Can you lengthen your telomeres through lifestyle?
Lifestyle can probably slow telomere shortening, but the starting length of your telomeres is largely genetically determined and by far the strongest predictor of how quickly they shorten. Not smoking, exercising regularly and following a Mediterranean diet are the most well-supported steps you can take.
Telomeres are the protective caps at the ends of your chromosomes. They shorten slightly with every cell division, and faster shortening is associated with accelerated biological ageing. Whether you can actively make them longer through lifestyle is a nuanced question: the focus is mainly on slowing the loss, not on turning back the clock.
Quitting smoking is the most robust step you can take. Smoking is strongly associated with noticeably shorter telomeres, even after correcting for weight, blood sugar and alcohol use. Moderate to vigorous physical exercise goes in the opposite direction: it is linked to longer telomeres, presumably because it reduces oxidative stress and low-grade inflammation. Diet matters too: a Mediterranean diet and nutrients such as antioxidants, fibre and omega-3 fatty acids are associated with longer telomeres across multiple studies, while sugary drinks and processed meat are associated with shorter ones. However, those nutrition studies are largely cross-sectional snapshots and cannot establish cause and effect.
The picture for supplements is more mixed. Vitamin D3 (2000 IU per day, for four years) significantly slowed telomere shortening in a large randomised trial: over four years, participants lost an average of 0.14 kilobase pairs less than the placebo group. In the same trial, omega-3 supplementation had no measurable effect on telomere length, which contradicts earlier, smaller positive studies. There is also a small study (40 participants) with an astragalus supplement that found measurable lengthening via increased telomerase activity, but the study is too small to draw firm conclusions. Dietary selenium was associated with longer telomeres in a large population study, but only in women without obesity, and that study cannot establish causality.
Sleep also plays a role, though not necessarily in the way you might expect. Insomnia is associated with shorter telomeres. Notably, excessively long sleep duration was linked in another study to greater telomere shortening over six years, which complicates the relationship.
An important nuance is that the starting length of your telomeres determines more than half of how quickly they shorten. All lifestyle factors combined explain only a modest share of the variation. Lifestyle therefore always operates on top of a baseline that is largely determined by genetics.
This answer draws on multiple large population studies involving thousands of participants, research in which genetic predisposition was used as a natural experiment (making cause and effect more plausible than ordinary observations), and one large randomised trial on vitamin D3 and omega-3. The findings on diet and selenium come from studies that provide only a cross-sectional snapshot, without the ability to distinguish cause from effect. For astragalus, the only available study is too small to support reliable conclusions.
What are telomeres and can I keep them longer?
Keeping telomeres longer sounds appealing, but more telomerase or longer telomeres also carry risks, because cancer cells use the same mechanism. Specific lifestyle interventions have not yet been convincingly proven, so be critical of supplements or tests that claim otherwise.
Does your telomere length tell you anything useful about your health?
Telomere length is a relevant biological measure, but does not give a clear-cut signal: shorter telomeres increase the risk of heart disease and fibrosis, while longer telomeres increase the risk of certain cancers. A commercial telomere test in blood is therefore difficult to translate into concrete health advice.
Can you have your telomeres measured, and is there any value in doing so?
A telomere test is technically possible but currently provides little actionable information for you as an individual, because measurement methods differ considerably from one another and a single average number misses much relevant variation. Only get tested if your doctor has a concrete medical reason to do so.
Which lifestyle factors influence your biological age the most?
Sitting for prolonged periods, a disrupted circadian rhythm and muscle loss are the best-supported negative factors for your biological age; exercising regularly and maintaining a consistent sleep-wake rhythm are the most concrete steps you can take right now.
Can you lengthen or restore your telomeres?
Genuinely lengthening telomeres in humans has not yet been convincingly proven; addressing inflammation, stress and unhealthy lifestyle habits currently has the strongest support if you want to protect your telomeres.
What does telomerase do to the length of your telomeres?
Telomerase keeps telomeres intact for longer by compensating for shortening during cell division, but in most body cells the enzyme is barely active, causing telomeres to shrink over time.