A recent study published in the American Journal of Clinical Nutrition claims to prove that if older people take 2000 IU of vitamin D3 supplement daily it will reduce the age-related shortening of their DNA telomeres and thereby could lead to a “three-year decrease in aging.” The present author’s reanalysis of the study, however, reveals that telomere shortening did not reliably differ between the supplementary vitamin D3 treatment group and the placebo control group after two years or even four years of treatment. Vitamin D supplementation is widely recommended for maintaining bone health but the claim that it can slow down aging is baseless.