Time in the sun helps your skin make vitamin D, a fat-soluble vitamin which is essential for the absorption of calcium and for good bone health. Many people in the United States don't get enough vitamin D. "Most places in this country don't provide enough sunlight," says Diane Schneider, MD, author of The Complete Book of Bone Health. "And many people are using sunscreen these days. You're saving your skin, but blocking your ability to make vitamin D." During the summer months, Schneider recommends spending 10 to 15 minutes in the sun every day in short sleeves and shorts and also taking a vitamin D supplement.
Adults under the age of 70 need 600 IUs of vitamin D, while those over 70 require 800 IUs of vitamin D, says the Institute of Medicine. You can also get some vitamin D from vitamin D-fortified milk, egg yolks, and fatty fish like wild salmon, but the amount in food is limited. To find out if you're deficient in vitamin D, ask your doctor for a blood test.