The Importance of Our Gut
Our gut microbiome is a critical component of digestion, breaking down complex carbohydrates, proteins, and to a lesser extent fats for assimilation and sometimes producing substances to help maintain our health and the health of our microbiome. Microbiome digestion and fermentation of what we eat results in a multitude of microbial metabolites that can act both locally and systemically (after being absorbed into the bloodstream). The impact of these produced biochemicals on our health is complex, as can either be beneficial (butyric acid, acetic acid) or potentially harmful (hydrogen sulfide gas, ammonia).
The Human Gut Microbiota
The human gut microbiota is a complex ecosystem of microorganisms that inhabits and critically maintains homeostasis of our gastrointestinal tract. In general, microbial metabolism of both exogenous and endogenous substrates make them usable by us. For example, probiotic bacteria in our digestive tract can help break down lactose by producing the lactase enzyme for people who are lactose intolerant and lack proper lactase production. Microbial metabolites can also act to modulate the immune system through impacting the physiology and gene expression of host cells, which can help form our immunity when we are young or help control it hopefully for the better when we are adults.
The colon is the major site of bacterial fermentation, as its relatively high transit time and slightly acidic pH coupled with low cell turnover and redox potential presents more favorable conditions for dysbiosis when digestion efficiency is poor in parts of the digestive tract before it. For example, the small intestinal microbiota (though in smaller amounts than the colon) has been shown to regulate nutrient absorption and metabolism conducted by the host. Further, the presence of diverse metabolic activity can allow the microbiota to maximally fill the available
ecological niches and competitively inhibit colonization by pathogens at all sites
throughout the digestive tract when you are health.
Microbiome Affecting Your Gut Health
The microbiome can also affect gut health and may play a role in intestinal diseases like the development of dysbiosis (LIBO or SIBO) and inflammatory bowel disease. bloating, cramps, and abdominal pain that people with inflammatory bowel disease experience may be due to gut dysbiosis (Mycobacterium avium paratuberculosis overgrowth). Symptoms of IBD occur because the microbes produce a lot of gas and toxins, which contribute to the symptoms of intestinal discomfort, strong immune reactions, and inflammation.
The gut microbiota play important roles in lipid metabolism and absorption. A study showed that conditioned media from specific bacterial strains directly upregulate lipid absorption genes in murine proximal small intestinal epithelial organoids. These findings indicate that proximal gut microbiota play key roles in host adaptability to dietary lipid variations through mechanisms involving both the digestive and absorptive phases and that these functions may contribute to conditions of overnutrition and undernutrition.