Probiotics – the healthy bacteria that bring us only benefits

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Some bacteria are a true friends of us humans… For millennia, humans instinctively know that food transformed under the action of microorganisms have positive health effects . In Eastern Europe , Russia and the Middle East where fermented products for hundreds of years are consumed , it has always considered that these foods are a source of health and longevity.

It is, however, that for forty years that scientists are very interested to bacteria and yeast in them. And especially to those who have health effects called probiotics.

What Are Probiotics?

Probiotics‘ are live bacteria or yeast from the diet which, according to the official definition, ” ingested in adequate amounts , rebalance our intestinal flora and have a positive effect on health.” For Gary Huffnagle , a leading personality in the field of probiotic research (University of Michigan , USA ), ” current research shows that there many benefits to having a diet rich in probiotics .” But is not that probiotic wants. The bacteria must have proven their health benefit to deserve that name !

A treacherous journey from the mouth to the colon

Before acting, probiotic bacteria should live tru a great trip: be swallowed withstand stomach acid and digestive enzymes , pass through the small intestine to reach after 4-6 hours of travel , the terminal part of the digestive tract , the colon. An obstacle course in which many bacteria will leave their skin.

Once in the colon, probiotics fit into the intestinal flora, are all the nutrients they need, multiply … and make their benefits !

What Is The Intestinal Flora?

To understand the principle of action of probiotic bacteria, we must first know that 100,000 billion bacteria belonging to 400 different species , each with their own characteristics, already inhabit our intestines. It is what is called ” intestinal microflora ” or ” microbiota .” It is within it that probiotics will integrate and act.

These bacteria are 10 to 100 times higher than the cells of our body to a mass of about 1 kilo! All micro -organisms that live flora in balance with each other and together form an ecosystem .

Problem to study the operation of the plant : 80% of bacteria that are said to constitute “strict anaerobic ” , in other words, they can not tolerate oxygen. In addition , they have nutritional requirements as their laboratory culture is impossible. Their nature and function are therefore poorly understood by scientists.

How Do Bacteria In The Intestinal Flora Did They Get In The Gut?

Bacteria come in the digestive tract mainly through food . At birth , the baby is completely sterile . In contact with the mother and the environment and food, the digestive tract is gradually brought into contact with germs from the outside. From childhood to adulthood , according to the Food and experiences, a number of bacteria are going to live primarily in the large intestine , the terminal part of the digestive tract called the colon.

Each individual has his own collection of bacteria that is different from its neighbor. “Recent studies comparing the composition of the fecal bacterial microflora show that adults 10 adults rarely have more than one bacterial species in common , even if they eat the same way , says Gerard Corthier researcher at the Unit ecology and physiology of the digestive system of the National Institute of Agronomic Research ( INRA ) . The composition of the flora us is very personal, like our fingerprints ! ”

Where Are These Bacteria Used?

Fermentation is a part, with smoking or salting, traditional means of food preservation . These allowed the time to store food in times of plenty to deal with lack during periods less pomp .

Lactic acid bacteria are bacteria most commonly used in these fermentations. They acidify the environment by producing lactic acid and thus prevent pathogenic microorganisms from growing.

Today, the manufacturing process of many foods involve fermentation. This is the case of beer , wine , vinegar, tea, coffee, chocolate , bread, soy sauce … However , most of the time the bacteria is killed during cooking, roasting , sterilization or removed before distribution (clarification of wine, vinegar , beer , soy sauce , etc.).

You will find in the table below are some fermented foods that are sold and consumed with their bacteria. But be careful ! These bacterial strains are not necessarily probiotics and must have demonstrated health effects to receive this designation.

yoghurt photo


Lactobacillus bulgaricus

Streptococcus thermophilus

Actimel fermented milk

Lactobacillus casei defense

Fermented milk Activia

Essensis active bifidus

LC1 fermented milk

Lactobacillus casei

Yakult fermented milk

Lactobacillus casei Shirota

Fermented milk B’A



Lactobacillus plantarum

Sausage (and sometimes smoked salmon )

Lactobacillus sakei



White (light) beer 

Saccharomyces cerevisiae

A “living” yeast called boulardii yeast (sold in health food store , not to confuse ordinary beer yeast rendered inactive by drying at high temperature)

Saccharomyces boulardii

Kefir fruit ( in health food store or on the Internet , particularly on the ebay website)

Lactobacillus caucasicus

Streptococcus lactis

Kefir milk (ditto)

Lactobacillus bulgaricus caucasicus

Bulgaricus Lactobacillus casei

Streptococcus lactis

Streptococcus diacetylactis

Leuconostoc citrovorum

Saccharomyces kefir

Fermented milks are highly concentrated bacteria. One gram of yogurt actually contains 10 million bacteria. As much as a gram of sausage or a gram of cheese. However, to improve its contribution to bacteria, it is easier (and less calories ! ) To eat 100 grams of yogurt daily rather than 100 grams of meat or 100 grams of cheese.

Another possibility to supply its intestinal flora bacteria : Consume probiotics in the form of dietary supplements : capsules containing a specific number of bacteria or CFU ( colony forming units ) . For yeast Saccharomyces boulardii , there are yeast “active” which contains living microorganisms.

Be careful though ! A recent report on the U.S. site ( an independent evaluation of health products ) reveals that many probiotic capsules , such as those found in the trade, contain a lower number of live bacteria announced that on packaging and especially insufficient to make any effect. ( )

Flora, An Ecosystem Off Balance

The flora is constantly in motion. At any time , bacteria are born, others die . And most importantly, constantly coming up with new foods. Yoghurt, cheese, raw sauerkraut and sausages and all fermented foods provide large quantities . Any fresh fruit or vegetable is also has a very large number on its surface .

