Many Canadians lack sufficient vitamin D, partly because of our long, dark winters — a fact that has many experts concerned, since the body needs both calcium and vitamin D for optimum bone health. While calcium, available from milk products, beans and green leafy vegetables, is used to build strong bones, vitamin D, synthesized in the skin from sunlight and also available from fish, liver and soy, helps the absorption and regulation of calcium levels in the body.

Researchers at the Bone and Cartilage Metabolism Research Unit at the University of Liege in Belgium found that calcium/vitamin D had positive effects on bone turnover and bone density, and could also lower fracture incidence for postmenopausal women. In this study, 100 postmenopausal women were either given calcium alone or calcium/vitamin D daily for three months. The researchers found that calcium/vitamin D was significantly more effective than calcium alone to reduce secretion of the parathyroid hormone, involved in bone turnover.

Vitamin D also plays a role in musculoskeletal health, and as such can help decrease the number of falls experienced by the elderly. At the University of Basel in Switzerland, researchers studied the effects of calcium/vitamin D to prevent falls. In a double-blind study, 122 elderly women, aged 63 to 99, were given either calcium or combined calcium/vitamin D daily for three months. The results showed that calcium/vitamin D reduced the risk of falling by 49% compared with calcium alone. The researchers attributed this benefit to an improvement in musculoskeletal function.

Sources: Aging Clin Exp Res. 2002 Feb;14(1):13-7; J Bone Miner Res. 2003 Feb;18(2):343-51