Abstract

Background: Increased dietary calcium intake has been proposed as a population-based public health intervention to prevent osteoporotic fractures.We have examined whether calcium supplementation decreases clinical fracture risk in elderly women and its mechanism of action.Methods: Five-year, double-blind, placebo-controlled study of 1460 women recruited from the population and older than 70 years (mean age, 75 years) who were randomized to receive calcium carbonate, 600 mg twice per day, or identical placebo.The primary end points included clinical incident osteoporotic fractures, vertebral deformity, and adverse events ascertained in 5 years.Bone structure was also measured using dual x-ray absorptiometry of the hip and whole body, quantitative ultrasonography of the heel, and peripheral quantitative computed tomography of the distal radius.Results: Among our patients, 16.1% sustained 1 or more clinical osteoporotic fractures.In the intention-to-treat