A meta-analysis of seven clinical studies found curcumin supplementation lowered serum aminotransferases in people with MASLD. The mechanistic work came from high-fat-diet rats. Curcumin reduced hepatic lipid accumulation, but the benefit weakened in antibiotic-treated rats and transferred through fecal transplantation. Curcumin suppressed Clostridium sensu stricto 1, lowering hepatic kynurenine, which activates AHR, raises H3K27ac at Cebpb, and drives PI3K-AKT signaling and lipid buildup.
The human signal here is modest and the mechanism is entirely animal-derived, so readers should treat this as hypothesis-generating rather than practice-changing. Falling ALT and AST are surrogate markers; the meta-analysis summary offers no data on liver fat by imaging, fibrosis, or hard outcomes, and curcumin trials are notoriously heterogeneous in formulation, dose, and bioavailability. The rodent chain is unusually complete: microbiota depletion, fecal transplant, taxon reconstitution, metabolite add-back and CEBPB knockdown each test causality. Still, the identification of a single Clostridium taxon and kynurenine as the culprit may not translate, since human gut ecology differs, and rat doses are rarely achievable with oral curcumin. The gut-liver-epigenetic framing is the real novelty, adding to evidence that polyphenols act partly through microbial remodeling. For adults with fatty liver, weight loss, exercise and diet quality remain the proven levers; curcumin is at best an adjunct to discuss with a clinician, particularly given rare reports of curcumin-linked liver injury with high-bioavailability products. Incremental.