Dont look to vitamin D pills to relieve your knee arthritis pain. Contradicting prior observational studies, a new Tufts randomized trial found no significant difference between vitamin D supplements and placebo among 146 patients with severe osteoarthritis of the knee. The two-year trial measured pain and also used MRI scans to assess loss of cartilage. Pa-tients were randomly assigned to a placebo or an initial dose of 2,000 IU daily of vitamin D, with higher amounts if necessary to achieve blood levels of more than 36 ng/mL. Timothy E. McAlindon, MD, MPH, chief of rheumatology at Tufts Medical Center, and colleagues published their results in JAMA. They noted that hopes vitamin D might benefit arthritis patients were based on its role in bone health; observational studies had hinted at slower disease progression among patients with higher vitamin D levels.