The term "autophagy" describes a small miracle of nature: the self-renewal of our cells. Find out how this amazing process works.
Table of contents
1. What does autophagy mean?
The term autophagy , or autophagocytosis, comes from ancient Greek and means " to consume oneself ." Autophagy refers to the natural process of cell renewal , cleansing, and regeneration.
We now know that this process occurs in almost every multicellular organism . Autophagy therefore performs an unprecedented function for our bodies.
Nevertheless, we haven't actually known about it for very long: Yoshinori Ōsumi first intensively researched the functioning of this process in the 1990s [1]. The phenomenon was discovered by Christian de Duve in 1963.
Since we did not yet know exactly how autophagy actually works and how it is triggered until Ōsumi's research, the Japanese scientist was awarded the Nobel Prize in Medicine in 2016 for his research.
Thanks to Ōsumi, we know that autophagy recognizes damaged cell structures and subsequently breaks them down into tiny building blocks . These building blocks are then either reused or degraded through metabolism.
Cells that are recognized and reorganized during autophagy include defective proteins or other defective cellular elements . If these can no longer be used to build new cells, our organism often uses them as fuel [1].
In this sense, the autophagy process is very similar to energy production from fat reserves , which is triggered by a calorie deficit: Without a calorie and energy deficit, both fat and cellular waste accumulate. In the long term, such "cellular waste" can impair the functioning of the affected cell(s) [2].
The primary goal of autophagy is to protect the organism from pathogens and to conserve energy during periods of hunger or other physical stress. Autophagy also plays a central role in certain diseases such as cancer, Parkinson's disease, and diabetes.
2. When does autophagy begin?
The exact moment at which autophagy actually begins or develops its full effect is not yet scientifically clear . However, autophagy generally begins when our insulin levels remain consistently low [3].
This signals to our body that it doesn't have enough energy available. In response , the lack of new energy sources causes it to eventually draw on old reserves .
The first port of call is almost always the glucose stores in the muscles or liver. Once these are used up, the body turns to the energy reserves in our fat cells .
If insulin levels remain low , the breakdown or recycling of damaged cell structures eventually begins. This process can begin as early as 12 to 16 hours , although scientists are not yet clear on the exact timing.
While autophagy may well begin after 12 hours, its full effect only unfolds after a constant insulin drop of approximately 48 to 72 hours . For this reason, fasting lasting several days or a drastic calorie restriction are considered top triggers for cell renewal [4].
3. Autophagy and fasting
In light of the above, the connection between autophagy and fasting is actually almost clear: fasting is accompanied by a strong calorie reduction , so it is generally regarded as one of the safest stimuli for autophagy [5].
However, how long and under what conditions fasting is necessary is not 100% clear. While proponents of 16-hour intermittent fasting often claim to have an autophagy effect , others assume that only a drastic calorie reduction over at least three days can be effective. A final verdict can only be provided by further research in this area.
However, things are different with traditional therapeutic fasting : Here , only 500 kcal are consumed per day over a period of 3 to 21 days . This type of fasting very likely leads to a stimulation of autophagy .
In order to enjoy the full effect of cell renewal, the fasting cure should last at least 3 days , i.e. 72 hours.
Too much of a good thing? No problem: So-called "pseudo-fasting" also offers excellent opportunities for autophagy. Just like therapeutic fasting, only a few calories are consumed over a period of several days.
Unlike other fasting regimes, you can eat a little more with 750 kcal per day on at least five fasting days. The starting point when choosing a fasting regime should always be to weigh the calorie reduction against the number of fasting days.
Anything lasting 72 hours or more and with a calorie intake of less than 750 kcal per day could be an effective stimulus for cell regeneration.
4. Foods for autophagy
First things first: Even autophagy should n't cause you to forgo a nutrient-rich diet . After all, on your fasting days, you generally need to consume a certain number of calories to stay healthy.
In fact, there are even certain beverages and foods that may have a beneficial effect on autophagy ! The biogenic polyamine spermidine plays a particularly important role.
Although it is produced in our bodies , it can also be absorbed through certain foods. Cheese , soybean germ , mushrooms , and wheat germ, in particular, contain high amounts of the polyamine.
Another classic autophagy trigger is black coffee – or at least coffee without animal milk products .
5. Conclusion
The term autophagy refers to the natural renewal and recycling of damaged cells . This phenomenon thus performs an incredibly important self-cleaning function, making it almost a small natural miracle.
To trigger the process of autophagy, a calorie deficit must be created so that insulin levels remain consistently low for approximately 72 hours . Therapeutic and sham fasting are particularly suitable for achieving this state.
Popular fasting methods like interval or intermittent fasting, however, aren't always sufficient. However, you can also give your cellular detox an effective additional boost with certain foods.
These include milk- and sugar-free coffee, as well as foods rich in spermidine. Besides cheese and mushrooms, these include soy and wheat germ.
6. Sources
[1] Mizushima, N.; Levine, B. (2010), Autophagy in mammalian development and differentiation, Nature Cell Biology, Volume 12, Issue 9, p. 823-830, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3127249/.
[2] Sedwick, C. (2012), Yoshinori Ohsumi: Autophagy from beginning to end, Journal of Cell Biology, Volume 197, Issue 2, p. 164-165, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3328387/.
[3] Bagherniya, M.; Butler, A.E.; [...]; Sahebkar, A. (2018), The effect of fasting or calorie restriction on autophagy induction: A review of the literature, Aging Research Reviews, Volume 47, p. 183-197, https://www.sciencedirect.com/science/article/pii/S1568163718301478?via%3Dihub.
[4] Ribeiro, M.; López de Figueroa, P.; [...]; Caramés, B. (2016), Insulin decreases autophagy and leads to cartilage degradation, Osteoarthritis and Cartilage, Volume 24, Issue 4, p. 731-739, https://www.sciencedirect.com/science/article/pii/S1063458415013709.
[5] Galluzzi, L.; Pietrocola, L.; [...]; Kroemer, G. (2014), Metabolic Control of Autophagy, Cell, Volume 159, Issue 6, p. 1263-1276, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4500936/.
