The COSMOS trial is a randomized clinical trial that investigated the effects of daily supplementation with a multivitamin-multimineral and cocoa extract. The analysis was in a pre-specified supplementary analysis. Supplementation took place over 2 years. Daily multivitamin-multimineral reduced biological aging as measured by the epigenetic aging clock. Cocoa extract did not have this effect. The study was published in Nature Medicine on March 9, 2026 with doi:10.1038/s41591-026-04239-3.