This article is an extract from EWG’s website.
Many people rely on the sun for making enough vitamin D. At the same time, many American adults spend very little time outdoors. People with darker skin, older people and those living farther from the equator produce less vitamin D from sunlight.
People produce less vitamin D in fall and winter, when UVB rays are less intense. People living in the northern half of the U.S. cannot make significant vitamin D from sunlight between November and early March (Vitamin D Council 2013).
Experts agree that too many Americans don’t get enough vitamin D in their daily lives (AMA 2009, IOM 2010, CDC 2012). About 8 percent of the population has a serious vitamin D deficiency, and another 25 percent is considered at risk of a deficiency (CDC 2011).
Studies have found that 70 percent of breast-fed babies were deficient in vitamin D at one month old (Wagner 2010). This is a serious problem because vitamin D plays a key role in growth and development. The federal Centers for Disease Control and Prevention have found that Mexican-Americans and African-Americans are two to three times more likely than Caucasians to have low vitamin D levels (CDC 2011). People who use more sun protection or weigh more than average are more likely to suffer from vitamin D deficiency (Looker 2008).
Full article: www.ewg.org/sunscreen/report/getting-enough-vitamin-d