The Additive Effects of Curcumin Supplementation in Addition to an Anti‐Inflammatory Diet on Inflammatory Indices in Patients With Hashimoto's Thyroiditis ( <scp>HT</scp> ): A Double Blind Randomized Controlled Clinical Trial

ABSTRACT Hashimoto's thyroiditis (HT) is a chronic autoimmune condition characterized by persistent thyroid inflammation. Patients with HT may benefit from anti‐inflammatory strategies. This study was designed to examine the combined impact of an anti‐inflammatory diet and curcumin supplementation on inflammatory markers in individuals with HT. In this randomized controlled clinical trial, 57 individuals diagnosed with Hashimoto's thyroiditis (HT) in Tehran, Iran, were recruited and randomly allocated to two intervention arms. One group received an anti‐inflammatory diet in conjunction with 1500 mg of curcumin daily, while the other group followed the same diet but was administered a placebo. Inflammatory biomarkers including high‐sensitivity C‐reactive protein (hs‐CRP), interleukin‐6 (IL‐6), and nuclear factor kappa B (NF‐κB) were measured at the start of the study and again following a 12‐week supplementation period to assess the additive effect of curcumin. Curcumin supplementation resulted in a reduction in IL‐6 (−5.28 ± 9.75, p = 0.009). Additionally, it decreased hs‐CRP levels in patients with HT, with a mean reduction of −1.17 ± 5.70 mg/L, whereas the placebo group exhibited an increase of +1.53 ± 3.33 mg/L ( p = 0.305). Also, curcumin supplementation significantly reduced NF‐κB levels in patients with HT (−0.09 ± 0.22 vs. 0.03 ± 0.15, p = 0.019), while the placebo group showed a slight increase (0.65 ± 0.16 to 0.68 ± 0.13). Curcumin, by reducing inflammation, can be effective as an adjunctive treatment alongside an anti‐inflammatory diet in individuals with HT. Additional studies are warranted. Name of the Registry: National Nutrition and Food Technology Research Institute. Trial Registration Number: NCT0597586. Date of Registration: 2023‐08‐04. URL of Trial Registry Record: https://www.clinicaltrials.gov/study/NCT05975866?term = NCT05975866&amp;rank = 1.