Ageing research has moved from a marginal field to one attracting substantial investment. That has produced genuine science and an industry of products that borrow its credibility.
What is established
That ageing involves identifiable biological processes rather than being simple wear. Cellular senescence, changes to how genes are regulated, accumulated damage to mitochondria, and several others are well characterised.
That interventions in animals can extend healthy lifespan meaningfully. This is reproducible and it is in animals.
That a handful of existing drugs show effects on ageing markers in humans, and are being trialled for that purpose.
What is not
Any intervention shown to extend human lifespan in a controlled trial. None exists. The trials that would establish it take decades by nature.
Any supplement sold for longevity with evidence beyond animal or cell studies. The gap between mouse and human results is where most of the product claims live.
The measurement problem
Biological age clocks – tests claiming to measure how old your body is – correlate with chronological age and with some health outcomes. Whether changing the number changes anything real is unknown, and the tests are sold as though it does.
What actually works
The unglamorous things. Not smoking, regular physical activity, maintaining a healthy weight, sleeping enough, and social connection. Each has decades of evidence and none can be sold in a bottle.
How to read a claim
Ask whether it was tested in humans, over what period, against what comparison, and who paid. Most longevity marketing fails at the first question.