Higher calcium intake may not lower risk of fracture or osteoporosis

Dietary calcium intake above 750 mg does not provide added benefit against risk of fractures or osteoporosis, according to the results of a large prospective longitudinal cohort study reported in the May 24 issue of the British Medical Journal.

To investigate associations between long-term dietary calcium intake with risk of fracture of any type, hip fractures, and osteoporosis, investigators conducted a large, population-based prospective study, which consisted of 2 samples. The first was called the Swedish Mammography Cohort and included 61,433 women (born between 1914 and 1948) residing in 2 Swedish countries who responded to mailed invitations between 1987 and 1990 to a routine mammography screening. The primary outcomes were any fracture and hip fracture.

The second sample was a subcohort of 5,022 women from the Swedish Mammography Cohort, randomly selected between November 2003 and October 2009 and invited to undergo dual energy x-ray absorptiometry measurements, to provide blood and urine samples, and to have height and weight measurements taken. The secondary outcome was osteoporosis. A series of food-frequency questionnaires was used to gain in-depth knowledge of the participants’ diet, calcium intake, use of supplements and multivitamins, and lifestyle (postmenopausal oestrogen therapy and menopausal status, parity information, weight and height, smoking habits, and leisure time physical activity).

Results of the study showed an association between the lowest quintile of calcium intake and an increased risk of fractures and osteoporosis. Above the base quintile, there were only minor differences in risk. The rate of hip fracture increased in those with high dietary calcium intakes, however, the authors noted that this result should be cautiously interpreted.

“Our observational data suggest that in the prevention of osteoporotic fractures, emphasis should be placed on individuals with a low intake of calcium rather than increasing the intake of those already consuming satisfactory amounts,” the authors wrote.