Adults require anywhere from 600 to 800 international units of vitamin D per day, but it's a micronutrient found naturally in few food sources. Fortified foods provide most of the vitamin D in the American diet, according to the Office of Dietary Supplements, and some people can get enough through exposure to sunlight. A vitamin D deficiency is fairly common, but you might mistake its symptoms for another condition – if you experience any symptoms at all.
Prevalence of a Deficiency
According to an article published in "Mayo Clinic Proceedings" in August 2010, vitamin D deficiency is much more prevalent than it has been in the past. Between 1988 and 1994, 60 percent of Caucasian adults had sufficient vitamin D; between 2001 and 2004, this number had dwindled to 30 percent. In black adults, vitamin D sufficiency dropped from 10 percent to 5 percent during the same time span.
You might not realize that you have a vitamin D deficiency, says the Vitamin D Council, as symptoms can be very vague, including fatigue and general aches and pains, if they manifest at all. But certain signs are more common than others -- manifestations of a deficiency can include lower back pain, throbbing bone pain marked by feelings of pressure over the sternum or tibia and muscle weakness. These symptoms sometimes lead to a misdiagnosis of fibromyalgia, chronic fatigue syndrome or arthritis, according to American Family Physician.
If you're experiencing hallmark symptoms of depression, including decreased energy, irritability, loss of interest in activities and persistent sad or anxious feelings, a vitamin D deficiency could be blame. Two studies published in 2013 – one in "Molecular Psychiatry" and another in the "British Journal of Psychiatry" -- linked depression to a low vitamin D level. Both studies, however, noted that further research should be done. If you're feeling symptoms of depression, speak with your health care provider about the best treatment and potential causes.
Testing for a Deficiency
Get to the bottom of your symptoms by asking your doctor for a vitamin D test, known as the 25(OH)D test. Your results will come back measured as nanograms per milliliter. Although the definition of a deficiency varies among organizations, the 2010 "Mayo Clinic Proceedings" article reports that an insufficiency is often categorized as under 30 nanograms per milliliter and a deficiency as less than 20 nanograms per milliliter. The Vitamin D Council recommends a level of 50 nanograms per milliliter. If your results return as insufficient or deficient, speak with your physician about the best course of treatment.
- Mayo Clinic Proceedings: Vitamin D Deficiency in Adults: When to Test and How to Treat
- Vitamin D Council: Testing for Vitamin D
- American Family Physician: Recognition and Management of Vitamin D Deficiency
- Molecular Psychiatry: The Association Between Low Vitamin D and Depressive Disorders
- British Journal of Psychiatry: Vitamin D Deficiency and Depression in Adults: Systematic Review and Meta-Analysis
- Vitamin D Council: Am I Deficient in Vitamin D?
- Office of Dietary Supplements: Vitamin D