Friendly Bacteria – Probiotics

Submitted By: Katarina Horakova, Dr.Sc.
The micro-flora of a digestive tube contains a very diverse group of micro-organisms, which includes more than 400 different types of bacteria. The number of bacteria is increasing. While there are about 103 per ml of them in stomach, there are as much as 105-106 per ml of them in small intestine; and the biggest number is to be found in colon - there are more than 1012 per ml.

Gut flora is very important for the functioning of digestive tract and for the supply of nutrients. Its role in colon is to ferment food elements which cannot be decomposed in small intestine. They include resistant starch, non-starch polysaccharides (fibre), oligosaccharides, proteins, etc.

About 60 to 80 g of food gets into a colon of an adult daily.

In the first part of colon the food is partially decomposed into lactic acid and short-chain fatty acids (such as acetic acid, propionic and butyric acid) thanks to the activity of bacteria, for example the representatives of genera Bifidobacterium and Lactobacillus. These acids have positive effects on the host organism. They provide energy to epithelial cells of colon, decrease pH, increase the absorption of calcium, iron and magnesium; and improve metabolism of glucose and lipids in liver. Other substances (carbon oxide, hydrogen, methane, phenolic compounds, amines and ammonia) also come into existence during the process of decomposition. However, phenolic and nitrogen compounds arise only in its downward part (descending colon) and S-shaped part (sigmoid colon), where many diseases may develop, e.g. colon cancer and ulcerative colitis.

Health benefits of lactic acid bacteria - probiotics

"Good" bacteria, mainly bacteria of lactic acid fermentation, are very important to keep our body healthy. The name refers to their ability to ferment lactose and several other sugars into lactic acid (and various organic acids). Lactic acids belong to the category of micro-organisms which keep microbial balance in our body; that is why they are called friendly bacteria - probiotics.

* Due to the production of lactic acid they decrease pH of the environment, which becomes acidic and thus unfavourable for bacteria.

* Their ability to produce bacteriocins - peptides and proteins with qualities of antibiotics is also very important. In this way they prevent pathogenic and putrefying bacteria from multiplying.

* Apart from this, they produce vitamin K, perform dehydroxilation and deconjugation of bile acids. In this way they decrease their ability to modify into faecal bile acids, which contribute to the development of colon cancer.

While common gut bacteria are able to live long and multiply in digestive tract; probiotic is a live bacterium, which stays in it only for a short period. Here it performs beneficial activities, but is unable to colonize in the long term. It means that it's necessary to take probiotics over a longer period of time in order to feel their positive effects.

Bifidobacteria (Bifidobacterium lactis, Bifidobacterium longum, Bifidobacterium breve) and lactobacilli (Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus bulgaricus etc.) are among lactic acid bacteria which are most commonly used. These beneficial lactic acid bacteria can be found mainly in fermented dairy products. Yoghurts with live probiotic cultures, cottage cheese, but also non-pickled sauerkraut have curative properties. At the moment there are also many other ways how to supply our guts with beneficial bacteria, mainly in the form of high-quality dietary supplements. Probiotic products, live bacteria of which have the form of freeze-dried capsules and thus can resist acidic environment in stomach, are among the most stable ones.

The composition of micro-flora changes during the lifetime

Immediately after the birth our digestive tube is sterile and bacteria settle in the tube gradually during breast-feeding; later they get into our body through the contact with the environment and food consumption. During the aging process the composition of gut flora changes considerably. Older people have lower or zero number of bifidobacteria; while the number of lactobacilli, enterococci, enterobacteria and clostridia increases. This can lead to the accumulation of pathogenic and toxic substances, development of colon cancer and liver disorder. It was found out that if the number of undesirable bacteria is higher than the number of probiotics, the risk of developing a wide range of diseases increases significantly. They include for example:

* Irritable bowel disease
* Inflammatory bowel disease (Crohn's disease, ulcerative colitis)
* Colon cancer
* Gastroenteritis (inflammation of stomach and small intestine)