Z-Astaxanthin exhibits superior anti-obesity effects in Caenorhabditis elegans: insights from geometric isomers and signaling pathways.

Background: Astaxanthin (AST) exists as an 'all-E' isomer and various 'Z' isomers due to its multiple conjugated double bonds. The Z configuration has been reported to exhibit stronger antioxidant activity, raising interest in its potential health benefits. All-E AST is a potent chemopreventive agent for weight loss but the anti-obesity efficacy of Z isomers remains unclear.