Calcium, dairy products, and the risk of hip fracture in women in northern Italy

We report the relation between hip fracture and intake of calcium and dairy products in postmenopausal women age 45 years or over. We conducted a case-control study in northern Italy. We interviewed a total of 241 cases of hip fracture and 719 controls in hospital for acute, nonneoplastic, nontraumatic, nondigestive, non-hormone-related diseases during their hospital stay. We derived odds ratios (OR) and their 95% confidence intervals (CI), according to intake of calcium, milk, and cheese from multiple logistic regression equations, including terms for age, education, body mass index, smoking status, alcohol drinking, and estrogen replacement therapy. Cutoff points for extreme quintiles of calcium intake were 443 and 1,026 mg per day. Compared with the lowest quintile of calcium intake, the multivariate ORs were 1.2 (95% CI = 0.7-2.0), 1.1 (95% CI = 0.6-1.7), 1.1 (95% CI = 0.6-1.7), and 1.2 (95% CI = 0.8-2.0) for subsequent quintiles of intake. Similarly, there was no appreciable association with milk (compared with less than 7 drinks per week, ORs were 1.2 and 1.0, respectively, for 7 and more than 7 drinks per week) or cheese intake (compared with less than 4 portions per week, ORs were 1.2 for 4-6 portions and 1.0 for more than 6 portions per week). OR estimates for calcium intake (tertiles) were consistent across strata of age, education, smoking status, and alcohol drinking. Thus, within the range of variation of intake of the main sources of calcium in this population, there was little association between hip fractures in women and intake of calcium, milk, and cheese.