Vitamin D and the Longevity Headline
None of the four studies the article cites shows that vitamin D supplementation extends life.
Dr. Volker Spitzer · 18 October 2026
The claim
The Hamburger Abendblatt ran a piece on 17 October 2026 under the headline 'Vitamin D und Langlebigkeit: Studien deuten auf überraschende Wirkung' [1] (translated to English: Vitamin D and longevity: Studies suggest a surprising effect). Its teaser casts vitamin D status as something that may shape mortality risk and life expectancy.
Read past the headline and the article turns more cautious. It draws on four studies and quotes Sebastian Grönke, of the Max Planck Institute for Biology of Ageing, who dismisses the idea that vitamin D slows ageing or extends life [1]. That gap between what the headline says and what the evidence shows is the translation problem in miniature.
Articles like this one, and the loose handling of evidence behind them, are the reason I wrote From Evidence to Consumers. The book explains which study designs can support which claims, and where the step from a trial result to consumer advice tends to break down. So let's turn to the newspaper article itself.
Four studies, four levels of evidence
Just one of the four studies looked at a hard outcome in randomised trials, and its main analysis showed no significant effect.
| Study | Design | What the article reports | What the evidence supports |
|---|---|---|---|
| Sutherland 2022 [2] | Non-linear Mendelian randomisation; UK Biobank, 307,601 adults | Low vitamin D status raises premature death; risk 25% higher below 25 nmol/L, sixfold below 10 nmol/L | Not confirmed: the authors' 2024 reanalysis found no association with all-cause, cancer or cardiovascular mortality [3] |
| Kuznia 2023 [4] | Systematic review and individual patient data meta-analysis; 14 RCTs, 104,727 participants | Daily vitamin D lowers cancer mortality by 12% | Primary analysis across all 14 trials not significant (RR 0.94; 95% CI 0.86 to 1.02). The 12% comes from a subgroup of 10 daily-dosing trials (RR 0.88; 0.78 to 0.98), a comparison between trials rather than a randomised one; two co-authors dissociated themselves from this interpretation [4] |
| Zhu 2025 [5] | Ancillary analysis of a randomised trial; 1,031 analysed | Telomeres shortened more slowly, worth almost three years of ageing | Low certainty for a biomarker; no clinical outcome measured |
| Gwenzi 2023 [6] | Meta-analysis of 8 RCTs; 592 patients with cancer or precancerous lesions | Lower IL-6 and CRP, without a clear association | IL-6 and CRP reductions not significant; only TNF-α fell significantly; studied in people with cancer or precancerous lesions, not in healthy older adults |
The first study supplies the article's most striking numbers [2], and these very figures have since been called into question. Its original analysis relied on the residual method, which assumes that genetic effects on vitamin D are the same across the whole population. When the data were reanalysed with the doubly-ranked method, the link with mortality vanished; the authors say only that they cannot exclude an effect limited to severe deficiency [3].
In February 2025 the European Heart Journal retracted the same group's companion paper on cardiovascular risk, after a reanalysis did not support it [7]. Neither development appears in the Abendblatt article.
The cancer mortality result is the best evidence the article offers, and it is still modest. The 12% reduction comes from comparing trials that dosed daily with trials that gave boluses (p for interaction = 0.042); nobody was randomised to one regimen or the other [4]. With a pooled cancer death rate of about 1.9%, that works out, by approximate calculation, to roughly two fewer deaths per 1,000 people across the trial periods.
The telomere trial in detail
Participants who took 2,000 IU of vitamin D3 a day lost about 140 base pairs less leukocyte telomere length over four years than those given placebo [5].
| Feature | VITAL Telomere sub-study [5] |
|---|---|
| Parent trial | VITAL: randomised, double-blind, placebo-controlled, 2 × 2 factorial; 25,871 US women aged 55+ and men aged 50+ |
| Telomere cohort | 1,054 participants seen in person at one Boston centre; 2,571 samples from 1,031 participants analysed |
| Intervention | Vitamin D3 2,000 IU (50 µg) and/or marine omega-3 fatty acids 1 g daily |
| Measurement | Leukocyte telomere length by quantitative PCR at baseline, year 2 and year 4 |
| Vitamin D3 effect | 0.14 kb less attrition over four years (95% CI 0.01 to 0.27; p = 0.039) |
| Omega-3 effect | No significant effect |
| Baseline status | Adequate on average: mean 25(OH)D in VITAL was 30.8 ng/mL [8] |
For nutrition research, this is a strong design. What remains open is how much weight its endpoint can bear.
