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07. Telomeres and Telomerase: What They Tell Us About Ageing and Longevity
Telomeres and telomerase: what they tell us about ageing and longevity
Telomeres form protective ends on chromosomes, which carry our genetic information. They help prevent damage and unwanted joining of chromosome ends. In many cells, they shorten with repeated division, and critically short telomeres can lead to a halt in division — cellular senescence. Telomerase is an enzyme complex that can replenish telomeric DNA. The proper functioning of these mechanisms matters for tissue renewal, which is why they are also studied in relation to healthy ageing and longevity. This article explains what genetic studies, exercise research and clinical measurements tell us about telomeres.
Sources for the introduction: [1] [2] [3] [4] [5] [6] [7]
What are telomeres?
Telomeres are structures at the ends of chromosomes made up of repeated DNA sequences and associated proteins. They help protect chromosome ends from damage and unwanted joining. They can shorten as many types of cells divide repeatedly. [1] [2]
What role does telomerase play?
Telomerase is an enzyme complex that can add telomeric DNA. Its activity is regulated and varies between cells. Telomere maintenance is important for tissue renewal, but cancer cells can also exploit the ability to keep dividing over time. [2]
| Term | What it describes |
|---|---|
| Telomeres | Protective structures at the ends of chromosomes. |
| Telomerase | An enzyme complex involved in adding telomeric DNA. |
| Telomere length | A measured characteristic of a particular sample that needs to be interpreted in context. |
Elizabeth Blackburn, Carol Greider and Jack Szostak received the 2009 Nobel Prize for their discoveries concerning chromosome protection by telomeres and telomerase. Recognition of a fundamental mechanism does not confirm the effectiveness of a “rejuvenating” product. [1]
How are telomeres linked to senescence?
Critically short or disrupted telomeres can trigger a DNA damage response and halt cell division. This mechanism is associated with replicative senescence. However, findings in cell culture cannot be directly translated into years of human life. [2]
Replicative senescence means a halt to division after repeated rounds of cell division.
When reading research, it is helpful to distinguish three levels: what happens in a cell, what the outcome is for a tissue, and what it means for human health. Extending a cell’s ability to divide does not, by itself, demonstrate a beneficial extension of an organism’s life.
Why is “the longer the telomeres, the better” not a valid rule?
Genetic analysis of disease risks
A Mendelian randomisation study published in 2017 examined genetic variants associated with telomere length and data on 35 cancers and 48 non-neoplastic diseases. Genetically determined longer telomeres were associated with a higher risk of several cancers but a lower risk of some non-neoplastic diseases. [3]
This method uses genetic differences to investigate possible causal relationships. It is not a supplement experiment or a direct prediction of an individual’s risk. However, it illustrates why no single length can be described as universally advantageous.
A rare inherited model of long telomeres
A 2023 study examined families with variants of the POT1 gene associated with long telomeres. The authors described a predisposition to clonal haematopoiesis and various benign and malignant tumours. [4]
Clonal haematopoiesis means that a larger proportion of blood cells originates from a single cell lineage. Findings from a rare genetic syndrome cannot be applied to everyone with above-average telomere length. Nevertheless, they provide another reason why research must also address the safety of telomere maintenance.
Exercise and telomeres: what did a randomised study find?
A six-month study published online in 2018 was completed by 124 previously inactive healthy people. It compared endurance, interval and resistance training with a control group. All three training programmes increased maximal oxygen uptake. Endurance and interval training also increased telomerase activity and telomere length in the blood cells examined; the same result was not observed with resistance training. [5]
Maximal oxygen uptake indicates how much oxygen the body can use during intense exertion.
This does not mean resistance training had no benefit. The study itself recorded improved fitness in this group too. A difference in one cellular marker is not an overall assessment of a training programme.
Furthermore, the research did not demonstrate longer life or a reduction in biological age by a specific number of years. It measured selected blood markers over a limited period.
What can a telomere length test tell us?
