Low vitamin D levels may cause greater knee pain and difficulty walking in patients who have osteoarthritis of the knee. According to research presented this week at the 2007 American College of Rheumatology Annual Scientific Meeting in Boston, Massachusetts, studies have shown that vitamin D impacts both musculoskeletal and neuromuscular function.
In a 2-year trial of vitamin D supplements and their effect on the progression of knee osteoarthritis, researchers assessed whether vitamin D deficiency at the beginning of the study was tied to osteoarthritis pain and physical function. There were 65 men and 35 women in the study. The study participants, who all showed signs of knee osteoarthritis, were in their 60s. Blood levels of vitamin D, baseline knee pain, time needed to arise from a chair several times, and the time needed to walk 20 meters were compared.
Forty-seven of the 100 participants were were found to be deficient in vitamin D. The deficiency was linked to increased pain and difficulty walking but it did not affect time needed to get up from a chair repeatedly. Vitamin D promotes absorption of calcium and phosphorus required for bone mineralization, growth, and repair. Vitamin D is available from dietary sources, especially fortified foods, and supplements. Sun exposure helps vitamin D become active in the body. Vitamin D supplements have long been recommended, especially for the elderly, and to prevent osteoporosis (vitamin D supplements of 400-800 mg/day along with calcium supplements of 1200-1500 mg/day are recommended). Future results from the ongoing study will help determine if vitamin D is an effective treatment for knee osteoarthritis.