Why the telomere result cannot carry the headline
Applying GRADE, certainty that vitamin D3 slows leukocyte telomere attrition begins high and drops to low after two downgrades.
| Domain | Assessment | Effect on certainty |
|---|---|---|
| Risk of bias | Randomised and double-blind; telomere data come from a single-centre sub-cohort of about 4% of VITAL | Not downgraded |
| Indirectness | Telomere length in white blood cells is a marker, not a health outcome; genetically longer telomeres raise the risk of several cancers while lowering coronary risk [9] | Downgraded one level |
| Imprecision | Lower confidence limit of 0.01 kb, close to no effect; a single result at p = 0.039 | Downgraded one level |
| Consistency | One trial, not replicated; in DO-HEALTH (post hoc, 777 adults aged 70+), epigenetic clocks responded to omega-3, not to vitamin D alone [10] | Not assessable; adds doubt |
| Clinical outcomes | Vitamin D did not change all-cause mortality in VITAL (HR 0.99; 95% CI 0.87 to 1.12) [8] | No support for a longevity claim |
The 'three years of ageing avoided' figure needs a warning of its own: nobody observed it. The authors arrived at it by setting 140 base pairs against the attrition rate seen in a different cohort, about 460 base pairs over ten years [5].
Here, indirectness counts for more than it usually does. A surrogate is only useful when shifting it dependably shifts the outcome, and with telomeres not even the direction of benefit is settled. In Mendelian randomisation, genetically longer telomeres are associated with higher odds of glioma and lung adenocarcinoma, along with other cancers [9].
Where the article holds up, and where it slips
The expert commentary stands up; the framing and the first piece of evidence do not.
What holds up
- Dr. Grönke (the expert which has been interviewed for the article) draws a line between correcting a deficiency and slowing ageing, something supplement coverage often fails to do [1].
- His scepticism about telomeres as a marker of ageing fits the indirectness problem described above, though the inflammatory markers he favours have not been validated as surrogates of ageing either.
- The article cautions against overdosing and names its sources.
Where it slips
- The headline and teaser hold out an effect on longevity that the article's own expert dismisses.
- The mortality figures depend on an analysis that the authors' own reanalysis failed to confirm [3].
- The 12% subgroup result is reported; the non-significant primary analysis is not [4].
- Every effect is expressed as a relative risk, which makes it appear larger than it is.
- The article connects telomere shortening with cancer, yet genetic evidence associates longer telomeres with a higher risk of several cancers [9].
- It recommends covering nutrient needs mainly through diet. With vitamin D, though, food provides only 10 to 20% of the body's supply under typical conditions, and synthesis in the skin makes up the rest [11].
- Dr. Grönke's view that macronutrients matter more than micronutrients for ageing appears as expert opinion, with no evidence offered in support.
From trial to shelf
At 50 µg, the trial dose is two and a half times the 20 µg per daily dose that Germany's Federal Institute for Risk Assessment (BfR) proposes as the ceiling for food supplements [11]. That proposal carries no legal force, but it is the national reference point.
Safety is not really the issue. In 2023 EFSA kept a tolerable upper intake level of 100 µg per day for adults [12], comfortably above 50 µg. The issue is that a reader who copied the trial would exceed the national recommendation on the strength of a biomarker.
There is a second gap that is easy to overlook. At baseline the participants were adequately supplied, so the result tells us nothing about correcting deficiency, which is where the argument for supplementation is strongest.
