Our entire digestive tract is lined with a barrier made of mucus membranes that protects the gastrointestinal (stomach and intestine) cells. This layer is made up of sugar and protein molecules called glycoproteins.
Microbes actually loooove to eat sugar... so, why don't the ones in our guts eat away at these glycoproteins?
Well our immune system prevents this from happening and sends out proteins that monitor and protect our mucosal membranes and tag microbes as "beneficial" or "pathogenic/harmful" to our gut lining. This way our immune system knows which microbes to spare and which ones to kill.
Feeding our microbiome a diet rich in fibrous foods and prebiotics gives the microbes something to eat instead of eating the glycoproteins that protects our gastrointestinal cells!
Our bodies actually cannot break down fiber into nutrients we can absorb so we rely heavily on our gut microbiome to do this for us and in return, our microbiome thrives!
FIGURE: When our bacteria do run out of good food and fiber to eat, or there is an imbalance between the bacteria in the gut, they will start to eat away and degrade the mucosal layer that protects our cells. This makes the cells (grey boxes in the graphic) more susceptible to infections, causes inflammation and can lead to chronic disease.
This causes the tight junctions between the cells to become weak from the penetrance of pathogenic microbes (the yellow guys). This causes leaky gut which can impair nutrient absorption and digestion. These microbes also release gaseous byproducts when they break down the the mucosal lining which is the reason we get bloated and gassy. So, a healthy gut environment means: good poops, little to no gas, confident signals to the brain signaling hunger, satiety, fullness and overall feelin naturally energized and happy!
This is why it's important to consume enough fiber in your diet and protect this mucosal barrier in our gut! Men should get 35-40g of fiber daily and women 25-35g. Personally I strive for around 30g daily and that helps your GI system stay healthy and regular!