Osteoporosis

Sun's Rays Can Be Beneficial

For many people, the Memorial Day holiday marks the unofficial beginning of summer. Across the Tristate, families host holiday cookouts and neighborhood pools open their gates for kids and sunbathers alike.

But while the sun's rays can be dangerous without proper skin protection, the sun has some benefits, too.

Small doses of sunlight can help trigger vitamin D synthesis in the skin, which is key for aiding in the absorption of calcium for our bones.

What is Vitamin D?

Vitamin D is a fat-soluble vitamin found in some foods and can be made in your body after exposure to ultraviolet rays from the sun. It helps the body maintain normal blood levels of calcium and phosphorus and promotes calcium absorption to help form and maintain strong bones.

Insufficient levels of vitamin D can be dangerous, preventing bone tissue from hardening and even contributing to the development of several types of cancer, heart disease and diabetes.

Take caution to protect your skin from sun damage, but don't avoid sunlight altogether.

But How Much Vitamin D Do You Need?

From birth to age 50, people should get 200 international units (IU) of vitamin D a day. You can get 200 IU, for example, from a can of tuna or two 8-ounce glasses of milk.
Adults ages 51 to 69 require 400 IU daily, and those over 70 require 600 IU.
It is recommended that patients with osteoporosis get at least 800 to 1,000 IU of vitamin D daily.
To get the maximum benefit of vitamin D from the sun's rays, experts recommend 15 minutes of sun per day, three days a week, on the face, neck and arms.

For other people, who get up before sunup and put on sunblock first thing, a supplement of vitamin D is usually required, which are readily available without a prescription.

It's possible to get too much vitamin D. The safe "upper limit" is 2,000 IU daily, but it's impossible to get vitamin D toxicity from sun exposure and toxicity from over-the-counter doses is unlikely.

This article originally appeared in UC Health Line (5/22/2008), a service of the University of Cincinnati Academic Health Center Public Relations Communications Department and was adapted for use on NetWellness with permission, 2006.

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Last Reviewed: May 23, 2008

Nelson Watts, MD, FACP, MACE
Professor of Medicine
Director, Bone Health and Osteoporosis Center
Division of Endocrinology and Metabolism
Department of Internal Medicine
College of Medicine
University of Cincinnati