Vitamin D Supplementation Slows Cellular Aging
Vitamin D supplements slow telomere shortening, reducing biological aging by about three years in older adults.
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Our DNA has built-in protection; however, it wears down with age.
A new study from researchers at Mass General Brigham and Augusta University found that vitamin D supplements may help slow a key marker of cellular aging.
The study was published in The American Journal of Clinical Nutrition.
Vitamin D and telomeres
As we age, the telomeres that help protect our DNA from damage gradually get shorter. Once they wear down too far, cells stop dividing or die. This shortening is linked to a higher risk of diseases like cancer, heart disease and autoimmune conditions.
Researchers have explored how to slow telomere loss as a method for slowing biological aging.
One area of research interest is vitamin D. Several studies have found that people with higher vitamin D levels tend to have longer telomeres, however, these were mostly observational. A few small trials of vitamin D or omega-3 supplements showed some effect, but the findings were inconsistent and often too short to reveal anything about long-term aging.
To address this, researchers launched the VITAL trial – a large, long-term randomized study testing the effects of daily vitamin D3 and omega-3 supplements in older adults. The trial had already shown that vitamin D helps reduce inflammation and may lower the risk of advanced cancer and autoimmune disease, however, the team wanted to see if it also helps maintain telomeres over time.
Measuring aging at the cellular level
The sub-study followed 1,054 adults over 4 years. All participants were at least 50 years old (male) or 55 years old (female) and were generally healthy at the start of the research.
Participants were randomly assigned to take either 2,000 IU of vitamin D3 per day, 1 g of marine omega-3s, both or a placebo. Blood samples were collected at the start, and again at year two and year four. Researchers measured telomere length in white blood cells, a marker of biological aging, using a standard method called qPCR.
Participants taking vitamin D lost less telomere length – around 140 base pairs less than those on placebo. This roughly equates to three fewer years of biological aging.
“Vitamin D3 supplementation reduced telomere attrition and preserved telomere length, supporting an anti-cellular aging effect of vitamin D,” said the authors.
On average, the rate of loss was 0.035 kilobases slower per year in the vitamin D group.
Omega-3s, however, had no measurable effect.
Some groups seemed to benefit more from vitamin D, including people under 64, non-smokers, those with lower BMI and those not on cholesterol-lowering medication.
The anti-aging potential of vitamin D
“VITAL is the first large-scale and long-term randomized trial to show that vitamin D supplements protect telomeres and preserve telomere length,” said co-author Dr. JoAnn Manson, an endocrinologist, epidemiologist and principal investigator of several research studies at Brigham and Women’s Hospital.
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The results suggest potential biological mechanisms for vitamin D’s protective effects. The vitamin may increase telomerase activity, the enzyme that helps rebuild telomeres. It could also protect DNA from oxidative damage or help regulate inflammation through pathways like PI3K/Akt and NF-κB. These are still theories, however, they’re consistent with what has been observed in lab and clinical studies so far.
PI3K/Akt
A cell signaling pathway that helps regulate growth, survival and metabolism. It's involved in how cells respond to damage or stress and may influence telomere maintenance.
NF-κB
A protein complex that plays a key role in controlling inflammation and immune response. It's often activated in chronic diseases and aging.
“Our findings suggest that targeted vitamin D supplementation may be a promising strategy to counter a biological aging process, although further research is warranted,” said lead author Dr. Haidong Zhu, a molecular geneticist at Augusta University.
Larger and more diverse trials are needed, especially to see if slowing telomere loss leads to better long-term health outcomes.
Reference: Zhu H, Manson JE, Cook NR, et al. Vitamin D3 and marine omega-3 fatty acids supplementation and leukocyte telomere length: 4-year findings from the vital randomized controlled trial. Am J Clin Nutrit. 2025. doi: 10.1016/j.ajcnut.2025.05.003
This article is a rework of a press release issued by Mass General Brigham. Material has been edited for length and content.
