Thanks to our obsession with sunscreen—as well as a short list of vitamin-D-rich foods and hours spent indoors—three out of four Americans don’t get enough vitamin D. While we once thought vitamin-D deficiency was only a problem for people living in northern latitudes, a 2010 Pediatrics study found that 56 percent of teens living in the sunny South were vitamin-D-insufficient, meaning they didn’t soak up enough rays to produce the amount of D required for optimal health. The recommended quota (600 IU daily, 800 if you’re over 71) is critical for strong bones, but many experts say you may need even more to lower risk of heart disease, type 2 diabetes, multiple sclerosis and many kinds of cancer (the upper limit is 4,000 IU).
Healthy Tip: Bare it all…briefly. Michael F. Holick, Ph.D., M.D., director of the vitamin D, skin and bone laboratory at Boston University School of Medicine, recommends everyone get 10 to 15 minutes of sun on their arms and legs (and abdomen and back when possible) sans sunscreen three times a week during spring, summer and fall (when you can get enough UV rays to produce sufficient vitamin D). He also suggests everyone eat D-rich foods (namely wild-caught salmon, which delivers more D than farmed salmon; UV-exposed mushrooms; and fortified dairy and orange juice) and take a supplement of 1,500 to 2,000 IU of vitamin D3 each day.