Anti-obesity and health-promoting effects of shiitake-fermented black rice bran in Caenorhabditis elegans

The global rise in obesity has increased interest in natural anti-obesity agents. Black rice bran, a by-product of rice processing, is rich in polysaccharides and polyphenols, whose bioavailability can be enhanced through fermentation. In this study, we investigated the anti-obesity effects of polysaccharide-rich black rice bran fermented with Shiitake mushroom mycelium, using Caenorhabditis elegans as an in vivo model. The water-soluble fermentation culture supernatant was administered to worms fed a high-fat diet induced by oleic acid, and body fat accumulation was assessed using Oil Red O staining. Supplementation markedly reduced body fat accumulation without causing adverse physiological effects. Moreover, it mitigated age-related motility decline in liquid culture and attenuated the deterioration of intestinal barrier integrity during adulthood. Together, these results demonstrate that the fermented black rice bran supernatant not only suppresses lipid accumulation but also preserves key physiological functions associated with healthspan. These findings suggest that bioprocessed black rice bran is a safe, multifunctional ingredient with anti-obesity and healthy aging potential, highlighting its promise for metabolic health applications and its contribution to a sustainable food system through the valorization of food by-products.