The so-called “endogenous resident” bacteria are bacteria flora particularly well suited to conditions in the digestive tract. They are more numerous but also more stable. These include two types of bacteria “dominant” and ” subdominant “.

Besides the resident flora are the so-called ” transition ” that merely pass through the digestive tract flora. This is the plant that probiotics belong. It is for this reason that to maintain the effect of a probiotic , it must continue to consume .

Among the species ‘ sub- dominant “and” pass ” , there are potentially pathogenic bacterial microorganisms but , normally , do not multiply . Why ? With the dominant flora . It has a strong enough that unwanted bacteria can develop demographic pressure.

How to build the balance of flora ? Various forces clash. The growth of a bacterial strain will be limited by the “food” available. If the substrate it needs to live is coveted by others, there is competition and automatically growth is thereby limited. There may also be competition for binding sites on the intestinal wall . Some species will also synthesize metabolites that may be toxic to other members of the flora. Some bacteria can also communicate with each other by exchanging chemical messages that can affect their metabolism . Sometimes inhibit their development, sometimes to stimulate . In short, the intestinal flora is a place of intense life governed by subtle interactions that lead to an overall delicate balance.

Some factors may affect the species present in the flora and thus the prevailing balance between them. More power is , for example, rich in indigestible fiber , most bacterial species that are fond will be able to multiply and there will be less room for others. The arrival of new bacteria such as probiotics may improve the functioning of the ecosystem. However , stress , fatigue or illness can disrupt the balance and destabilize the flora.

Pro- , Pre- And Sym – Biotic , What Is The Difference?

Probiotic  is called a microorganism that is able to rebalance the intestinal flora and have a positive effect on health. A prebiotic is a non- digestible food ingredient ( indigestible fiber , fructo -oligo -saccharides … ) which has a beneficial effect on health by selectively stimulating the growth and / or metabolic activity of one or a limited number of gut bacteria . Is a symbiotic combination of a probiotic and a prebiotic .
Antibiotics can also be devastating especially when they affect the dominant strains effects. If they are weak, they are no longer able to exert pressure on the sub-dominant pathogenic strains that will begin to proliferate and cause gastrointestinal infections or diarrhea.

What Is The Role Of Plants In Human Health?

The intestinal flora plays three key roles for health:

– First, a nutritional role . In attack the foods that have not been digested , it shall degradation by fermentation. Some metabolites from these fermentations , including short-chain fatty acids ( fatty acids link to file ) , are beneficial to health. Bacteria also help detoxify certain nutrients. INRA researchers have also shown that glucosinolates , substances found in plants of the mustard family (cabbage, turnip , cauliflower … ) are converted by intestinal bacteria into molecules that have anti – carcinogenic , especially isothiocyanates against colorectal cancer. Some bacteria are able to synthesize vitamin K essential for blood clotting .

The then – flora plays a role as a barrier against pathogens by preventing them from attaching to the intestinal wall by different mechanisms : either by competition between bacteria ( for the same substrates for the same receptor sites on the wall … ) by the production of substances harmful to pathogens ( antibiotics, bacteriocin … ) or by the formation of an unfavorable environment for their development ( too acidic or too rich in harmful substances). Some bacterial species of flora can also act on the vital genes pathogens prevent them from feeding or breeding.

– Finally flora plays a fundamental role in the “education” and boosting the immune system. The intestine contains many immune cells than any other immune organs combined ( thymus , spleen , bone marrow , lymph and blood) . GALT the intestinal immune system is known to Gut- Associated Lymphoid Tissue . It is considered the first immune organ of the body. It has an ambiguous task as it must at the same time react against pathogens but tolerate food and microorganisms constantly present in the digestive substances. The plant will stimulate the GALT by teaching him to recognize the harmful organisms against which it must respond. It also modulates immune responses , the term ” immunomodulator “. ” Role in rare and poorly known conditions , it happens that this immune stimulation is excessive and causes certain inflammatory bowel diseases or IBD ( such as ulcerative colitis and Crohn’s disease ) says Gerard Corthier researcher at INRA . In this case the individual no longer tolerate his own gut flora and inflammatory lesions appear where the microorganism concentrations are highest .

And The Role Of Probiotics In All This Is:

” The good bacteria help keep pathogens in small numbers, says Gary Huffnagle . But they also have the effect of stimulating the immune system and improve digestive functions. ”

Infection, disease, immune deficiency , stress sufficient to disrupt the intestinal bacterial flora. Taking antibiotics which is the most virulent attack can also be devastating . The balance of the intestinal flora , however, is a sign of good health. And it is here that probiotics can play a role even if we do not yet know how they operate .

It seems that they are able to promote the development of a strain at the expense of another , via messengers that will synthesize and will modulate the metabolism of a particular bacterial strain . The effect can also result from an interaction between probiotic bacteria and intestinal cells whose metabolism can also be changed . Sometimes a colony of probiotics prevents pathogens proliferate in multiplying and occupying the land on the intestinal wall.

Strains of the best-known probiotics, the most studied and whose effectiveness has been scientifically proven are lactobacilli ( Lactobacillus ) and bifidobacteria ( Bifidobacterium ) or yeast (Saccharomyces )

– Lactobacillus casei , Lactobacillus rhamnosus , Lactobacillus acidophilus and Lactobacillus plantarum for lactobacilli.

– Bifidobacterium longum , Bifidobacterium breve and Bifidobacterium bifidum for bifidobacteria.

– Saccharomyces cerevisiae boulardii for yeasts .

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