Vitamin D, not calcium, key for postmenopausal women

Vitamin D rather than calcium intake is important in protecting postmenopausal women from fractures associated with osteoporosis, US researchers confirm.

Researchers at the Brigham and Women's Hospital and the Harvard Medical School, Boston found that an adequate vitamin D intake can lower the risk of osteoporotic hip fractures in postmenopausal women. However consumption of calcium, both in supplement form and in food, failed to have any effect.

The researchers noted that short trials of calcium supplementation show that it reduces loss of bone density in postmenopausal women; longer observational studies do not generally find a lower risk of hip fracture with higher-calcium diets, they report.

As fewer studies have focused on vitamin D in preventing postmenopausal osteoporosis or fractures, they assessed relations between post-menopausal hip fracture risk and calcium, vitamin D, and milk consumption. The study is published in the February 2003 issue of the American Journal of Clinical Nutrition​.

In an 18-year prospective analysis in 72,337 postmenopausal women, dietary intake and nutritional supplement use were assessed at baseline in 1980 and updated several times during follow-up. The team found 603 incident hip fractures resulting from low or moderate trauma. Relative risks from proportional hazards models were controlled for other dietary and non-dietary factors.

Women consuming 12.5 µg of vitamin D daily from food plus supplements had a 37 per cent lower risk of hip fracture than did women consuming less than 3.5 µg daily. Total calcium intake was not associated with hip fracture risk however, just as milk consumption was also not associated with a lower risk of hip fracture.

The researchers confirmed the need for an adequate vitamin D among post-menopausal women, and recommended that those women who consume less than the recommended intake of vitamin D, should take supplements or eat more dark fish.