We already know it's important for strong bones, but vitamin D may lengthen your life, too. Recent studies suggest D can boost your immune system and lower your risk of some types of cancer and heart disease. Since sunshine stimulates vitamin D production, is it time to do some old-fashioned sunbathing this summer?

Not so fast, sun worshippers. More than a few minutes of unprotected exposure to the sun's ultraviolet light can still give you sunburns, prematurely age your skin and increase your risk for skin cancer. As for tanning beds, forget it -- they are known to be carcinogens. But the good news is most people only need 10 minutes of summer sun a day to get plenty of vitamin D. Add a few good foods to your diet, or perhaps a supplement, and you're, well, golden.

So before your next beach day, here's what you should know about vitamin D, sunshine, your skin and your health.

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