Intestinal bacterial flora
To best perform its metabolic activities, the digestive system requires the presence of a series of bacteria, known by the name of “intestinal microflora”, that promote the processes of transit, absorption and transport. There are many scientific studies that have found an increased risk of certain diseases in people who have impaired intestinal flora.
Composition of the microflora
The gastro-intestinal tract of the human being is able to contain on average 300-500 different species of bacteria. The majority of the bacteria is localized in the lower part of the intestine (colon). The scarcity of bacteria in the stomach and upper intestine is due to the high presence of corrosive substances (acids, bile and pancreatic secretions), making the habitat unsuitable for the survival and proliferation of these microorganisms. Unfortunately, among the bacteria that survive the acidic environment there is one organism, Helicobacter pylori, responsible for gastric ulcers.
The colonization of the intestine by these bacilli begins at birth and is completed within a few days. To alter the composition and quantity of the bacterial flora of the newborn is the type of delivery (natural or cesarean), the power received (breast or formula) and the surrounding environment. This explains why, with advancing years, the intestinal flora can change, even considerably.
By bacteriological examination of the stool and the bacteria culture was highlighted a prevalence of anaerobic bacteria (which can survive or even only in the absence of oxygen) than aerobic (which need oxygen to stay alive).
Among the first group of bacteria in the intestine are the bifidobacterium, the Eubacterium, Clostridium, the Peptococcus, the Peptostreptococcus and Ruminococcus. Among the bacteria of aerobic type, however, they have been identified, among others, Escherichia, Enterobacter, the Enterococcus, Klebsiella, Lactobacillus, and Proteus.
The main functions
The intestinal bacterial flora is a real microbial-barrier enzyme able both to protect the organism from any harmful microorganisms, and to break down the elements of transit in smaller and smaller parts so as to make available the vital factors, such as vitamins, minerals and all the micronutrient requirements.
According to investigations conducted on laboratory animals specially deprived of intestinal bacteria, the role of bacterial microflora seems to be summed up in three main functions: metabolic, trophic and protective.
metabolic function: fermentation of the non-digestible dietary remaining and intestinal endogenous mucus; energy recovering in the form of short-chain fatty acid; production of vitamin K and control ion’s absorption;
trophic function: control the proliferation and differentiation of epithelial cells; development and homeostasis of the immunity system;
protective function: barrier effect against pathogens.
When you have an alteration of bacterial flora (for stress, food disorders, taking drugs or diseases), then, to suffer it is the whole organism; in particular, these imbalances can lead to a reduction of enzymes and immunoglobulins IgA, substances to the base of the immunity system present in the intestine and concentrated in the lymphatic stations, called “Peyer’s patches”, which represent at least 65% of the immune potential of the organism. From here the risk of excessive proliferation of fungi and pathogens, as well as increased exposure to diseases, even serious. In particular…
… Colon cancer
Although it seems to be certain now the great weight of the genetic predisposition in the development of colon cancer, in some cases, the perpetrators of the disease seem to be the feeding and a wrong lifestyle. It is not new, in fact, that the high consumption of red meat and fats can increase the risk of colorectal cancer and that, on the contrary, the regular intake of fruit, vegetables, fish and cereals is able to reduce the incidence of the disease. According to experts, the link between risk of intestinal cancer and incorrect feeding would depend just by the alteration in the composition of the intestinal flora, which could also favor the development of carcinogens, and cocarcinogeni procarcinogens, substances that are able stimulate a cell proliferation in neoplastic sense .
From an analysis of the feces of healthy subjects who followed a diet high rich in fat and low in fruits and vegetables has, in fact, resulted an increase of the concentration of N-nitroso- compounds, substances known to be at the base of the development of the colon cancer .
… Intestinal inflammatory diseases
Even for the inflammation of the intestine, in addition to possible genetic reasons, it seems to play a role also the alteration of the bacterial flora. In particular, many cases of ulcerative colitis and Crohn’s disease (the most common forms of bowel inflammation) would seem to depend precisely by poor intestinal production of IgA and IgG (another type of immunoglobulin), whose reduction would be caused by an alteration of the bacterial microflora.
Consequently, the intestine has difficulties to protect itself from the attack of harmful agents, bacteria and substances escaped to the digestion and it puts in action particular cellular automatisms of inflammatory response turned to the elimination of aggressive factor; these mechanisms, in the long run, would lead just to a chronic inflammation of the intestine.
To the probiotics and prebiotics studying
To prevent these and other intestinal diseases, currently the medical and scientific research is now targeting the probiotic bacteria and prebiotics, or about the bacteria considered beneficial to human health. In particular, the term “probiotic” is referred to bacteria that, once ingested, are able to arrive alive and active in the intestine, without being destroyed by bile salts, or by the gastric juices; with the term “prebiotic”, instead, They are indicated those compounds capable of stimulating the development of “good” bacteria present in the colon. The combination of probiotics and prebiotics is also known as “symbiotic combination.”
Numerous studies on laboratory animals have shown that the addition in the diet of probiotics and prebiotics is able to reduce the development of colon cancer. In humans, however, there are still no firm evidence of this possible protective effect. It was, however, already amply demonstrated that the probiotic bacteria are able to contrast the production of carcinogens, and co-carcino-gens pro-carcinos.