Vitamin D Deficiency
Vitamin D Deficiency
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
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.
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.
Guidelines from the Institute of Medicine call for increasing the recommended dietary allowance (RDA) of vitamin D to 600 international units (IU) for everyone aged 1-70, and raising it to 800 IU for adults older than 70 to optimize bone health.
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.
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National Library of Medicine, National Institutes of Health, MedlinePlus: "25-hydroxy Vitamin D