Vitamin D pills don't reduce arthritis pain or cartilage loss in people diagnosed with osteoarthritis, says a new study.

Osteoarthritis is the most common form of arthritis. The condition causes pain and swelling in the joints, usually hands, knees, hips or spine, according to Medline Plus. Osteoarthritis breaks down cartilage - the slippery tissue that covers the ends of bones in a joint. Loss of cartilage leads to rubbing of the bones in the joint that can cause bone deformity.

"Knee osteoarthritis (OA) is a common age-related musculoskeletal disorder that has significant functional impact and has considerable societal costs through work loss, early retirement, and arthroplasty. Despite its impact, there are no medical treatments established to influence the course of the disease. Some studies have suggested that vitamin D may protect against structural progression," says the new release.

The study included 146 participants with symptomatic knee OA who were enrolled in the study between March 2006 and June 2009. Average age of the participants was 62 years.

Participants were given a placebo or oral cholecalciferol, 2,000 IU/day. The study was conducted over a period of two years.

People who were using vitamin D reported worse pain than people who were on placebo.

In both groups, researchers found that knee pain decreased at almost the same rate. And, cartilage volume decreased by about 4 percent for people on Vitamin D and in those on placebo, meaning there was no significant difference in the groups.

Dr. Robert Heaney, who has conducted research on vitamin D told Reuters Health that the present study's results didn't surprise him.

"It's almost certain that vitamin D's effects are different from person to person. It's very important for some people, but may not make any difference for others," Dr. Heaney, who wasn't a part of the study, told Reuters.

The study is published in the journal JAMA.

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