Articles Address Role of Vitamin D in Cardiovascular Disease, Cancer, Fracture Prevention
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Two articles in the December 20, 2011, issue of AnAnnals of Internal Medicine examine the role of vitamin D deficiency and supplementation in cardiovascular disease, cancer, and fracture prevention.
A narrative review by McGreevy and Williams discusses the physiology and definition of vitamin D deficiency, evaluates the worldwide prevalence of vitamin D deficiency, and discusses recent evidence for the association between hypovitaminosis D and cardiovascular disease. According to the authors, emerging evidence indicates that vitamin D deficiency, cardiovascular disease, and endothelial dysfunction are linked by biological associations; however, no clear evidence indicates that vitamin D supplementation has a role to play in the prevention of cardiovascular disease, outside of clinical studies. Few randomized, controlled trials have evaluated the effect of vitamin D replacement on cardiovascular outcomes, and the results have been inconclusive or contradictory. The authors conclude that carefully designed, randomized, controlled trials are essential to evaluate the role of vitamin D supplementation in reducing cardiovascular disease.
The systematic review and meta-analysis by Chung and colleagues was conducted in support of the forthcoming U.S. Preventive Services Task Force recommendations on vitamin D with or without calcium supplements for preventing cancer and fractures. The review includes 19 randomized, controlled trials (3 for cancer and 16 for fracture outcomes) and 28 observational studies (all for cancer outcomes). Meta-analysis revealed that combined vitamin D and calcium supplementation can reduce fracture risk in older persons, but the effects may be smaller among community-dwelling older adults than among institutionalized elderly persons. The optimum dose and dosing regimens are unclear, and supplementation may increase the risk for renal and urinary tract stones. The available evidence is not sufficiently robust to draw conclusions regarding the benefits or harms of vitamin D supplementation for the prevention of cancer. Limited data from clinical trials suggest that high-dose vitamin D supplementation (1,000 IU/day) can reduce the risk for total cancer; in contrast, data from observational studies suggest that higher blood 25-hydroxyvitamin D concentrations might be associated with increased risk for cancer.
Ann Intern Med. 2011;155:820-6.
Ann Intern Med. 2011;155:827-38.