Dietary Calcium Intake and Bone Loss Over 6 Years in Osteopenic Postmenopausal Women

Context: Calcium intakes are commonly lower than the recommended levels, and increasing calcium intake is often recommended for bone health. Objective: To determine the relationship between dietary calcium intake and rate of bone loss in older postmenopausal women. Participants: Analysis of observational data collected from a randomized controlled trial. Participants were osteopenic (hip T-scores between -1.0 and -2.5) women, aged >65 years, not receiving therapy for osteoporosis nor taking calcium supplements. Women from the total cohort (n = 1994) contributed data to the analysis of calcium intake and bone mineral density (BMD) at baseline, and women from the placebo group (n = 698) contributed data to the analysis of calcium intake and change in BMD. BMD and bone mineral content (BMC) of the spine, total hip, femoral neck, and total body were measured three times over 6 years. Results: Mean calcium intake was 886 mg/day. Baseline BMDs were not related to quintile of calcium intake at any site, before or after adjustment for baseline age, height, weight, physical activity, alcohol intake, smoking status, and past hormone replacement use. There was no relationship between bone loss and quintile of calcium intake at any site, with or without adjustment for covariables. Total body bone balance (i.e., change in BMC) was unrelated to an individuals' calcium intake (P = 0.99). Conclusions: Postmenopausal bone loss is unrelated to dietary calcium intake. This suggests that strategies to increase calcium intake are unlikely to impact the prevalence of and morbidity from postmenopausal osteoporosis.