Autophagy is a self-degradative process that is important for balancing sources of energy at critical times in development and in response to nutrient stress. Autophagy also plays a housekeeping role in removing misfolded or aggregated proteins, clearing damaged organelles, such as mitochondria, endoplasmic reticulum and peroxisomes, as well as eliminating intracellular pathogens. Thus, autophagy is generally thought of as a survival mechanism, although its deregulation has been linked to non-apoptotic cell death. Autophagy can be either non-selective or selective in the removal of specific organelles, ribosomes and protein aggregates, although the mechanisms regulating aspects of selective autophagy are not fully worked out. In addition to elimination of intracellular aggregates and damaged organelles, autophagy promotes cellular senescence and cell surface antigen presentation, protects against genome instability and prevents necrosis, giving it a key role in preventing diseases such as cancer, neurodegeneration, cardiomyopathy, diabetes, liver disease, autoimmune diseases and infections. This review summarizes the most up-to-date findings on how autophagy is executed and regulated at the molecular level and how its disruption can lead to disease.
What is autophagy?
Autophagy (pronounced “ah-TAH-fah-gee”) is your body’s process of reusing old and damaged cell parts. Cells are the basic building blocks of every tissue and organ in your body. Each cell contains multiple parts that keep it functioning. Over time, these parts can become defective or stop working. They become litter, or junk, inside an otherwise healthy cell.
Autophagy is your body’s cellular recycling system. It allows a cell to disassemble its junk parts and repurpose the salvageable bits and pieces into new, usable cell parts. A cell can discard the parts it doesn’t need.
Autophagy is also quality control for your cells. Too many junk components in a cell take up space and can slow or prevent a cell from functioning correctly. Autophagy remakes the clutter into the selected cell components you need, optimizing your cells’ performance.
Why is autophagy important?
Autophagy is essential for a cell to survive and function. Autophagy:
- Recycles damaged cell parts into fully functioning cell parts.
- Gets rid of nonfunctional cell parts that take up space and slow performance.
- Destroys pathogens in a cell that can damage it, like viruses and bacteria.
Autophagy plays an important role when it comes to aging and longevity, too. As a person ages, autophagy decreases, which can lead to a build-up of cellular junk parts and, in turn, cells that aren’t functioning at their best.
What happens during autophagy?
Autophagy-related proteins (ATGs) make autophagy possible. ATGs cause structures called autophagosomes to form. Autophagosomes carry the junk cell pieces to a part of the cell called a lysosome. A lysosome’s job is to digest or break down other cell parts.
Imagine lysosomes — part of a cell — eating other parts of the cell. The word “autophagy” is a combination of two Greek words translated to mean “self-devouring”:
- “Autos” means self.
- “Phagomai” means to eat.
Lysosomes eat the junk cell parts and then release the reusable bits and pieces. The cells use these raw materials to make new parts.
What causes autophagy?
Autophagy occurs when your body’s cells are deprived of nutrients or oxygen or if they’re damaged in some way.
Think of it this way: Autophagy is a recycling process that makes the most of a cell’s already-existing energy resources. The process ramps up when your body has to make the most of these resources because your cells aren’t getting them from an outside source.
With autophagy, a cell essentially eats itself to survive. The bonus is that this survival process can lead to cells that work more efficiently.
Can you induce autophagy?
You can induce autophagy by stressing your cells to send them into survival mode. You can induce autophagy through:
- Fasting: Fasting means that you stop eating for a certain amount of time. Fasting deprives your body of nutrients, forcing it to repurpose cell components to function.
- Calorie restriction: Restricting your calories means decreasing the number of energy units, or calories, your body consumes. Instead of depriving your body of calories completely (as with fasting), you limit them. This forces your cells into autophagy to compensate for the lost nutrients.
- Switching to a high-fat, low-carb diet: This type of diet, commonly referred to as a keto diet, changes the way your body burns energy, so that instead of burning carbs or sugar for energy, it burns fat instead. This switch can trigger autophagy.
- Exercise: Exercise stimulates processes that increase the activity of ATGs, such as stressing your skeletal muscles. Exercise can induce autophagy, depending on the type of exercise you’re doing and its intensity.
Still, being able to induce autophagy doesn’t mean you should. For instance, fasting, calorie restriction or switching to a keto diet may not be safe if you’re pregnant, breastfeeding or if you have a condition like diabetes. Similarly, you shouldn’t begin a vigorous exercise routine without consulting a healthcare provider.
How long do you have to fast for autophagy to occur?
Studies involving animals suggest that autophagy may begin between 24 to 48 hours of fasting. Not enough research has been collected on the ideal timing to trigger human autophagy.
Talk to a healthcare provider if you’re considering significant changes to your diet, like fasting. While fasting may be a good option for some people, it may put others’ health at risk. Don’t risk it.
What is the relationship between autophagy and disease?
Scientists once thought of autophagy as housekeeping — your cells’ way of tidying up to survive and function correctly. Within the past 20 years, scientists have discovered that autophagy may also play an important role in preventing and responding to disease.
What foods inhibit autophagy?
Interestingly, protein-based beverages may decrease autophagy activity. In a randomized control crossover trial, eight males were administered different protein/carb beverages after completing a 36-hour fast. A marker of autophagy activity (LC3II/LC3I ratio) was measured during the fasting vs. the non-fasting periods. A decrease in autophagy occurred when the men sipped on the protein-rich beverages (leucine-rich whey or soy-based protein) but not the carbohydrate-rich ones. The researchers noted that these findings align with rodent studies where branched-chain amino acids tend to suppress autophagy during catabolic conditions (like fasting). Glucose, on the other hand, does not impact autophagy.
Foods that promote autophagy
Lately, recent studies demonstrate that polyphenols, beneficial compounds found in plants, may play a role in inducing autophagy. Polyphenols stimulate various pathways, which can lead to autophagy and a longer lifespan.[3] For example, resveratrol is a common autophagy inducer found in grape skins and nuts. Other polyphenols include quercetin, green tea catechins, and curcumin. The following foods contain polyphenols that promote autophagy:
- Green tea
- Grape skin (red wine)
- Nuts
- Onions
- Apples
- Berries
- Turmeric
- Soybeans
- Milk thistle
A summary of what we know about autophagy:
- Autophagy is a form of cellular housekeeping in which misfolded proteins, damaged organelles, and pathogens are degraded and removed from cells.
- Autophagy plays a critical role in many areas of health, and like many physiological processes in the body, autophagy declines with age.
- Calorie restriction, fasting, and exercise are all potent inducers of autophagy.
- Polyphenols, beneficial compounds found in plants, may also play a role in inducing autophagy.
- Only a handful of studies measuring fasting and autophagy exist in humans. More research is needed to fully understand the benefits and implications of autophagy. Thanks https://my.clevelandclinic.org/,https://www.ncbi.nlm.nih.gov/,https://www.frontiersin.org/
