The high prevalence of inadequate serum vitamin D levels and implications for bone health.

Inadequate serum vitamin D is associated with secondary hyperparathyroidism, increased bone turnover, and bone loss, which increased fracture risk. Osteomalacia has also been observed in severe cases. Indeed, vitamin D and calcium are essential components of management strategies for the prevention and treatment of osteoporosis. Despite this, many people currently do not have adequate vitamin D levels. This problem has been documented in many studies around the world, regardless of age, health status, or latitude, and is especially common among older adults, who are also likely to have osteoporosis. Factors that contribute to low vitamin D include low exposure to sunlight, decreased synthesis in skin and reduced intestinal absorption related to aging, and limited dietary sources. Supplementation is the most effective means of correcting poor vitamin D nutrition. However, few patients with osteoporosis currently take sufficient vitamin D supplements. This review article discusses the role of vitamin D in osteoporosis and skeletal health, and summarizes what is known about the high prevalence of inadequate serum vitamin D and recommendations for supplementation. Greater awareness of the importance of vitamin D for skeletal health and more aggressive supplementation efforts are urgently needed to address this important public health problem.