What are telomeres and can we lengthen them?

The answer

Telomeres are repetitive DNA sequences (TTAGGG in humans, repeated roughly 2,500 times) at chromosome ends that prevent degradation and fusion during cell division. Because DNA polymerase cannot fully replicate chromosome ends (the end-replication problem), telomeres shorten by 50 to 200 base pairs per cell division. When they reach a critical length, the cell enters senescence or apoptosis. The enzyme telomerase can rebuild telomeres and is active in stem cells, immune cells, and, problematically, about 90% of cancers (allowing unlimited proliferation). Elizabeth Blackburn, Carol Greider, and Jack Szostak received the 2009 Nobel Prize for discovering telomerase. Research shows that chronic stress, poor sleep, smoking, and obesity accelerate telomere shortening, while exercise, meditation, and healthy diet are associated with longer telomeres. While artificially activating telomerase in mice extended lifespan, doing so in humans carries a significant cancer risk.