CALCIUM INTAKE AND FRACTURE RISK - RESULTS FROM THE STUDY OF OSTEOPOROTIC FRACTURES

The relation between dietary calcium, calcium, and vitamin D supplemen ts and the risk of fractures of the hip (n=332), ankle (n=210), proxim al humerus (n=241), wrist (n=467), and vertebrae (n=389) was investiga ted in a cohort study involving 9,704 US white women aged 65 years or older, Baseline assessments took place in 1986-1988 in four US metropo litan areas. Dietary calcium intake was assessed at baseline with a va lidated food frequency questionnaire, Data on new nonvertebral fractur es were collected every 4 months during a mean of 6.6 years of follow- up; identification of new vertebral fractures was based on comparison of baseline and follow-up radiographs of the spine done a mean of 3.7 years apart, Results were adjusted for numerous potential confounders, including weight, physical activity, estrogen use, protein intake, an d history of falls, osteoporosis, and fractures, There were no importa nt associations between dietary calcium intake and the risk of any of the fractures studied. Current use of calcium supplements was associat ed with increased risk of hip (relative risk=1.5, 95% confidence inter val 1.1-2.0) and vertebral (relative risk=1.4, 95% confidence interval 1.1-1.9) fractures; current use of Turns antacid tablets was associat ed with increased risk of fractures of the proximal humerus (relative risk=1.7, 95% confidence interval 1.3-2.4). There was no evidence of a protective effect of vitamin D supplements, Although a true adverse e ffect of calcium supplements on fracture risk cannot be ruled out, it is more likely that our findings are due to inadequately controlled co nfounding by indications for use of supplements. In conclusion, this s tudy did not find a substantial beneficial effect of calcium on fractu re risk.