Arthritis Awareness: Vitamin D may play important role

Getting more vitamin D appears to improve muscle strength and physical function for vitamin D-deficient patients with knee osteoarthritis, say researchers. Previous studies have linked low vitamin D with a greater risk for severity of knee osteoarthritis; however, this is the first look at vitamin levels in relation to pain and disability.

For this study, 221 patients, average age 67 years, were measured for changes in pain, physical function, muscle strength and serum levels of vitamin D two or more times across a 15- and 30-month period. At the outset, the 48% of patients with low levels of vitamin D experienced more pain and disability than those with normal or higher levels.

Researchers also found that those with adequate vitamin D who became deficient over time experienced worsening disability scores, while those with low vitamin D who became sufficient over time improved their disability scores.

Vitamin D, which comes primarily from exposure to sunlight, promotes the absorption of calcium and phosphorus in bone mineralization, growth and repair. Sources of vitamin D are available to a lesser extent from dietary sources typically found in oily fish, liver, fortified breakfast cereals and dairy products. However, the elderly are less efficient at producing vitamin D from sunlight and absorbing it from food. To address their higher risk for D deficiency, the elderly population is often directed to take a vitamin D supplement.

“Data suggests that many people may be vitamin D deficient, especially those living in the northern hemisphere, and darker skinned individuals,” said Kristin Baker, PhD, a researcher from Boston University. “The good news is vitamin D levels are easily modifiable through safe, short-term exposure to sun and/or dietary intake, and may lessen the disability and pain of osteoarthritis.”

American College of Rheumatology. Oct 17, 2004