What are telomeres and can I keep them longer?
Telomeres protect your genetic material, and they shorten over the years, largely determined by your genes. Whether you can keep them longer through lifestyle has not yet been demonstrated in healthy people, and simply pursuing more telomerase activity is not without risk.
Telomeres are protective structures at the ends of your chromosomes, the carriers of your genetic material in every cell. You can think of them as the plastic caps on shoelaces: they prevent chromosomes from fraying or sticking together. With each cell division, telomeres become a little shorter. When they become too short, the cell can no longer divide properly. This contributes to ageing and increases the risk of conditions such as neurodegenerative diseases and cancer.
Your telomere length in adulthood depends to a large extent on your genes, and that is not something you can change. People with inherited conditions in which telomeres shorten abnormally quickly, such as certain forms of bone marrow failure or scarring in the lungs, show most clearly how damaging short telomeres can be. In healthy people, an association between shorter telomeres and earlier death or more disease has been found, but whether one causes the other has not yet been fully proven.
Whether you can keep your telomeres longer through lifestyle choices is the key question. The only direct evidence in humans comes from a small study of 24 men with prostate cancer. Three months of intensive healthy living, including healthy eating, exercise, stress management and social support, increased the activity of telomerase. Telomerase is the enzyme that can replenish telomeres. The researchers themselves stressed that this was an initial, small observation, without a comparison group, in a specific patient population. You cannot conclude from this that healthy people lengthen their telomeres by living better.
There is also an important caveat: the relationship between telomerase and cancer runs in both directions. Cancer cells use telomerase precisely to become immortal. More telomerase is therefore not simply better; depending on the type of cancer it can either increase or decrease risk. This makes raising telomerase activity through supplements or other means a risky goal to pursue without further evidence.
What is now reasonably certain: your genes largely determine your telomere length. Lifestyle plays a role, but evidence that you, as a healthy person, can lengthen your telomeres by living differently or taking supplements is still lacking. The message that the studies together convey is simple: severely and rapidly shortened telomeres are harmful, but actively lengthening telomeres as a personal health goal is a hypothesis, not a proven strategy.
This answer draws on several review articles on the biology and consequences of telomere shortening, one small clinical study in 24 men with prostate cancer, and a case report of one individual that carries no evidential weight. The clinical study had no control group and focused on a specific patient population. No large randomised studies in healthy people are available that demonstrate that lifestyle measurably increases telomere length. The evidence for the basic biology is solid; the evidence for whether you can do anything about it yourself is thin.
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.
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.
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.
How does ageing work and how can you slow it down?
Ageing is well described biologically, but there are no proven means of genuinely slowing it in humans yet. For now, focus on what works: sufficient exercise, a protein-rich diet and avoiding overeating.
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.
Can you lengthen or restore your telomeres?
Healthy adult body cells cannot lengthen their own telomeres, and no proven safe way to do so from the outside yet exists. Be sceptical of supplements or therapies that promise otherwise.