December 17, 2009
USA: Vitamin D - Are You Getting Enough?
. NEW YORK, NY / WebMD / Healthy Eating & Diet / December 17, 2009 Vitamin D Deficiency If you shun the sun, suffer from milk allergies, or adhere to a strict vegetarian diet, you may be at risk for vitamin D deficiency. Picture: Getty Images/WebMD/Metabolism Known as the sunshine vitamin, vitamin D is produced by the body in response to sunlight. It is also occurs naturally in a few foods -- including fish, fish liver oils, and egg yolks -- and in fortified dairy and grain products. Vitamin D is essential for strong bones because it helps the body use calcium from the diet. Traditionally, vitamin D deficiency has been associated with rickets, a disease in which the bone tissue doesn't properly mineralize, leading to soft bones and skeletal deformities. But increasingly, research is revealing the importance of vitamin D in protecting against a host of health problems. Symptoms and Health Risks of Vitamin D Deficiency Symptoms of bone pain and muscle weakness can mean you have a vitamin D deficiency. However, for many people, the symptoms are subtle. Yet even without symptoms, too little vitamin D can pose health risks. Low blood levels of the vitamin have been associated with the following: * Increased risk of death from cardiovascular disease * Cognitive impairment in older adults * Severe asthma in children * Cancer Research suggests that vitamin D could play a role in the prevention and treatment of a number of different conditions, including type1 and type 2 diabetes, hypertension, glucose intolerance, and multiple sclerosis. Causes of Vitamin D Deficiency Vitamin D deficiency can occur for a number of reasons: You don't consume the recommended levels of the vitamin over time. This is likely if you follow a strict vegetarian diet, because most of the natural sources are animal-based, including fish and fish oils, egg yolks, cheese, and beef liver. Your exposure to sunlight is limited. Because the body makes vitamin D when your skin is exposed to sunlight, you may be at risk of deficiency if you are homebound, live in northern latitudes, wear long robes or head coverings for religious reasons, or have an occupation that prevents sun exposure. You have dark skin. The pigment melanin reduces the skin's ability to make vitamin D in response to sunlight exposure. Some studies show that older adults with darker skin are at high risk of vitamin D deficiency. Your kidneys cannot convert vitamin D to its active form. As people age their kidneys are less able to convert vitamin D to its active form, thus increasing their risk of vitamin D deficiency. Your digestive tract cannot adequately absorb vitamin D. Certain medical problems, including Crohn's disease, cystic fibrosis, and celiac disease, can affect your intestine's ability to absorb vitamin D from the food you eat. You are obese. Vitamin D is extracted from the blood by fat cells, altering its release into the circulation. People with a body mass index of 30 or greater often have low blood levels of vitamin D. DIET SLIDE SHOWS Whether you want to lose weight, boost your energy level, or eat for better health, find practical tips to help you reach your goals. * 12 Diet Mistakes to Avoid * Best and Worst Juices * Energy Foods * The High-Protein Diet * Becoming a Vegetarian * Salt Shockers Tests for Vitamin D Deficiency The most accurate way to measure how much vitamin D is in your body is the 25-hydroxy vitamin D test. In the kidney, 25-hydroxy vitamin D changes into an active form of the vitamin. The active form of the vitamin can be measured through the blood. The active form of vitamin D helps control calcium and phosphate levels in the body. The normal range is 30.0 to 74.0 nanograms per milliliter (ng/mL). A lower level indicates vitamin D deficiency, which you should discuss with your doctor. Treatment for Vitamin D Deficiency Treatment for vitamin D deficiency involves getting more vitamin D -- through diet, supplements, and/or through spending more time in the sun. Although there is no consensus on vitamin D levels required for optimal health -- and it likely differs depending on age and health conditions -- a concentration of less than 20 nanograms per milliliter is generally considered inadequate, requiring treatment. Similarly, evidence is lacking to establish a recommended dietary allowance (RDA) for vitamin D. However, the Food and Nutrition Board at the Institute of Medicine of the National Academies has established an adequate intake (AI), a reference value established when evidence is insufficient to develop an RDA; it is set at a level assumed to ensure nutritional adequacy. The AI for children and men and women up to age 50 is 5 micrograms (mcg) or 200 international units (IU); 10 mcg (400 IU) between ages 51 and 70; and 15 mcg (600 IU) after age 70. If you don't spend much time in the sun or always are careful to cover your skin ( sunscreen inhibits vitamin D production), you should speak to your doctor about taking a vitamin D supplement, particularly if you have risk factors for vitamin D deficiency. [rc] Reviewed by Gary D. Vogin, MD © 2009 WebMD, LLC