When the study ended, the group taking supplements had higher vitamin D levels than the placebo group, but “we found really no significant differences in any [OA-related] outcomes between the two groups,” Dr. McAlindon says.

He says that for now, these results should only be applied to people who represent the study sample, as more research is needed to confirm the findings. And he points out that supplemental vitamin D has other benefits, such as improving bone health.

“The osteoporosis physicians are recommending vitamin D. So if people take vitamin D for that reason, nothing needs to change,” Dr. McAlindon says. “If they are taking it for osteoarthritis, they should probably talk to their doctors.”

Katherine Temprano, MD, is an assistant professor of internal medicine in the division of rheumatology at Saint Louis University. She says you could argue, given this study’s limited sample, that more research is needed to look at males and different ethnicities. But she also says this is a very well done and important study.

“There was a definite need to do this. There have been multiple studies that have found a low serum level of vitamin D has been associated with OA, particularly of the knee but other joints too,” Dr. Temprano says. “So you would think that if you took more vitamin D that you might be able to inhibit the disease progression. That had not really been effectively looked at before.”

Still, she recommends people taking vitamin D continue to do so because, as a rheumatologist, she’s always concerned about bone quality.

“We know that for osteoporosis and osteopenia that you do need adequate vitamin D supplementation,” Dr. Temprano says. “So it doesn’t mean you shouldn’t take your vitamin D supplements by any means. It’s just that osteoarthritis is a separate disease and so it may not be the treatment or cure-all for OA, but it still has many other roles for bone health.”