Study Finds Vitamin D3 Supplementation Reduces Telomere Attrition

Research suggests that maintaining telomere length is crucial for cellular health, and new study findings published in The American Journal of Clinical Nutrition suggest that vitamin D and omega-3 fatty acid (n-3 FA) supplementation might play a beneficial role. However, there is a lack of evidence from large-scale randomized clinical trials that confirm the potential benefit. To address this gap, investigators leveraged data from the VITaminD and OmegA-3 TriaL (VITAL) trial to evaluate whether vitamin D or n-3 FA supplementation can reduce leukocyte telomere length (LTL) attrition over time.¹

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What is the Role of Telomeres?

Telomeres are protective caps of repetitive DNA found at the ends of chromosomes, preventing them from fraying or tangling. With each cell division, telomeres shorten naturally until they reach a critical length, at which point the cell can no longer divide and subsequently dies, according to the National Human Genome Research Institute.²

“At the very end of the telomere is a sort of knot not called the "T-loop," which keeps the chromosome ends from all sticking together. Every time a cell divides, some of those telomere repeats get cut off. So, in certain cell types that divide a lot, an enzyme called "telomerase" adds those repeats back, so the telomere doesn't get too short,” Lisa H. Chadwich, PhD, deputy director of the Division of Genome Sciences, said in a news release.²

Additionally, telomere shortening is thought to contribute to decreased chromosomal stability, elevating the risk of chronic diseases, cancer, cardiovascular disease, and overall mortality. Leukocyte telomere length (LTL) serves as an indicator and reflects the combined influence of genetic, environmental, lifestyle, and nutritional factors throughout an individual’s life. Following, identifying factors that can slow telomere shortening is crucial for potentially preventing premature aging and age-related diseases.¹

Vitamin D and Omega-3 Fatty Acids

Vitamin D and omega-3 fatty acids play an important role in cellular processes and could also protect against aging and age-related chronic diseases. Previous cross-sectional studies have indicated a connection between telomere length and concentrations of both vitamin D and omega-3 fatty acids, as other smaller studies have shown benefits on telomere length or telomerase activity. However, the study authors noted that a recent review determined that the results were inconsistent and larger clinical trials are needed.¹

VITAL Trial Results

The researchers used data from the VITAL trial, which was a large, randomized, double-blind, placebo-controlled, 2x2 factorial study that investigated whether taking daily dietary supplements of vitamin D3 (2000 IU) or omega-3 fatty acids reduces the risk of developing cancer, heart disease, and stroke. The study includes around 26,000 women aged 55 years and older and men aged 50 years and older residing in the US with no prior history of these illnesses.^1,3

Data from VITAL Telomere (NCT04386577), a sub-study of the VITAL trial, was also included, involving 1054 individuals from the VITAL study. The researchers analyzed over 2500 samples from the individuals, examining LTL measured at baseline, year 2, and year 4 using the Absolute Human Telomere Length Quantification Quantitative Polymerase Chain Reaction (PCR) method. The primary outcome focused on changes in LTL between these time points, analyzed using mixed-effects linear regression models to determine the intervention’s effect.¹

The results demonstrated that 2000 IU a day of vitamin D3 supplementation could significantly reduce LTL attrition by 0.14 kilobase pairs (kb) over 4 years compared to placebo. Further results indicated that the vitamin D3 group maintained LTLs approximately 0.035 kb higher per year of follow-up. In contrast, marine n-3 fatty acid supplementation did not significantly impact LTL at either the 2- or 4-year mark. The study authors noted that the findings suggest that consuming 4 years of daily vitamin D3 supplementation could counteract telomere erosion and cellular senescence, slowing aging by 3 years.¹

REFERENCES

1. Zhu H., Manson J., Cook Nancy., Bayu B., Chen L., Kane K., Huang Y., Christen W., Lee I., Dong Y., May 21, 2025. Accessed June 5, 2025. The American Journal of Clinical Nutrition. Vitamin D₃ and marine ω-3 fatty acids supplementation and leukocyte telomere length: 4-year findings from the VITamin D and OmegA-3 TriaL (VITAL) randomized controlled trial. https://doi.org/10.1016/j.ajcnut.2025.05.003

2. Telomere. National Human Genome Research Institute. Updated June 4, 2025. Accessed June 5, 2025. https://www.genome.gov/genetics-glossary/Telomere#:~:text=A%20telomere%20is%20a%20region,the%20telomeres%20become%20slightly%20shorter.

3. Brigham and Women's Hospital. (n.d.). The VITamin D and OmegA-3 TriaL (VITAL). Retrieved June 5, 2025, from https://www.vitalstudy.org/