Chromosomes, which house the DNA instructions for building cells, have protective strings attached to them, called telomeres, which shorten with age leading to less accurate cell replacement. Telomere length is a marker of biological aging. Shorter telomeres have been linked with higher mortality within a given period of time and an increased risk of some chronic diseases. This study evaluated 586 participants, 65% percent of which were using multivitamin supplements at least once per month, three quarters of which consumed them daily. 89% of all multivitamin users consumed one a day multivitamin formulas, 21% consumed antioxidant combinations, and 17% were users of "stress-tabs" or B complex vitamins. The researchers found 5.1% longer telomeres on average in daily users of multivitamins compared with nonusers. Increased telomere length was associated with one a day and antioxidant formula use, but not with stress-tabs or B complex. Individual vitamin B12 supplements were associated with increased telomere length and iron supplements with shorter telomeres. When nutrients from food were analyzed, vitamins C and E emerged as protective against telomere loss. In their discussion of the findings, the authors explain that telomeres are particularly vulnerable to oxidative stress. Additionally, inflammation induces oxidative stress and lowers the activity of telomerase, the enzyme that that is responsible for maintaining telomeres. Because dietary antioxidants, B vitamins, and specific minerals can help reduce oxidative stress and inflammation, they may be useful for the maintenance of telomere length. In fact, vitamins C and E have been shown in cell cultures to retard telomere shortening and increase cellular life span. "Our study provides preliminary evidence linking multivitamin use to longer leukocyte telomeres," the authors conclude. "This finding should be further evaluated in future epidemiologic studies and its implications concerning aging the etiology of chronic diseases should be carefully evaluated." The study was reported online in the March issue of the American Journal of Clinical Nutrition .