Early Exposure is Necessary for the Lifespan Extension Effects of Cocoa in C. elegans

Background: We previously showed that cocoa, a rich source of polyphenols improved the age-associated health and extended the lifespan in C. elegans when supplemented starting from L1 stage. Aim: In this study, we aimed to find out the effects of timing of cocoa exposure on longevity improving effects and the mechanisms and pathways involved in lifespan extension in C. elegans. Methods: The standard E. coli OP50 diet of wild type C. elegans was supplemented with cocoa powder starting from different larval stages (L1, L2, L3, and L4) till the death, from L1 to adult day 1 and from adult day 1 till the death. For mechanistic studies, different mutant strains of C. elegans were supplemented with cocoa starting from L1 stage till the death. Survival curves were plotted, and mean lifespan was reported. Results: Cocoa exposure starting from L1 stage till the death and till adult day 1 significantly extended the lifespan of worms. However, cocoa supplementation at other larval stages as well as at adulthood could not extend the lifespan, instead the lifespan was significantly reduced. Cocoa could not extend the lifespan of daf-16, daf-2, sir-2.1, and clk-1 mutants. Conclusion: Early-start supplementation is essential for cocoa-mediated lifespan extension which is dependent on insulin/IGF-1 signaling pathway and mitochondrial respiration.