There's a debate over suntans. Some health experts say there is no such thing as a "safe" suntan. But we do need exposure to the sun because it is a source of Vitamin D (the so-called "sunshine vitamin"). You also could call it the "bone vitamin" because it prevents health conditions, like rickets, in which developing bones grow abnormally. Lack of Vitamin D causes bone problems for adults, too. Those older than age 50 need twice as much of the vitamin as younger people. And, if you live in a far northern state, you probably do not get enough Vitamin D from sunshine in the winter months. Also at risk are those who suffer from colitis because they do not absorb nutrients adequately.

The solution, then, is a combination of diet and sun exposure. Wild-caught salmon, herring, egg yolks, mushrooms and fortified milk contain the vitamin. This chart shows levels of the vitamin in different foods. How much exposure to the sun you need varies by where you live and the season. One rule of thumb is 10 to 30 minutes three times a week (30 to 90 minutes in all).

You don't have to stay cooped up during the day, though. Wear sunscreen when you are outside for long periods in the middle of the day. At the beach, sit in the shade of an umbrella.