Longevity Briefs: Can Vitamin D Slow Ageing?

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

The problem:

Telomere shortening is thought to be an important driver of ageing. Telomeres are the protective caps located at the ends of our chromosomes, and they help protect our DNA from damage. Every time a cell divides, the chromosomes have to shorten, so telomeres act as ‘sacrificial’ genetic material to prevent important genetic code from being lost. When they become critically short, cells can no longer divide and enter a state called senescence or self-destruct (apoptosis). Shorter telomeres have been linked to an increased risk of chronic diseases, including cancer and cardiovascular disease, as well as to overall mortality. Furthermore, species that display minimal signs of ageing tend to also experience less telomere shortening.

Could artificially extending telomeres in humans prevent age-related diseases and extend lifespan? We don’t know, but clinical trials to investigate the answer to that question are underway. Observational studies have found certain healthy lifestyle practices to be associated with less telomere shortening. Here, researchers ask whether people who take vitamin D supplements experience telomere shortening at a reduced rate.

The discovery:

Researchers looked at data from the VITamin D and OmegA-3 TriaL (VITAL), a large study involving 25,871 participants, who were all 55+ year-old women or 50+ year-old men from the United States. Participants were randomly assigned 2,000 IU/day of vitamin D3, 1g/day of marine omega-3 fatty acids, both, or placebos for five years. Neither the participants nor the people administering the supplements knew who were receiving the real supplements and who were receiving a placebo.

A subgroup of 1031 participants then had their white blood cell telomere length measured at three time points: at the beginning of the study (baseline), after two years, and after four years. Researchers found that vitamin D3 supplementation (2,000 IU/day) was associated with a significant reduction in telomere shortening over the four-year period. Compared to the placebo group, those taking vitamin D3 experienced 0.14 kilobase pairs (kb) or 140 base pairs (bp) less telomere shortening. Over the course of the 4 years, the placebo group’s white cell telomere length decreased by an average of 170 bps, so vitamin D3 appeared to prevent a substantial proportion of the expected shortening. Marine omega-3 fatty acid supplementation, on the other hand, showed no significant effect on telomere length.

The implications:

The effects of vitamin D3 supplementation reported here translates roughly to a 3-year decrease in telomere shortening. This suggests that vitamin D3 supplementation might be able to counteract some telomere attrition and possibly prevent the negative consequences associated with it.

As this study was a trial in which participants were randomly assigned vitamin D3 or placebo, we can be reasonably confident that the vitamin D3 caused a reduction in telomere attrition. What is less certain is the extent to which slower telomere shortening actually benefits human health. Animal studies suggest that interventions that extend telomeres do delay age-related diseases and extend lifespan, but this isn’t well established in humans. Vitamin D has proven anti-inflammatory and anti-proliferative effects (it slows down cell division), which would be expected to delay ageing and preserve telomere length.