The method and laboratory affect interpretation
An international comparison of ten laboratories, published online in 2014 and in the journal in 2015, found differences between absolute measurement results. The ranking of samples by relative length was more consistent than the numerical values themselves. [6]
This is a historical methodological study, not an assessment of every test available today. Its practical question remains important: when comparing two results, do they use comparable methods, sample processing and reference populations?
Targeted clinical diagnosis has a different purpose
A 2018 study demonstrated the usefulness of flowFISH measurement for selected clinical indications. Among 38 patients with unexplained bone marrow failure, the result influenced treatment or blood-forming cell donor decisions in 9 cases. [7]
The flowFISH method uses fluorescent labelling of telomeric DNA and measurements in individual cells.
That is a specific medical purpose. It does not prove that a commercial telomere test can reliably calculate the age of the whole body or remaining life expectancy.
| Question | Why it matters |
|---|---|
| Which sample and method were used? | The result relates to a specific measurement. |
| What is the value compared with? | We need to know the reference population. |
| What is the measurement uncertainty? | A small difference does not necessarily indicate a biological change. |
| Which decision is the test intended to support? | A laboratory result should have a clear purpose. |
Conclusion: telomere length is not the whole story of ageing
Telomeres and telomerase help explain cell division and tissue renewal. However, interpreting results requires attention to the cell type, measurement method and health context. Longer telomeres or higher telomerase activity alone do not prove rejuvenation or an extension of human life.
When reading further research, we should therefore distinguish a change in a laboratory marker from a demonstrated health benefit and also consider the safety of the interventions studied.
Frequently asked questions
Are telomeres precise biological clocks?
Their length is one biological characteristic. The number alone cannot be treated as the precise age of all organs or as a countdown of the years remaining.
Do longer telomeres automatically mean a healthier body?
No. Genetic research shows different associations depending on the disease. Context matters, rather than maximising a single marker.
Is increased telomerase activity proof of rejuvenation?
No. Enzyme activity, telomere length, health outcomes and lifespan are different parameters being studied.
Does the exercise study prove that resistance training does not work?
No. In the cited study, fitness also improved with resistance training. The absence of a change in a telomere marker does not mean the absence of all benefits.
Does this article recommend supplements to lengthen telomeres?
No. It explains research and does not recommend products or interventions affecting telomerase activity. The cited papers do not confirm that such a supplement extends human life.
Sources and further reading · 7 sources
- Nobel Assembly at Karolinska Institutet (2009): The Nobel Prize in Physiology or Medicine 2009 – Press release.
- Nobel Committee for Physiology or Medicine (2009): Maintenance of chromosomes by telomeres and the enzyme telomerase. Scientific background from the Nobel Committee.
- Telomeres Mendelian Randomization Collaboration (2017): Association Between Telomere Length and Risk of Cancer and Non-Neoplastic Diseases: A Mendelian Randomization Study. JAMA Oncology. Genetic analysis. DOI: 10.1001/jamaoncol.2016.5945.
- DeBoy E. A. et al. (2023): Familial Clonal Hematopoiesis in a Long Telomere Syndrome. New England Journal of Medicine. Family genetic study. DOI: 10.1056/NEJMoa2300503.
- Werner C. M. et al. (2019; online 2018): Differential effects of endurance, interval, and resistance training on telomerase activity and telomere length in a randomized, controlled study. European Heart Journal. Randomised study. DOI: 10.1093/eurheartj/ehy585.
- Martin-Ruiz C. M. et al. (2015; online 2014): Reproducibility of telomere length assessment: an international collaborative study. International Journal of Epidemiology. Methodological study; published correction. DOI: 10.1093/ije/dyu191. Correction: DOI: 10.1093/ije/dyv171.
- Alder J. K. et al. (2018): Diagnostic utility of telomere length testing in a hospital-based setting. PNAS. Clinical use of testing. DOI: 10.1073/pnas.1720427115.
Sources selected by the author, not a systematic review of all publications. This article is educational and does not replace diagnosis or individual medical advice.
