Vitamin D and Calcium Supplementation in Women: Making Sense of Conflicting Data

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Many clinicians are confused about the benefits and risks of vitamin D and calcium supplementation for midlife and older women. We offer guidance on the appropriate use of these supplements. Vitamin D Long recognized as important for skeletal health, vitamin D has garnered recent interest for its possible nonskeletal benefits. This vitamin is synthesized in the skin in response to sunlight and can also be ingested as vitamin D3 (cholecalciferol) or vitamin D2 (ergocalciferol). Natural dietary sources of vitamin D are few and include fatty fish and egg yolks. Vitamin D is also commonly added to milk and some other dairy products, cereals, and orange juice. Vitamin D is hydroxylated in the liver to 25-hydroxyvitamin D [25(OH)D], the major circulating metabolite, and is then further converted to 1,25-dihydroxyvitamin D (calcitriol). A recent evidence-based Institute of Medicine (IOM) report1,2 provides guidelines about the amount of vitamin D that most North American women should consume. The IOM's review confirmed that vitamin D clearly confers bone benefits, but found that current data are insufficient to conclude that it lowers risk for nonskeletal diseases (e.g., cardiovascular disease [CVD], diabetes, cancer); thus, the IOM based its recommendations only on the amount required for bone health: Because the IOM …