Bone as the Calcium Nutrient Reserve

Abstract

Osteoporotic fractures are common and devastating occurrences. Many lifestyle and hereditary factors contribute to fracture risk. Several components of the diet influence risk of osteoporosis in older men and women and the best studied of these are calcium and vitamin D. This chapter focuses on the role of calcium in bone health in older men and women. It includes a review of the physiology and determinants of calcium absorption and a summary of the evidence that calcium intake influences the rate of bone remodeling and bone loss in older individuals. The limited available evidence that calcium alters fracture rates will also be addressed. The National Academy of Sciences now recommends that men and women age 51 yr and older consume 1200 mg/d of calcium. Although food sources of calcium are preferred, many individuals will need supplements in order to meet their calcium requirement. Supplement absorbability and optimal dosage schedules are reviewed.