(BLACK PR WIRE) "" It's summertime, and you're doing your best to protect your skin by staying out of the sun as much as possible and lathering on sunscreen when outside. But could this healthy habit lead to a vitamin D deficiency?

Sun exposure in moderation is the greatest source of vitamin D "" a nutrient crucial to overall health, says Anaisys Ballesteros, D.O., a Baptist Health primary care physician.

Sunlight triggers vitamin D production in the body, which is why it's known as the sunshine vitamin. But a study published by the National Institutes of Health (NIH) reveals that wearing sunscreen with SPF 30 reduces the skin's ability to make vitamin D by more than 95 percent.

Your skin pigment also can be a natural sunscreen. People with dark skin, including African Americans and Hispanics, are at higher risk for vitamin D deficiency because the pigment melanin decreases their skin's ability to produce vitamin D from the sun, the NIH advises.

Someone with very dark skin needs up to 10 times the amount of sun exposure than someone with a very pale complexion to make the same amount of vitamin D. Approximately 40 to 60 percent of African Americans are vitamin D deficient.

"I advise most patients to get around 15 minutes of sun exposure without sunscreen, three to four days a week," Dr. Ballesteros said. "Patients at high risk for skin cancer should get their vitamin D through diet and supplements."

Health Risks Being deficient in vitamin D can pose health risks. The nutrient helps the body absorb, retain and use calcium "" one of bone's main building blocks, says Dr. Ballesteros. Without enough vitamin D, children may be at greater risk for rickets, a softening and weakening of the bones, and adults may be at greater risk for osteoporosis.

Vitamin D deficiency also has been associated with increased risk of autoimmune diseases, hypertension, infectious diseases, muscle weakness, cognitive impairment and some cancers, according to research published in The American Journal of Clinical Nutrition.

D in Your Diet You can get some of the vitamin D you need from your diet. The nutrient occurs naturally in a few foods, including salmon, mackerel, canned tuna, egg yolks, cheese, mushrooms and beef liver "" and in fortified foods such as milk, yogurt, orange juice and breakfast cereals, says the NIH. However, even the best dietary sources of vitamin D do not contain plentiful amounts of the nutrient, and many people simply do not eat enough of these foods.

Other risk factors

The NIH lists the following additional factors that increase your risk of vitamin D deficiency:

"¢ Medical problems, such as Crohn's disease, cystic fibrosis, and celiac disease affect your intestine's ability to absorb vitamin D from the food you eat.

"¢ Being overweight or obese affects the level of vitamin D in your blood because the nutrient is fat soluble, which means it gets diluted.

"¢Advancing age affects your kidneys' ability to convert vitamin D to its active form and your skin's ability to make vitamin D.

Symptoms of Deficiency What should you watch for if you're concerned about your vitamin D level?

"Most people do not have symptoms," said Dr. Ballesteros. "But that does not mean that the deficiency will not compromise your health."

If patients do experience symptoms of vitamin D deficiency, bone pain, muscle weakness and joint stiffness are the most common. Some people also get "the blues." However, these symptoms often are subtle and can be misdiagnosed as fibromyalgia, dysthymia, degenerative joint disease, arthritis, chronic fatigue syndrome and other diseases, according to a study published in The American Journal of Clinical Nutrition.

A simple blood test can accurately measure your vitamin D level.

"I include a vitamin D screening as part of a patient's annual physical," Dr. Ballesteros said. "About 70 percent of my patients have a deficiency."

Take Action If you're concerned you're not getting enough vitamin D through diet and sunlight, talk to your doctor about taking a supplement, especially if you have additional risk factors for vitamin D deficiency.

The Institutes of Medicine recommends most children and adults under age 70 get at least 600 International Units (IU) of vitamin D daily, and those over 70 should aim for at least 800 IUs. Dr. Ballesteros and many doctors believe that people need nearly double this amount for maximum benefit.

"It's also important that people are consistent. You should not stop taking the supplement when your vitamin D level rises," Dr. Ballesteros added. "Supplementation must continue for the proper level to be maintained."