Vitamin D supplements may protect telomeres and slow ageing

Vitamin D supplements may help safeguard the caps on our chromosomes that influence ageing, raising the prospect that the sunshine vitamin could support better health for longer, according to a recent study.

Researchers found that a daily dose of 2,000 IU (international units, a standard measurement for vitamins) of vitamin D helped preserve telomeres. These tiny structures resemble the plastic tips on shoelaces, shielding our DNA from harm whenever cells divide.

Located at the ends of each of our 46 chromosomes, telomeres become shorter each time a cell replicates. Once they are too short, cells can no longer divide and ultimately die.

Scientists have associated shorter telomeres with several of the diseases we most fear in later life, including cancer, heart disease and osteoarthritis. Smoking, long-term stress and depression all seem to accelerate telomere shortening, while inflammation within the body also causes damage.

Beyond strong bones

Vitamin D's importance for bone health is well established: it enables the body to absorb calcium. Children, teenagers, and people with darker skin or little exposure to sunlight especially need sufficient levels to develop and retain strong bones.

Vitamin D also supports the immune system. One review of the evidence concluded that vitamin D supplements can reduce respiratory infections, particularly among people who are deficient.

Preliminary research has even indicated that it could help to prevent autoimmune conditions such as rheumatoid arthritis, lupus and multiple sclerosis, although further trials are required.

Because inflammation harms telomeres, vitamin D's anti-inflammatory properties may account for its protective effect.

Vitamin D and telomere protection

In the recent study, conducted at Augusta University in the US, researchers tracked 1,031 participants with an average age of 65 over five years. They measured telomeres at the outset, after two years and again after four years. One half of the group took 2,000 IU of vitamin D each day, while the remaining half were given a placebo.

The findings showed that telomeres in the vitamin D group were preserved by 140 base pairs compared with the placebo group. For perspective, earlier research has shown that telomeres naturally lose around 460 base pairs over a decade, which suggests that vitamin D's protective effect may be genuinely significant.

This is not the first encouraging result. Previous studies have identified comparable benefits, and the Mediterranean diet, which is rich in anti-inflammatory nutrients, has likewise been associated with longer telomeres.

The catch

However, several important caveats remain. Some scientists caution that exceptionally long telomeres could themselves raise the risk of disease, indicating that there may be an ideal range that is not yet understood.

There is also no consensus about the appropriate dose. The Augusta researchers gave participants 2,000 IU a day, substantially more than the currently recommended intake of 600 IU for people under 70 and 800 IU for older adults. However, other studies suggest that as little as 400 IU could help to prevent colds.

Experts say that the best dosage is likely to vary according to individual circumstances, including existing vitamin D levels, general nutrition and the way the vitamin interacts with other nutrients.

Healthy ageing beyond supplements

Despite the excitement around these findings, it is premature to begin taking high-dose vitamin D in the hope of slowing ageing. The most robust evidence for healthy ageing still supports the fundamentals: a balanced diet, regular exercise, good-quality sleep, avoiding smoking and controlling stress. All of these habits naturally promote telomere health.

Nevertheless, supplements are still a sensible option, supported by decades of research, for those who are vitamin D deficient or at risk of poor bone health.

As researchers continue to unravel the mysteries of ageing, vitamin D's contribution to keeping our cellular clocks running may turn out to be only one part of a far bigger puzzle.

Dervla Kelly, Associate Professor, Pharmacology, University of Limerick

This article is republished from The Conversation under a Creative Commons licence. Read the original article.