A new study indicates that older women who consume too much vitamin A may increase their risk of hip fracture. Researchers found that women with the highest total intake of vitamin A, from both fortified food and multivitamin supplements, had double the risk of hip fracture compared to women with the lowest intake. The study appeared in the January 2, 2002, issue of the Journal of the American Medical Association.
Vitamin A is needed for healthy skin and hair and for bone growth. However, high levels of vitamin A may inhibit vitamin D’s ability to help the body absorb calcium, according to lead author Diane Feskanich, ScD, an epidemiologist at Brigham and Women’s Hospital in Boston. The adverse effects appear to result from too much retinol, the true form of vitamin A found in liver, fish oils and supplements. Foods rich in the beta-carotene type of vitamin A—for example, dark, leafy vegetables—don’t appear to have adverse effects since the body converts beta-carotene into vitamin A only as needed. The researchers concluded that the amount of retinol added to fortified foods and vitamin supplements may need to be reassessed.
Over an 18-year period, researchers evaluated dietary questionnaires from 72,337 nurses participating in the Nurses’ Health Study. The participants were postmenopausal women, ranging in age from 34 to 77 years. Between 1980 and 1998, 603 hip fractures occurred. Fractures resulted from low or moderate trauma, such as falling or tripping.