Glossary · Biology
Autophagy
In short
Autophagy is the cell’s recycling programme: it packages damaged or surplus components and breaks them down into their building blocks. When mitochondria are specifically broken down, this is called mitophagy.
Autophagy is driven above all by nutrient shortage. A central switch is mTOR: when it is active, the cell grows; when it is inhibited, for example during fasting or by rapamycin, the cell tidies up. The Nobel Prize in Medicine 2016 was awarded for deciphering the mechanisms.
The gap lies in measurement: autophagy cannot simply be determined in human blood. Many claims, such as after how many hours of fasting it “kicks in”, come from cell culture and animal studies. In humans there are mostly only indirect markers.
Well understood in the cell, hard to measure in humans.
Where this comes up in the fact checks
- Fasting & autophagy – Autophagy is considered the most important promise of intermittent fasting.
- Spermidine – In yeast, flies and mice it stimulates cellular clean-up; in humans the chain of evidence is thinner, but not empty.
- Rapamycin – Inhibits mTORC1 and thus activates autophagy; outcome data on ageing in humans are lacking.
- Urolithin A – Stimulates mitophagy, the recycling of worn-out mitochondria.
Sources
Related terms: Mitochondria · Hormesis · Surrogate marker
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