Our bodies need vitamin D to help build bones, to support immune health and keep muscles and brain cells working. Vitamin D supplements also show signs of protection against biological aging. Researchers at Mass General Brigham report vitamin D supplements help maintain telomeres—the protective cap at the end of our chromosomes. Telomeres tend to shorten as we age, but vitamin D supplements protect and preserve. While telomeres and chromosomes may not be in the daily vocabulary of most of us, we all have them and protecting and preserving them should be of highest importance. Authors of the study in the American Journal of Clinical Nutrition suggest targeted, not random, vitamin D supplementation is a promising way to counter a natural aging process.