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.
Telomeres are the protective caps at the ends of your chromosomes. With each cell division they become a little shorter, because the enzyme that copies DNA cannot replicate the very last segments. In most cells of the body, the enzyme capable of replenishing telomeres (telomerase) is switched off, making this shortening unavoidable. When telomeres reach a critical minimum length, the cell permanently stops dividing. The accumulation of such 'aged' cells in tissues contributes to the ageing process.
Genuinely lengthening telomeres in humans has not been convincingly demonstrated so far. In animal research and cell studies, increasing telomerase activity can actually lengthen telomeres and slow cellular ageing, through gene therapy or small molecules. But clinical evidence in humans is still limited. There is one small study (40 participants) that provides indications that an Astragalus-based supplement significantly increased telomere length after six months, with fewer short telomeres in the group that received the supplement compared with placebo. No side effects were reported. This is an interesting finding, but with such a small group no firm conclusions can yet be drawn.
Lifestyle also plays a role, although the evidence is diffuse. Stress reduction and healthier lifestyle habits have been linked to slightly longer telomeres in small studies. But part of this effect may be an artefact: when your lifestyle improves, the composition of your blood changes, so that cells with naturally longer telomeres are counted relatively more often. In the measurement this looks like 'lengthening', while no actual growth is taking place.
The greatest risk of stimulating telomerase is cancer. In 85 to 90 percent of all tumour cells, telomerase is actually overactive, allowing cancer cells to keep dividing without limit. Any approach that raises telomerase throughout the entire body therefore carries a theoretical risk of promoting cancer growth. This makes it one of the most difficult tensions in this field of research: precisely what allows cells to live longer can also feed tumour cells. Inflammation and oxidative stress accelerate telomere shortening and are linked to a higher risk of cardiovascular disease; addressing those factors therefore has considerably more evidence behind it than direct telomere supplements.
This answer draws on multiple expert review studies and one small randomised study with 40 participants (Astragalus supplement). The basic biology of telomere shortening and senescence is robustly supported. The evidence for telomere lengthening in humans is thin: the mechanistic evidence comes largely from cell and animal research, and the only randomised study in humans is too small for firm conclusions. The researchers themselves emphasise that clinical evidence in humans is still limited and that larger studies are needed.
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.
Why do your telomeres get shorter as you age?
Telomeres shorten because the copying process during cell division cannot fully reproduce the ends of chromosomes, and the repair enzyme telomerase is switched off in adult body cells. Stress and oxidative damage can accelerate that process further, but the fundamental mechanism is unavoidable as long as cells divide.
How do telomeres protect your DNA?
Telomeres protect your chromosome ends through a system of proteins that simultaneously prevents false alarms and harmful fusions. If that system fails due to inherited defects, you can develop serious ageing-related diseases.
Can you repair DNA damage, or can you only prevent it?
Your body actively repairs DNA damage through multiple well-studied mechanisms, but that repair is not always perfect and becomes less effective when the cell is under excessive strain or grows older.
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.
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.