Bottom line
None of the four studies the article cites shows that vitamin D supplementation extends life. The mortality analysis fell apart on reanalysis, the cancer mortality benefit depends on a subgroup comparison, and the telomere and inflammation findings are low-certainty biomarker results.
A fair sentence for consumers might run: It is worth correcting a genuine vitamin D deficiency, and taking vitamin D daily may lower cancer mortality slightly. Nothing shows that supplements slow ageing or extend life in people whose supply is already adequate.
The verdict would change with an adequately powered trial that takes mortality as its primary outcome in people with low vitamin D status, since that is the group in which a benefit is most plausible. Until such a trial exists, the headline promises more than the data can deliver.
References
- Sekertzi D. Vitamin D und Langlebigkeit: Studien deuten auf überraschende Wirkung. Hamburger Abendblatt [Internet]. 2026 Oct 17 [cited 2026 Oct 18]. Available from: abendblatt.de
- Sutherland JP, Zhou A, Hyppönen E. Vitamin D deficiency increases mortality risk in the UK Biobank: a nonlinear Mendelian randomization study. Ann Intern Med. 2022;175(11):1552-9. doi:10.7326/M21-3324
- Hyppönen E, Sutherland JP, Zhou A. Vitamin D deficiency and mortality: a reanalysis of a prior Mendelian randomization study [letter]. Ann Intern Med. 2024;177(12):1743-6. doi:10.7326/ANNALS-24-02796
- Kuznia S, Zhu A, Akutsu T, Buring JE, Camargo CA Jr, Cook NR, et al. Efficacy of vitamin D3 supplementation on cancer mortality: systematic review and individual patient data meta-analysis of randomised controlled trials. Ageing Res Rev. 2023;87:101923. doi:10.1016/j.arr.2023.101923
- Zhu H, Manson JE, Cook NR, Bekele BB, Chen L, Kane KJ, et al. 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. Am J Clin Nutr. 2025;122(1):39-47. doi:10.1016/j.ajcnut.2025.05.003
- Gwenzi T, Zhu A, Schrotz-King P, Schöttker B, Hoffmeister M, Brenner H. Effects of vitamin D supplementation on inflammatory response in patients with cancer and precancerous lesions: systematic review and meta-analysis of randomized trials. Clin Nutr. 2023;42(7):1142-50. doi:10.1016/j.clnu.2023.05.009
- Retraction of: Non-linear Mendelian randomization analyses support a role for vitamin D deficiency in cardiovascular disease risk. Eur Heart J. 2025;46(15):1456. doi:10.1093/eurheartj/ehaf081
- Manson JE, Cook NR, Lee IM, Christen W, Bassuk SS, Mora S, et al. Vitamin D supplements and prevention of cancer and cardiovascular disease. N Engl J Med. 2019;380(1):33-44. Summary of principal results
- Telomeres Mendelian Randomization Collaboration; Haycock PC, Burgess S, Nounu A, Zheng J, Okoli GN, et al. Association between telomere length and risk of cancer and non-neoplastic diseases: a Mendelian randomization study. JAMA Oncol. 2017;3(5):636-51. Record
- Bischoff-Ferrari HA, Gängler S, Wieczorek M, Belsky DW, Ryan J, Kressig RW, et al. Individual and additive effects of vitamin D, omega-3 and exercise on DNA methylation clocks of biological aging in older adults from the DO-HEALTH trial. Nat Aging. 2025;5(3):376-85. doi:10.1038/s43587-024-00793-y
- Bundesinstitut für Risikobewertung. Aktualisierung (2023): Höchstmengenvorschläge für Vitamin D in Lebensmitteln inklusive Nahrungsergänzungsmitteln. Berlin: BfR; 2023. PDF
- EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA); Turck D, Bohn T, Castenmiller J, de Henauw S, Hirsch-Ernst KI, et al. Scientific opinion on the tolerable upper intake level for vitamin D, including the derivation of a conversion factor for calcidiol monohydrate. EFSA J. 2023;21(8):e08145. doi:10.2903/j.efsa.2023.8145