Numerous studies have found that functional foods promoting autophagy -- a regulated mechanism that enables the removal of dysfunctional or unnecessary cell components -- can prevent or treat chronic diseases, as well as support optimal health and delay cellular aging.
These benefits of functional foods are attributed by scientists to their bioactive components. Today, the demand for functional foods is increasing due to the rising prevalence of chronic diseases, such as obesity, diabetes, cardiovascular disease and neurodegenerative diseases.
Recognizing this, researchers at Wuhan Sports University in China decided to explore the mechanisms employed by the bioactive components of functional foods to exert their health-promoting effects. They focused particularly on how these mechanisms are related to autophagy, as dysfunctional autophagy has been linked to the onset of many chronic or age-related diseases.
Autophagy and chronic diseases
Metabolism is a crucial part of autophagy and serves as a regulatory factor for three vital sources of energy for cells, namely glucose, fats and protein. When metabolism of these three energy sources is dysregulated, it results in high blood sugar levels and the formation of protein aggregates and lipid droplets, all three of which have been identified as contributors to chronic diseases.
In contrast, enhanced autophagy helps degrade these harmful substances, inhibiting disease development. Here's how autophagy works against metabolic and age-related diseases, according to literature.
Diabetes
Characterized by high blood sugar resulting from insulin deficiency or insulin resistance, diabetes mellitus is primarily linked to beta-cell dysfunction or death. Beta-cells, or insulin-producing cells, are highly susceptible to oxidative stress, which can impair their function. Induced autophagy has been found to protect against oxidative stress, especially in insulin-associated tissues, such as the liver, adipose tissue and skeletal muscles.
Obesity
Obesity is associated with an accumulation of lipid droplets, protein aggregates and damaged mitochondria, which are targets of autophagy. However, studies have found that in obese patients, autophagy is suppressed by excessive nutrition, which inhibits the activation of important signaling pathways. Therefore, enhancing autophagy will not only get rid of these harmful substances, but it will also reduce the excessive inflammation and fat formation that are the root causes of obesity.
Cardiovascular disease
Reduced blood flow to the heart is caused by the partial or complete blockage of coronary arteries. This event causes cardiac ischemia, a condition marked by the reduced ability of the heart muscle to pump blood due to injury. But during autophagy, free fatty acids and amino acids, which are essential for the survival of heart muscle cells, are released. Hence, promoting autophagy during cardiac ischemia can protect the heart from further injury and prevent life-threatening complications, such as heart attack or heart failure.
Neurodegenerative diseases
The accumulation of protein aggregates in the brain has been found to impair the function of neurons, damage their components and ultimately cause their death. That's why protein aggregates are believed to be the root cause of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease and Huntington's disease. On the other hand, autophagy is a natural process designed to get rid of such harmful products, so inducing autophagy will greatly help alleviate the pathological symptoms of neurodegenerative diseases.
Functional food components and autophagy
According to studies, the bioactive components of functional foods possess many beneficial properties, such as antioxidant, anti-inflammatory, hypolipidemic (cholesterol-lowering), blood sugar-regulating and neuroprotective properties. Many of these components are also capable of regulating the functional status of autophagy. Here are a few examples:
- Resveratrol -- Typically found in berries, nuts and grapes, resveratrol is said to activate autophagy by activating a protein called Sirt3 and an enzyme involved in cellular stress responses.
- Epigallocatechin-3-gallate -- A polyphenol found in green tea, EGCG is particularly useful in stopping the progression of metabolic diseases. By inducing autophagy, EGCG reduces lipid accumulation in blood vessels and suppresses the accumulation of lipid droplets.
- Curcumin -- The main active component of turmeric, curcumin activates autophagy by increasing the expression of Bcl2 and Bax, two proteins that promote cell survival.
- Trehalose -- A sugar produced by microorganisms like fungi and yeasts, trehalose has been found to induce autophagy and promote the survival of cells after exposure to hydrogen peroxide. Trehalose-induced autophagy has also been found to decrease tau protein levels in the brain, suggesting a neuroprotective effect against Alzheimer's.
Many plant-based foods are functional foods capable of enhancing autophagy. These include fruits, vegetables and herbs, which are not only rich in essential nutrients but are also abundant in bioactive components. To prevent chronic diseases or address their symptoms, incorporate autophagy-inducing functional foods like turmeric, green tea, berries and nuts to your daily diet.
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