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.
Telomerase is an enzyme that replenishes the ends of chromosomes, the telomeres, with each cell division. It continuously attaches new pieces of DNA (the sequence TTAGGG) to those ends. Without this enzyme, telomeres become slightly shorter with every cell division, until the cell stops dividing. That process is regarded as a biological ageing clock.
In most ordinary body cells, telomerase is barely active after the early embryonic phase. As a result, those cells become exhausted with repeated division: the telomeres grow too short, the cell enters a kind of dormant state (senescence) and no longer divides. Stem cells and germ cells are an exception; these keep telomerase active for longer.
Telomerase does not operate without regulation either. Specific proteins on the telomeres determine when the enzyme gains access. The shortest telomeres take priority: they are replenished first. In this way the system maintains a balance and the telomere does not grow indefinitely.
There is an important downside. In most cancer cells, telomerase becomes active again, allowing those cells to keep dividing without limit. Telomere shortening in healthy cells acts precisely as a brake: a cell that has divided too many times simply stops. That brake also restrains tumour formation.
When telomerase does not function properly due to an inherited mutation, so-called telomeropathies arise. These are conditions in which telomeres wear down structurally too quickly, with serious consequences for tissues that require a great deal of cell division, such as bone marrow and lungs. This shows how essential a properly functioning telomerase system is.
All claims are based on multiple studies (PMIDs 24993696, 18432920, 16741708, 21429730, 29415479, 9524748, 40609992). The mechanistic and cellular findings are robust; the role in male fertility is insufficiently supported and has not been included as a conclusion.
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.
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.
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.
What exactly does senescence do to your cells as you age?
Senescent cells stop dividing, accumulate with age and cause damage throughout the body through a constant stream of inflammatory substances. They are both a protector (a brake on cancer) and a cause of damage, and that makes targeted intervention more complex than it appears.
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.