NEW YORK (Reuters Health) – Postmenopausal women in the US who consume 3000 µg or more of vitamin A per day are at a significantly increased risk for hip fracture from low to moderate trauma, according to a report in the Journal of the American Medical Association for January 2.
Dr. Diane Feskanich from Brigham and Women's Hospital, Boston, and colleagues collected data on 72,337 postmenopausal women who participated in the Nurses' Health Study. From 1980 to 1989 there were 603 hip fractures resulting from low to moderate trauma.
Compared to women whose intake of vitamin A was less than 1250 µg per day, women who consumed 3000 µg per day or more had a significantly increased risk of hip fracture (relative risk 1.48, p for trend = 0.003), the researchers found.
The increased risk of hip fracture was tied to retinol intake. The relative risk was 1.89 (p for trend < 0.001) comparing 2000 or more µg/day versus 250 µg per/day or less), Dr. Feskanich's team notes. Beta-carotene intake was not associated with a significantly increased risk of hip fracture.
Women taking a specific vitamin A supplement had a relative risk of 1.40 for hip fracture compared with women not taking a vitamin A supplement.
Among women not taking a vitamin A supplement, the intake of retinol from diet was associated with a significant risk of hip fracture (relative risk 1.69, p for trend = 0.05), comparing 1000 µg/day versus less than 400 µg/day, the investigators add.
Dr. Feskanich and colleagues conclude that "our findings provide further evidence that chronic intake of excessive vitamin A, particularly from retinol, may contribute to the development of osteoporotic hip fractures in women. 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 US."