Vitamin D: an evidence-based review.

Vitamin D is a fat-soluble vitamin that plays an important role in bone metabolism and seems to have some anti-inflammatory and immune-modulating properties. In addition, recent epidemiologic studies have observed relationships between low vitamin D levels and multiple disease states. Low vitamin D levels are associated with increased overall and cardiovascular mortality, cancer incidence and mortality, and autoimmune diseases such as multiple sclerosis. Although it is well known that the combination of vitamin D and calcium is necessary to maintain bone density as people age, vitamin D may also be an independent risk factor for falls among the elderly. New recommendations from the American Academy of Pediatrics [corrected] address the need for supplementation in breastfed newborns and many questions are raised regarding the role of maternal supplementation during lactation. Unfortunately, little evidence guides clinicians on when to screen for vitamin D deficiency or effective treatment options.