But studies have found that as many as 70 percent of Americans are deficient.
Consumers are trying to do something about the problem. Between 2007 and 2008, sales of vitamin D supplements grew 116.5 percent, from $108 million to $234 million, according to the Nutrition Business Journal. Companies have turned this interest into a marketing tool, fortifying everything from pasta and orange juice to dairy products with vitamin D.
Some experts believe these synthetic vitamins aren't metabolized efficiently by the body, so it is best to get nutrients from "real" sources, which in the case of vitamin D is the sun.
Chemical problems • Complicating the issue is a recent report by the nonprofit Environmental Working Group (EWG) that shows the chemicals in many sunscreens pose possible health risks.
For its annual guide to safe and effective sunscreens, the EWG tested 1,800 products only one-fourth got high marks. Many sunscreens contain vitamin A, which, according to some studies, speeds the growth of tumors and lesions; other sunscreens were deemed unsafe because they contained hormone-disrupting compounds and lung-damaging vapors, the report states.
Most discouraging is that more people are wearing sunscreen, but incidence of skin cancer continues to rise. More than 2 million Americans are developing skin cancer every year.
What to do • With so many conflicting reports, what's a sunbather to do? Compromise. Spending 20 to 30 "unprotected" minutes in the sun two or three times a week will adequately boost vitamin D levels, but shouldn't harm your skin significantly. The exact amount of time will vary depending on your skin type, skin cancer concerns, age and geographic location. Start with just a few minutes and slowly build up your tolerance. Try to get this sun exposure in the morning or evening when the sun is less intense. For ideal absorption of vitamin D, about 40 percent of your skin should be exposed to the sun.
Also, when buying sunscreen, choose products that get high marks from the Environmental Working Group. Its website, www.ewg.org, lists which ones are the safest and how your current brand stacks up.
The key is to tan smart so you get the nutrients you need and avoid the toxins.