Does a low vitamin D arthritis link exist? Should you take Vitamin D to help your arthritis? Given the recent popularity of Vitamin D3, it’s surprising that the research is all over the map. Some studies show that low vitamin D is associated with more arthritis and other studies show no association between Vitamin D and arthritis. The first study mentioned is a snapshot association type affair, where researchers look to see if patients with low Vitamin D levels have more arthritis. The second study is a treatment study where researchers gave patients Vitamin D to try and help arthritis pain. Now a new study weighs in that again throws another monkey wrench into this debate.
This new study was longitudinal, in that it followed patients for 5 years who had a moderate Vitamin D deficiency. So it didn’t rely on a snapshot association (i.e. low Vitamin D patients have more arthritis), instead it checked to see if arthritis pain was developing in patients who had low Vitamin D. What did it show? Moderate Vitamin D deficiency is associated with the development of knee and hip arthritis pain over several years. Confused? You should be. How can we make sense of the study that showed that taking Vitamin D didn’t work in light of this new study?
Both the old study and the new one looked at patients who were 62 years old and included a large number of participants. However, that’s where the similarities end. The old study looked at patients with moderately severe arthritis and pain and tried to determine if taking Vitamin D as a sole intervention might reduce that significant pain. The newer study looked at patients who didn’t have much pain and then observed whether the patients with a low Vitamin D developed pain over time (they did). When two studies seek to study the same thing but use different starting groups of patients and arrive at different conclusions, this is sometimes called “Sampling Bias”.
The upshot? If you have moderate to severe arthritis and a low Vitamin D level, popping Vitamin D pills is unlikely by itself to get rid of your pain. However, if you’re trying to prevent arthritis, Vitamin D may be a good selection for many patients. What do you do if you already have arthritis? Vitamin D is not a bad choice when combined with other supplement based strategies. We tested a whole suite of supplements against stem cells to chose which ones we thought were most effective for our supplement. However, don’t expect Vitamin D pills to end your arthritis pain; doing that may take more intervention using other tools.