Is vitamin D in rheumatoid arthritis a magic bullet or a mirage? The need to improve the evidence base prior to calls for supplementation.

In this article the authors highlight the lack of evidence base to support the notion that vitamin D supplementation prevents or reduces rheumatoid arthritis (RA) disease activity while emphasizing on the need for large studies in the area. They note that the observational trials linking low circulating 25-hydroxyvitamin D (25[OH]D) levels to RA and other medical conditions are likely to undergo reverse causality and residual confounding.