Higher vitamin D levels linked to reduced telomere shortening

The November, 2007 issue of the American Journal of Clinical Nutrition published an article describing the discovery of British and American researchers of an association between longer telomeres and increased levels of vitamin D. Telomeres are caps on the ends of chromosomes which have been found to shorten with age, as well as with increased oxidative stress and inflammation. The finding suggests that vitamin D may play a role in slowing the onset of age-related diseases.

Dr J. Brent Richards at King's College, London School of Medicine and colleagues studied 2,160 female twins aged 19 to 79 for the current research. Blood samples were analyzed for serum vitamin D levels, C-reactive protein (CRP, a marker of inflammation) and additional factors, and telomere length was measured in the DNA of peripheral white blood cells (leukocytes).

As expected, older participants had shorter telomeres; however, leukocyte telomere length (LTL) was greater among subjects whose levels of vitamin D were high compared to those with low concentrations, a finding which persisted after adjustment for age and other factors. Participants in the top one-third of serum vitamin D levels had telomeres that averaged 107 base pairs longer than those in the lowest third, equivalent to a five year difference in chronologic aging.

Telomere length was also greater in those with lower C-reactive protein levels than in subjects with higher concentrations. When participants who had the highest CRP and lowest vitamin D concentrations were compared with those who had the lowest CRP and highest vitamin D levels, the difference in telomere length was equivalent to 7.6 years of aging.

In a subset analysis of vitamin D supplement users, those who supplemented were also found to have longer telomeres than those who did not supplement with the vitamin.

In their discussion concerning mechanisms of action, the authors note that inflammation and oxidative stress are key determinants in the biology of aging, and that vitamin D decreases mediators of systemic inflammation such as interleukin-2 and tumor necrosis factor-alpha. While habits that increase oxidative stress and inflammation may be difficult to change, they observe that “vitamin D concentrations are easily modifiable through nutritional supplementation or sunshine exposure.”

“Although both LTL and serum vitamin D concentrations decrease with age and are thus possible markers of aging in general, we have shown that the positive association between LTL and vitamin D concentrations is independent of age and many other covariates,” the authors conclude. “Longitudinal studies or randomized controlled trials of supplementation exploring the effect of vitamin D on LTL will be necessary to unequivocally establish the relation between vitamin D and leukocyte telomere dynamics; but for the moment, our data suggest another potential benefit of vitamin D—on the aging process and age-related disease.”