Earlier studies suggested that people with joint disorder having high levels of vitamin-D in their blood will tend to have slower progression of symptoms. But it was not clear if consuming vitamin-D supplements will also have a protective effect or not.
Timothy McAlindon from Tufts Medical Center, Boston led the new study. The team randomly assigned 156 patients having knee osteoarthritis to consume a daily dosage of vitamin-D or vitamin-free placebo for two years while they were not aware of the type of supplement they were assigned to.
The vitamin-D dosage was commenced from 2,000 IU per day and increased gradually to 8,000 IU per day in some patients. The group administered vitamin-D started off slightly worse off then their comparisons with respect to measures of knee pain or function, but the vitamin did not seem to give any clear relief.
On a 0-20 point scale for pain, people taking vitamin-D experienced a reduction in pain by almost 2.3 points during the two years as compared to 1.5 points among those taking placebo. The results observed with respect to changes in knee cartilage volume which in turn is a measure of the progression of osteoarthritis and knee-function were also similar between the two groups both during and after the study period.
Robert Heaney from Creighton University School of Medicine, Omaha, Nebraska said that the effects of vitamin-D differ from one patient to another. While it may be beneficial for some, it might not make any difference to others. Doctors are not clear if genetic or other factors are responsible for this difference in its effects.
While there are no tests available for knowing the effect that vitamin may have on the patient, Heaney said that it is still worth trying these supplements since they may have other small health benefits. McAlindon disagreed though stating that while it is possible that high vitamin-D levels in the blood could help in alleviating knee pain, the results observed so far do not support the idea. He said that vitamin-D is the vitamin of the moment and there are hopes that it will provide wide range of health benefits.