Dietary calcium intake in a cohort of individuals evaluated for low bone mineral density: a multicenter Italian study

Background A low calcium intake is a well-known factor that influences the bone mineral density (BMD) maintenance. In the presence of inadequate calcium intake, secondary hyperparathyroidism develops, leading to an increased bone turnover and fracture risk. Aims To assess the dietary calcium intake in relation with osteoporosis and fragility fracture in a cohort of Italian individuals evaluated for low BMD. Methods A 7-day food-frequency questionnaire was administered to 1793 individuals, who were consecutively referred at the Centers of the Italian Society for Osteoporosis, Mineral Metabolism and Skeletal Diseases (SIOMMMS) for low BMD. Results In 30.3% and 20.9% of subjects, the calcium intake was inadequate (< 700 mg/day) and adequate (> 1200 mg/day), respectively. As compared with patients with adequate calcium intake, those with inadequate calcium intake were younger (65.5 +/- 10.8 vs 63.9 +/- 11.5 years, p = 0.03) and they more frequently reported adverse reactions to food (3.2% vs 7.2% p = 0.01) and previous major fragility fractures (20.8% vs 27.0%, p = 0.03). Patients with calcium intake < 700 mg/day showed a higher prevalence of diabetes mellitus, idiopathic hypercalciuria and food allergy/intolerance (8.1%, 5.1%, 7.2%, respectively) than patients with calcium intake > 700 mg/day (5.3%, 3.0%, 4.1%, respectively, p < 0.04 for all comparisons), also after adjusting for age, gender and body mass index. In 30.3% of fractured subjects, the calcium intake was < 700 mg/day. Discussion In Italy, a low calcium intake is highly prevalent in individuals at risk for low BMD. Importantly, an inadequate calcium intake is highly prevalent even in patients with history of fragility fractures. Conclusions Only about a fifth of patients being assessed for low BMD in an Italian SIOMMMS referral Centre have an adequate calcium intake.