The relationship between stress and the gut-brain axis (GBA) is a two-way communication system. Stress impacts the GBA which in turn impacts the body’s response to stress. Stress leads to inflammation and increased gut permeability, hence making the entrails susceptible to pathogenic invasions. This causes a 'leaky-gut’ condition, allowing the harmful substances to enter the bloodstream. Inflammatory responses are triggered, leading to microbial imbalance. In chronic stress conditions, pathogens can completely colonize the gut, leading to a decrease in beneficial microflora, making the immune system weak.
The gut microbiota influences the brain’s response to stress via pathways involving the vagus nerve. The vagus nerve allows SCFAs (acting as signaling molecules), to directly affect the brain. Microbial products can affect cognition, stress response and mood. For example, GABA or gamma-aminobutyric acid, is a neurotransmitter that is linked to reducing anxiety. The presence or absence of these beneficial bacteria influences the neurotransmitter responsible for mood regulation, impacting stress and mental health.
Lifestyle and gut health are interrelated and very important for the overall well-being of an individual. The diet of an individual is very important to enhance the diversity of gut microbiota, and this can be achieved by including fiber and probiotics in the diet. Probiotic bacteria found in fermented food like sauerkraut, kimchi and yoghurt are beneficial for the gut. These foods can improve digestion, have anti-inflammatory properties, and further boost the immune system, lowering the risk of metabolic dysbiosis.
The quality of the gut microbiome is directly linked to immunity and metabolism. Microbes in the gut have anti-inflammatory effects and also account for better immunity and metabolism. Gut microbes affect metabolism as they ferment the fibers in our diet into short-chain fatty acids (SCFAs) like acetate, butyrate, propionate, etc. These SCFAs support the gut barrier, serve as a source of energy for colon cells, and help regulate lipid metabolism. Butyrate, for instance, strengthens the lining of the intestine, preventing pathogenic bacteria and substances from entering the bloodstream.
The short-chain fatty acids also have immunomodulatory effects. SCFAs reduce the release of pro-inflammatory cytokines and promote the release of anti-inflammatory molecules in order to maintain a good immune environment. This helps in preventing chronic inflammation, especially in the case of type 2 diabetes.
This dysbiosis can also lead to bile acid metabolism and reduced production of short-chain fatty acids. Imbalance in the gut microflora can impair fat digestion, promote oxidative stress, and lead to cardiovascular diseases. Thus, maintaining a good gut health is essential for preventing metabolic syndrome and promoting metabolic health. Various probiotic drinks such as ‘Yakult’ have been proven to improve gut health upon daily consumption.