What does autophagy do for ageing and disease?
Autophagy is a genuine part of the ageing process and plays a role in many age-related diseases, but the translation into proven human interventions has not yet been made. What you can do now: exercising regularly, sleeping enough and fasting occasionally are the best-supported ways to keep this cellular system active.
Autophagy is your cells' waste-management system: damaged proteins and worn-out components are packaged up and broken down via lysosomes (a kind of cellular stomach). As you grow older, this system loses its power. Multiple review studies describe this decline as one of the central drivers of ageing, because the accumulation of cellular damage then accelerates.
Impaired autophagy has been linked to a broad range of age-related diseases: brain diseases such as Alzheimer's and Parkinson's, heart disease, diabetes and joint conditions. The association has been described consistently, but cause and effect are not always clear. In cancer the role is even ambiguous: autophagy can both suppress tumour growth and help cancer cells survive, depending on the stage of the disease. That makes it difficult to use autophagy as a straightforward therapeutic target.
In animal and laboratory research, well-functioning autophagy consistently extends lifespan. Whether that applies directly to humans has not yet been demonstrated, but the associations are comparable across yeast, worms, flies and mice.
The most concrete pointer to a practical handle comes from research into fasting and spermidine. Spermidine is a substance that occurs naturally in wheat germ, soya and cheese. Fasting raises spermidine levels, including in humans. Spermidine then promotes autophagy. In animal models, the protective effect of fasting on the heart and on joint inflammation disappeared as soon as spermidine synthesis was blocked. That points to a clear chain of events, but the translation into concrete health effects in humans has not yet been made.
Exercise, better sleep and lower calorie intake are described in review studies as ways to slow the age-related decline of autophagy. Large randomised trials in humans using hard endpoints are largely absent. Direct drugs that steer autophagy are under active investigation, but their safety and efficacy in humans have not yet been proven. One important note: several authors of these studies have commercial interests in companies developing this type of drug.
Based on multiple review studies and a mechanistic study in model organisms (yeast, worms, flies, mice) with additional small human data for spermidine/fasting. No large RCTs in humans using hard endpoints are available. Potential conflicts of interest have been reported for the pharmacological modulators.
What is autophagy and can I activate it myself?
You can promote autophagy yourself through fasting or temporarily eating significantly less, and probably through exercise as well. Do not overdo it: extreme caloric restriction can actually damage the cell.
Can you measure autophagy in your body?
There is no reliable, simple method yet for measuring autophagy in your body. Scientists use combinations of indirect markers, but these are for now confined to research laboratories.
Can meditation do anything about ageing at the cellular level?
There are cautious indications that meditation favourably influences the activity of the telomere-repairing enzyme, but whether this truly keeps your cells younger has not yet been convincingly proven. Meditation for stress reduction has a considerably stronger evidence base in any case, and an indirect effect on cellular ageing via that pathway is plausible.
What exactly does senescence do to your cells as you age?
Senescent cells stop dividing, accumulate with age and cause damage throughout the body through a constant stream of inflammatory substances. They are both a protector (a brake on cancer) and a cause of damage, and that makes targeted intervention more complex than it appears.
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 exercise appears most beneficial; extremely excessive loading could actually dysregulate 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.