What does autophagy do against ageing and disease?
Autophagy plays a central role in keeping cells healthy and is linked to protection against Alzheimer's, Parkinson's and early-stage cancer, but the system cuts both ways: too little and too much can both be harmful, depending on the context. What you can do now: periodic fasting is being studied as a way to stimulate autophagy, but larger independent studies are needed.
Autophagy is the self-cleaning system of cells. It breaks down damaged protein clumps, worn-out cell components and invading pathogens, and recycles the building blocks. Without that clean-up function, cells cannot work properly, and disruptions to it are linked to a range of serious diseases.
In brain cells, this system is especially important. Brain and nerve cells barely renew themselves, so they depend entirely on autophagy to keep themselves clean. When that goes wrong, toxic protein clumps and damaged energy-producing structures build up. This process has been linked to the development of Alzheimer's, Parkinson's and Huntington's disease. Certain inherited variants are seen as a clear risk factor.
In cancer, the picture is two-sided. At an early stage, autophagy acts as a brake on harmful growth: it clears away damaged cell components that could otherwise trigger a cell to go rogue. But once a tumour has already formed and comes under stress, such as a shortage of oxygen or nutrients, that same autophagy can actually help tumour cells survive. Whether you want to activate or suppress autophagy as a therapy therefore depends entirely on the stage of the disease.
A specific form of autophagy appears to be able to slow down cell ageing. This is a recent finding and more evidence is needed. Animal studies also show a downside: too much autophagy sustained for too long can be harmful. In kidneys, persistent overactivation contributed to scarring and chronic kidney disease. This was confirmed in kidney tissue from people with chronic kidney disease.
In experiments with cells and animals, around 80 plant-based substances have already been studied that can switch autophagy on or off, including curcumin, the active compound in turmeric. The results are mixed, and this has barely been tested in people. A small study of 30 participants showed that a fasting-mimicking diet lasting several days measurably increased autophagy in blood cells, with favourable effects on blood sugar and insulin sensitivity, meaning how well the body responds to insulin. That study was funded by the company selling the diet, however, which makes the results less independent.
This answer is based on laboratory research, cell and model studies in animals, and a limited number of studies in people, including a small pilot with 30 participants and analyses of kidney tissue from people with chronic kidney disease. For the link with brain diseases and cancer, the evidence comes largely from laboratory and animal work; large studies in people are mostly lacking. The researchers themselves describe it as a promising but early-stage field. The pilot on the fasting diet was funded by a commercial party, which limits its independence.
What is autophagy and can I switch it on myself?
Autophagy is your cells' clean-up system, and research shows you can measurably switch it on at a molecular level by eating substantially less for several days, around 850 calories a day.
Can you measure autophagy in your body?
Autophagy can be measured, but only in a laboratory using cells or tissue material. No reliable test is available for use at home or at a general practitioner's surgery.
Can meditation do anything about ageing at the cellular level?
Meditation appears to activate an enzyme that protects chromosome caps from ageing, although the studies are still too small to draw firm conclusions. Meditation is in any case safe and has positive effects beyond cell biology, so the barrier to trying it is low.
What exactly does senescence do to your cells as you age?
Senescent cells stop dividing and secrete inflammatory substances that damage tissues over time. They are necessary in youth, but when they accumulate they accelerate ageing and disease.
Does exercise activate autophagy?
Exercise activates autophagy in muscle cells through well-described mechanisms, but most of the evidence comes from animal and laboratory research. In practice: regular, moderate movement appears most beneficial; extremely excessive strain could actually disrupt the system.
How many hours of fasting are needed to activate autophagy?
There is no proven hourly threshold for activating autophagy in humans. If you use this as a reason for a fasting pattern, be aware that the mechanistic idea is plausible, but the practical threshold in humans has not yet been established.