Telomerase

Telomerase is an enzyme that extends telomeres — the protective caps at the ends of chromosomes. In most adult cells, telomerase activity is low or absent. As cells divide, telomeres shorten. When they get short enough, the cell stops dividing (senescence) or dies (apoptosis). Shorter telomeres are associated with older biological age. The longevity interest in telomerase is straightforward: if you could activate it, you might slow or reverse cellular aging. The biology is real. The translation to supplementable peptides is where the evidence gets thin. Epithalon (Ala-Glu-Asp-Gly) is the primary compound in this space — it was shown to activate telomerase in cell culture by Khavinson et al. (2003). The research comes predominantly from one Russian group, using in vitro and rodent models. Human trial data is absent. A complication: telomerase activation is also how some cancer cells become immortal. The same enzyme that extends telomeres in normal cells is overactivated in tumours. This doesn't make epithalon a cancer risk — the evidence doesn't support that claim — but it means the "activate telomerase to live longer" narrative requires more caution than the longevity community typically applies to it.