The human intestine is the natural habitat for a series of microorganisms that make up the intestinal flora, which consists of around 100 billion bacteria from 500-1000 different species. Humans acquire this intestinal flora over time. We are born sterile and, from the time we enter into contact with our environment, we acquire these microorganisms that dwell and proliferate in the entire digestive system.
Anatomically, the inside of the mouth, stomach and intestines are considered external parts of the body as they are in contact with the environment. The main function of the bacterial flora is to cover all parts of the digestive tube that are in contact with the external environment.
The majority of these microorganisms are in the colon, because the stomach and first sections of the small intestine contain an acidic level that creates an invisible habitat for the majority of microorganisms.
Intestinal flora is not the same for each person, and flora will change in each person depending on the multiple variables affecting them: type of diet, stress level, medication, geographical area in which they live, etc.
Some of the microorganisms making up the intestinal flora have damaging effects on health. If the number remains low in comparison with those with positive benefits, there will rarely be undesirable effects. However, when the proportions are unbalanced, the beneficial functions of the intestinal flora will change.
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The main functions of intestinal flora are:
- A barrier effect, preventing germs and pathogens that arrive from food waste from entering
- Synthesis of vitamin K and vitamin D
- Energy production, for both the body and bacteria
- Absorption of calcium, magnesium, sodium and partly iron
- Immune protective functions. Intestinal mucus is an area for interface between the environment and the immune system. The intestinal lymphoid tissue contains the highest concentration of immune competent cells in the human body