Osteoporosis is characterized by low bone mass, microarchitectural disruption, and increased skeletal fragility. Multiple therapeutic regimens have been designed to prevent or treat bone loss in postmenopausal women and older adults. The first step in the prevention or treatment of osteoporosis is ensuring adequate nutrition, particularly maintaining an adequate intake of calcium and vitamin D. Vitamin D enhances intestinal absorption of calcium and phosphate. Low concentrations of vitamin D are associated with impaired calcium absorption, a negative calcium balance, and a compensatory rise in parathyroid hormone, which results in excessive bone resorption.
Calcium and vitamin D supplementation in the treatment of osteoporosis will be reviewed here. Detailed information regarding pharmacologic therapy for osteoporosis and the role of calcium in the pathogenesis of osteoporosis is discussed separately. (See "Overview of the management of osteoporosis in postmenopausal women" and "Treatment of osteoporosis in men" and "Pathogenesis of osteoporosis".)
The optimal intake of calcium and vitamin D is uncertain. Based upon the meta-analyses discussed below, we suggest 1200 mg of calcium (total of diet and supplement) and 800 int. units of vitamin D daily for most postmenopausal women with osteoporosis. Although the optimal intake (diet plus supplement) has not been clearly established in premenopausal women or in men with osteoporosis, 1000 mg of calcium (total of diet and supplement) and 600 int. units of vitamin D daily are generally suggested. We recommend not administering yearly high-dose (eg, 500,000 units) vitamin D.
These recommendations are consistent with the Institute of Medicine Dietary Reference Intakes for calcium and vitamin D . The American Geriatrics Society and the National Osteoporosis Foundation recommend a slightly higher dose of vitamin D supplementation (at least 1000 and 800 to 1000 int. units daily, respectively), as well as calcium supplements, to older adults (≥65 years) to reduce the risk of fractures and falls [2,3]. (See 'Efficacy' below and "Falls: Prevention in community-dwelling older persons", section on 'Vitamin D supplementation'.)
Certain coexisting medical problems may alter these requirements. (See 'Coexisting medical problems' below.)