Vitamin D3 Supplementation and Telomere Length
Daily supplementation with vitamin D3 (2,000 IU/day) can reduce telomere attrition by approximately 140 base pairs over 4 years, potentially counteracting cellular aging processes. 1
Evidence on Vitamin D3 and Telomere Length
The relationship between vitamin D3 supplementation and telomere length has been investigated with mixed results:
The most recent high-quality evidence comes from the VITAL randomized controlled trial (2025), which demonstrated that 2,000 IU/day of vitamin D3 supplementation significantly decreased leukocyte telomere length (LTL) attrition by 0.14 kilobase pairs over 4 years compared to placebo (p=0.039) 1
In contrast, the D-Health Trial (2023) found no significant difference in telomere length between vitamin D and placebo groups after 4-5 years of monthly vitamin D supplementation in older adults who were largely vitamin D replete 2
Observational data from the Nurses' Health Study showed that higher plasma 25-hydroxyvitamin D levels were significantly associated with longer telomere length (p for trend = 0.05) 3
However, a cross-sectional study in men found no association between 25(OH)D or 1,25(OH)2D levels and relative leukocyte telomere length 4
Mechanisms of Action
Vitamin D may influence telomere biology through several mechanisms:
- Anti-inflammatory effects that reduce oxidative stress on telomeres 5
- Anti-cell proliferation mechanisms that may slow telomere shortening 3
- Potential influence on telomerase activity, which is crucial for maintaining telomere length 5
Clinical Implications
Telomere shortening has been associated with:
- Increased risk of cardiovascular events 6
- Reduced immune response 6
- Higher mortality 6
- Central obesity 6
- Lifetime accumulation of stress 6
Dosing Recommendations
Based on the most recent and highest quality evidence:
- For telomere maintenance: 2,000 IU/day of vitamin D3 appears effective 1
- For general vitamin D maintenance:
Important Considerations
- Monitoring: Measure serum 25(OH)D levels after 3-6 months of treatment to ensure adequate dosing 7
- Calcium interaction: Total calcium intake may modify the association between vitamin D levels and telomere length 3
- Individual factors: Consider factors that affect vitamin D requirements such as obesity, skin pigmentation, and medication use 7
Potential Pitfalls
- Using single large annual doses is not recommended and may increase risk of adverse effects 7
- Monthly dosing (as used in the D-Health Trial) may not be as effective as daily dosing for telomere maintenance 1, 2
- Failure to account for baseline vitamin D status may affect outcomes, as benefits may be more pronounced in those with deficiency 2
Conclusion
The most recent high-quality evidence supports that daily vitamin D3 supplementation at 2,000 IU/day may help reduce telomere attrition over time 1. This effect appears to be specific to daily dosing rather than monthly supplementation 2. The benefit may be more pronounced in individuals with lower baseline vitamin D levels, though more research is needed to confirm this relationship.