Semecarpus anacardium, commonly known as the marking nut, has roots in traditional Ayurvedic medicine, where it has long been used for the management of inflammatory disorders, including Rheumatoid Arthritis (RA). Over the past two decades, several preclinical and a limited number of clinical studies have sought to validate these traditional claims.

Scientific evidence indicates that extracts of Semecarpus anacardium possess significant anti-inflammatory and immunomodulatory activities. In animal models of arthritis, such as collagen-induced and Freund’s adjuvant-induced arthritis in rats, administration of various extracts (notably the ethyl acetate fraction) has resulted in reductions in paw edema, pro-inflammatory cytokines (e.g., TNF-α, IL-1β), and markers of oxidative stress. These results are attributed to the presence of bioactive compounds such as bhilawanols and flavonoids.

Limited clinical studies, mostly small open-label trials conducted in India, have reported improvements in symptoms and reductions in inflammatory markers in patients with RA when treated with processed Semecarpus anacardium formulations. However, these studies often lack rigorous design, large sample sizes, or blinding, which limits the strength of the conclusions that can be drawn.

In summary, while there is a strong traditional basis for the use of Semecarpus anacardium in RA, and a moderate amount of scientific evidence from animal studies and preliminary clinical trials, robust, high-quality human evidence is still lacking. The overall quality of evidence supporting its use in RA is moderate (rated 3/5).