Ascophyllum nodosum, a brown seaweed, has gained attention for potential benefits in metabolic disorders, including non-alcoholic fatty liver disease (NAFLD). The scientific rationale primarily centers on its content of bioactive compounds such as polyphenols (notably phlorotannins), fucoidans, and alginates, which have demonstrated antioxidant, anti-inflammatory, and lipid-lowering properties in preclinical models.

Animal studies provide the bulk of evidence: Several rodent models of NAFLD have shown that extracts of Ascophyllum nodosum can reduce hepatic fat accumulation, improve liver enzyme profiles, decrease oxidative stress, and modulate inflammatory cytokines. For example, some studies report that supplementation leads to downregulation of genes involved in lipogenesis and improved insulin sensitivity. There is also evidence that the fiber and polyphenols in A. nodosum may favorably alter gut microbiota, which could indirectly benefit liver health.

However, human clinical data are currently lacking. No large-scale, placebo-controlled trials have directly evaluated Ascophyllum nodosum supplementation for fatty liver disease in humans. Therefore, while the use is scientifically motivated and supported by promising preclinical evidence, the strength of evidence (rated 2/5) remains modest and insufficient for clinical recommendation. Further research, especially human trials, is needed to validate efficacy and safety in this context.