Vitamin D No Cure for Knee OA

Another hopeful theory bites the dust! Vitamin D supplements had no impact on the pain of knee osteoarthritis (OA), researchers discovered in a randomized placebo-controlled trial of 146 people with symptomatic knee OA. Vitamin D, the absence of which causes rickets, is essential for bone health. But its connection to OA is, we now know, probably non-existent.

The patients were enrolled at Tufts Medical Center in Boston between March 2006 and June 2009 and randomly assigned to receive oral cholecalciferol or a placebo. The initial dose was 2, 000 IU a day with dose escalation, if necessary, to achieve a serum level of more than 36 ng/ml.

According to Michael Smith, writing in MedPage Today, the primary outcomes of the study were to be knee pain severity, as measured on the Western Ontario and McMaster Universities’ pain scale, and loss of cartilage as measured by MRI.

The results: baseline knee function was significantly worse in the treatment group than in the placebo group. Knee pain decreased in both groups, dropping by an average of 2.31 points in the treatment group and 1.46 in the placebo group, but the differences were not statistically significant. The percentage of cartilage volume fell by 4.3% and 4.25% in the treatment and placebo groups but, again, the difference was not statistically significant. The lead researchers, Timothy McAlindon, D.M. of Tufts, and his colleagues, reported their results in an article in the January 9 issue of the Journal of the American Medical Association.

The authors wrote that the idea that vitamin D might help victims of osteoarthritis was based on its role in bone health, combined with the importance of bone changes in OA and epidemiologic observations that hinted at slower disease progression among patients with higher vitamin D levels. They added that, no medical treatments are presently available that alter the course of the disease.

Smith quoted Joseph Guettler, M.D., of Beaumont Health System in Royal Oak, Michigan, as saying that one of the main limitations of the study was the focus on vitamin D, which is essential for bone health but less so for maintenance of healthy cartilage. “When it comes to articular cartilage, we might have been barking up the wrong tree here, ” Guettler told MedPage Today. “I think future study needs to focus on components of healthy articular cartilage, such as glucosamine-chondroitin [and] hyaluronic acid derivatives that are known to lubricate and nourish healthy joints.”