Sun

All life on earth depends on the sun. Humans evolved in its constant presence, and we require the sun's UV rays to synthesize the vitamin D essential for a healthy body.

But if you follow conventional wisdom, you'll wear a constant layer of sunscreen, cover every exposed inch of skin, and stay indoors during the high sun hours of 10 am to 2 pm. Sunbathing is as passé as disco, and your friends may voice concern if you're not slathering on the SPF 100 sunscreen every 15 minutes. After all, if we want to prevent skin cancer, we have to avoid the sun, right?

Unfortunately, as with many things in life, the answers are not that simple. It's now clear that the general American public is deficient in vitamin D, possibly due to the well-intentioned advice to shun the sun. Several conditions can be attributed to low levels of D, including certain types of cancers, cardiovascular disease, osteoporosis, autoimmune diseases, severe asthma in children, and mental decline in older adults. Symptoms of low vitamin D are fatigue, muscle pain and cramping, joint pain, weight gain, poor sleep, lack of concentration, and headaches.

There's no question that we need vitamin D. The best way to get it is directly from the source, but we want to avoid skin cancer. How do we solve this dilemma?