Over 50s use of vit D supplements shown to protect telomere length and slow biological ageing, major trial finds

Vitamin D supplementation has been found to preserve telomere length and may slow the biological ageing process, according to new findings from the VITAL randomised controlled trial. The results are based on a sub-study co-led by researchers at Mass General Brigham and the Medical College of Georgia.

Telomeres are repetitive DNA sequences located at the ends of chromosomes that protect genetic material from degradation. These structures naturally shorten with age, a process associated with the development of age-related diseases, including cancer and autoimmune disorders.

The VITAL trial is the first large-scale, long-term randomised trial to demonstrate a protective effect of vitamin D supplements on telomere length. “VITAL is the first large-scale and long-term randomised trial to show that vitamin D supplements protect telomeres and preserve telomere length,” said Dr JoAnn Manson, co-author of the study and principal investigator of VITAL. Dr Manson is Chief of the Division of Preventive Medicine at Brigham and Women’s Hospital, a founding institution of the Mass General Brigham healthcare system.

“This is of particular interest because VITAL had also shown benefits of vitamin D in reducing inflammation and lowering risks of selected chronic diseases of ageing, such as advanced cancer and autoimmune disease,” Dr Manson added.

The sub-study, known as the VITAL Telomere Study, assessed 1,054 participants from the original trial cohort. The VITAL trial included 25,871 participants — US women aged 55 and older and men aged 50 and older — who were followed over a five-year period. Participants were randomly assigned to receive either vitamin D3 (2,000 IU per day), omega-3 fatty acids (1 g per day), both supplements, or placebo.

Telomere length in white blood cells was measured at baseline, and again at two and four years into the study. Researchers found that individuals who received vitamin D3 supplementation experienced significantly less telomere shortening over four years compared with those who received placebo—equivalent to nearly three fewer years of biological ageing. Omega-3 fatty acid supplementation, however, had no significant impact on telomere length.

“Our findings suggest that targeted vitamin D supplementation may be a promising strategy to counter a biological ageing process, although further research is warranted,” said Dr Haidong Zhu, lead author of the report and molecular geneticist at the Medical College of Georgia, Augusta University.

While earlier, smaller-scale studies had suggested a potential link between vitamin D and telomere maintenance, results have been inconsistent. The robust design and duration of the VITAL trial now offer the strongest evidence to date of vitamin D’s potential role in preserving cellular health with age.

For further reading please visit:

• 10.1016/j.ajcnut.2025.05.003 

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