What are the risk factors for Vitamin D deficiency?

According to a 2011 study (Forrest, et al. Nutritional Research), 41.6% of adults in the US are deficient. This number goes up to 69.2% in Hispanics and 82.1% in African-Americans. Despite previous thoughts, distance from the equator is not associated with vitamin D deficiency as long as individuals have some sunlight exposure. Risk factors for vitamin D deficiency include being overweight or obese, having dark skin, not drinking milk, staying indoors, and old age.

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