A study by researchers at Mass General Brigham has found that taking a daily multivitamin can slow biological aging in older adults. The study compared blood samples from 958 participants with an average chronological age of 70 and compared them to groups who took a placebo for two years. The vitamin group had a significant slowing in the two clocks that predict mortality, and their aging slowed by about four months on five measures of biological aging. The benefits were greater for those who were biologically older than their chronological age at the start of the trial. The researchers plan to further investigate the effects of this type of aging and other benefits such as cognitive improvements and reductions in cancer and cataracts.