Vitamin D is a fat-soluble vitamin that is manufactured in the body when sunlight hits the skin. You can also get vitamin D from your diet. Because the vitamin is in so few foods and sunscreen can block your skin from absorbing ultraviolet sun rays, a majority of kids and adults in the United States are believed to be deficient in the sunshine vitamin, according to Scientific American.
Symptoms
The most common symptom of vitamin D deficiency in children is rickets and in adults is osteomalacia, both of which cause softening of the bones and bone pain. According to the Vitamin D Council, other symptoms include chronic pain and depression. The vitamin has also been linked to a number of different conditions ranging from a high incidence of cesarean sections in pregnant women to decreased risk of multiple sclerosis in people who take vitamin D supplements.
Knee Pain
In 2004, experts linked vitamin D deficiency to knee pain, disability and osteoarthritis. In a study that lasted 30 months, researchers from Boston University studied 221 seniors with osteoarthritis of the knee. They found that patients with low blood levels of vitamin D reported significantly more pain compared to patients with high blood levels. The patients who had lower vitamin levels were also significantly more disabled. When given vitamin D supplements, disability scores improved, but pain and weakness scores did not.
Considerations
While vitamin D supplements may reduce disability, subsequent studies show that getting your recommended daily allowance won't necessarily halt the progression of joint disease. In 2007, the journal "Arthritis and Rheumatism" published a study indicating that vitamin D status does not affect cartilage loss in the knee associated with osteoarthritis. These results are based on data concerning roughly 1,000 patients with the degenerative joint disease.
Recommendations
The recommended daily allowance of vitamin D in children and adults is 15mcg, or 600 international units, IU, daily. Seniors, who are at higher risk for developing vitamin D deficiency because their skin is less efficient at converting sunshine, need 20mcg, or 800 IU daily, starting at age 71. Vitamin D toxicity, which is rare but can occur after taking mega doses of the vitamin over a long period of time, can result in loss of appetite, weakness and heart irregularities. In two cases that have been reported, both were a result of taking more than 1,000mcg, or 40,000 IU a day.
References
- "Scientific American"; Vitamin D Deficiency Soars in the U.S.; Jordan Lite; March 2009
- Vitamin D Council; What is vitamin D deficiency?; June 2011
- CNN.com; Vitamin D may lower MS risk; Amy Burkholder; December 2006
- Medscape Medical News; Vitamin D Deficiency Increases Pain of Knee Osteoarthritis; December 2004
- "Arthritis and Rheumatism"; Low Levels of Vitamin D and Worsening of Knee Osteoarthritis; D.T. Felson, et al.; January 2007
- Yale Medical Group: Among the Missing: Vitamin D
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