09
Stem cell exhaustion
The repair pool runs low
Every tissue keeps a reserve of unspecialised cells — apprentices, waiting to replace the workers who wear out. The reserve shrinks over the years, and the ones left answer the call more slowly. It is why a cut closes in three days at sixteen and takes a fortnight at sixty.
What you can dosomething you can do
Nothing you can buy, and clinics offering stem cell injections for ageing are selling well ahead of the evidence. What protects the reserve is unglamorous and free: sleep, enough protein, lifting something heavy twice a week, and not smoking.
The science, in one sentence
The reserve of cells that replaces worn-out tissue shrinks and answers more slowly, so healing slows and tissues thin.
In the glossary
Back to all twelve