers said recently.
The Vitamin A compound retinol, which is found in the body, is important for vision, growth, reproduction and the immune system, but is suspected as having adverse affects on the skeletal structure, the report published a recent issue of the Journal of the American Medical Association said.
In the study of 72,000 women aged 34 to 77 participating in the two-decade Nurse's Health Study, researchers identified 603 hip fractures between 1980 and 1998 that followed only mild or moderate trauma.
Those women who ingested at least 3,000 micrograms of Vitamin A per day, putting them in the top 20% of consumers of the vitamin, were at 48% higher risk of suffering a hip fracture compared to women in the bottom 20% who ingested less than 1,250 micrograms of the vitamin daily.
"The amounts of retinol in fortified foods and vitamin supplements may need to be reassessed since these add significantly to total retinol consumption in the United States," study author Diane Feskanich of Harvard Medical School and Brigham and Women's Hospital in Boston wrote.
Vitamin A is found in liver, egg yolks, milk and dairy products, and various fruits and vegetables such as carrots and apricots. It is also often taken in supplement form.
The study found the elevated fracture risk associated with retinol was significantly reduced among those undergoing hormone replacement therapy with estrogen, which is taken to reduce the unwelcome symptoms of menopause and to ward off osteoporosis.
Heavy ingestion of beta carotene did not increase the fracture risk, the study said.
