Maintaining health of the colon Part 2
Functions of the normal gut flora
Ordinarily, bacteria are known to be harmful to man, but what is referred to as the normal gut flora is actually beneficial to the human being. They are a complex community of bacteria situated especially in the colon and maintain a mutually beneficial relationship with the human host; a symbiotic kind of relationship. Their presence in the colon has a lot of physiological and health benefits to man.
Functions of the normal gut flora
1. Destruction of other pathogenic bacteria
Unfriendly bacteria as they are called, are pathogenic bacteria that can cause infection in the colon if left unchecked. It is the responsibility of the normal gut flora to defend the host against these bacteria. They do this by taking up all the space available. As they increase in number, they also use up all available nutrients thereby starving the invading organisms of nutrients. They could also secrete certain compounds that either kill or inhibit these unfriendly bacteria.
2. Metabolic activities
Usually, undigested food particles get to the colon from the small intestines. Food is normally digested and absorbed in the small intestines. It is not all the time that this digestion and absorption of food is complete in the small intestine. Apart from being completed, there are certain types of nutrients that are not digested in the small intestine.
These are some nutrients like long chain carbohydrates such as polysaccharides, starch, fibre and some amino acids and proteins. These are all metabolized in the colon by the normal gut flora. If the enzymes that are involved in the metabolism of these undigested substrates are deficient, these undigested foods will begin to undergo a process of putrefaction; they begin to rotten.
The end result of this process is the generation and release of toxins and acids. When these toxins and acids accumulate in the colon, disease could arise in the colon or elsewhere further away from the colon. The most serious of this is cancer. A common metabolic disease known as lactose intolerance occurs as a result of lactase deficiency. Lactase is the enzyme that should act on lactose to break it down to glucose. In lactose intolerance, there is deficiency of lactase and undigested lactose accumulates in the intestines. In such a case, the normal gut flora releases enzymes that will break down the lactose.
The end products of these metabolic activities in the colon are short-chained fatty acids such as acetic acid, butyric acid and propionic acid. These products can be absorbed by the cells and into the circulatory system and used to produce more energy and nutrients for the body. Acetic acid is a substrate for energy generation in the muscles while butyric acid produces energy in the cells of the intestine. Propionic acid helps to produce ATP in the liver.
Other metabolic functions of the gut flora include enhancing the absorption of minerals such as magnesium, calcium and iron. They also help in the absorption and storage of lipids and they produce and enhance the absorption of vitamin K, vitamin B12 and folic acid. In all the actions of the gut flora, they prevent the production and accumulation of acids. As they do so, they can be said to prevent cancer.
3. Immune enhancing function of the gut flora
The wall of the intestine has three layers and these are the epithelium, the lumina propia ànd the muscularis mucosae. Within the intestinal epithelium are goblet cells, which produce and secrete the intestinal mucosa barrier. The normal gut flora attaches themselves to this mucosa barrier and feed on it. On the other hand, the barrier prevents microorganisms, toxins, acids and antigens from penetrating.
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