By Louise Gagnon
TORONTO, CANADA -- June 5, 2007 -- Decreased vitamin D levels are linked to shorter telomeres, the end pieces of DNA, according to a study presented here at the 89th annual meeting of the Endocrine Society (ENDO).
The study used data from the TwinsUK cohort to assess if there was a relationship between vitamin D levels and length of telomeres, said lead investigator John Brent Richards, MD, MSc, postdoctoral fellow, King's College, London, United Kingdom.
Dr. Richards noted that telomeres shorten in length with each cell cycle and have been demonstrated to degrade when exposed to inflammation. He explained that vitamin D is thought to inhibit a pro-inflammatory response.
"We can think of the telomeres as having a biological clock that is ticking," explained Richards. "We know that factors such as smoking can affect telomere length."
A total of 2,111 women participated in the study. Their mean age was 49.1 years, with the range being 18 to 80. Investigators measured leukocyte terminal restriction fragment length (TRFL), a measure of the length of telomeres, using the Southern blot method. They also measured 25-OH-vitamin D and C-reactive protein (CRP), an inflammatory marker. Researchers gathered data on subjects' body mass index, age, physical activity level, and smoking status.
Investigators found the difference in TRFL between the highest and lowest tertiles of vitamin D was 92.6 base pairs (P =.006). That result was equivalent to 4.2 years of telomeric aging. They also examined the relationship between TRFL and vitamin D, when stratified by a CRP level of 2.0 mg/l. Moreover, researchers found twins discordant for vitamin D levels were discordant as well for TRFL.
"What we have seen is an association," said Dr. Richards. "We can't say if vitamin D is causing this."
Because vitamin D supplementation is safe and make play a role in modulating telomere length, future research may explore the effect of vitamin D supplementation on telomeres, said Dr. Richards."It would be less of a challenge to provide vitamin D supplementation than to get patients to stop smoking to have a positive effect on telomeres," he added.
The study was funded by several sources including the Wellcome Trust in the UK, the National Institutes of Health in the U.S., the Healthcare Foundation of New Jersey in the U.S., the Canadian Institutes of Health Research in Canada, and GenomEUtwin.
[Presentation title: Serum Vitamin D Levels and Leukocyte Telomere Length in Women. Abstract OR33-2]
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