PROBIOTICS: OUR LITTLE FRIENDS
Introduction
When ingested in a proper count, probiotics are the
microorganisms that impart health benefits to the host [1]. Most commonly used
strains are Bifidobacterium and Lactobacillus, which are the
predominant group of the gut microflora [2]. The Probiotics have been around
for more than a decade now and due to numerous researches done on them, the
probiotics have gained a recognition because of their multiple health benefits.
The general population as well the food market has become very interested in
this type of microorganisms.
Often claims have been made by the food industries
that their probiotic product is the best, but the selection of the microbes is
a tedious job and depends upon the gastrointestinal mucosa, gastric acid, bile
ability to stick to the intestinal lining and the competitive expulsion of the
bacteria [3]. The mechanism behind the benefits provided by the probiotics are unknow
but are most likely to be multi factorial.
Probiotics have been shown to supress Diarrhea [4], combat
or minimize lactose intolerance [5], anti colorectal cancer [6], reduce bowel
irritability [7], and the secretion of anti microbial substances and
strengthening the gut epithelial and adherence to the mucosa and epithelium
[8], etc.
The benefits provided by these probiotic products
tends to be strain specific, that is why a maximum number of these strains
should be consumed [9]. The selection and careful manufacturing of these
strains and careful manufacturing of probiotics products allow these health
benefits. The objective of this reading is to explore the various mechanisms
of the action of the probiotics.
CONTENT: MODE OF ACTION
Epithelial Barrier Modification

Several studies have indicated that enhancing the
expression of a gene involved in tight junction signaling, it is a possible
mechanism to reinforce or to maintain the integrity of the gut [10]. Moreover,
incubating the gut with Lactobacilli increases the secretion of various
gene coding adherence junction proteins [11]. Recent data have suggested that
probiotics may repair the barrier function after the damage has been done. Mucosal
production may be increased by in vivo of probiotics, but further studies are
required.
Competitive Expulsion of the Pathogenic
Microorganisms
The term Competitive expulsion was first used in 1969
by Greenberg, to refer to a scenario where one species competes with another
vigorously for survival inside the gut of the host [12]. This can take place via a lot of mechanisms Hostile microecology, Production and secretion of anti
microbial substances, Selective metabolites and depletion of essential
nutrients [13].
Probiotics act by antagonistic activity by preventing
the interaction of surface protein and the mucins [14]. This happens via the
various mechanisms of the probiotic and one such mechanism used by the
probiotics is the modification of the environment making it less suitable for the
competitor. Some LABs and Bifidobacterium share the carbohydrates
binding sites with the Enteropathogens this makes them compete [15]. This entire
mechanism is based on steric hindrance and this is how the pathogen is
eliminated
Production of Antimicrobial Substance
One of the proposed theories as to how the probiotics
work is the production of LMW compounds mainly the organic acids and the
production of antimicrobial substances, bacteriocins.
Acetic acid, Lactic acid have a strong inhibitory
action against the gram-negative bacteria and have been proven to be the most
effective compound contributing to the suppressed activity of the pathogens [16].
They work by lowering the pH making the environment unfit for the survival and,
they enter the cytoplasm and kill the pathogen from inside. Many LABs also
produce bacteriocins which kill the pathogen by disintegrating the cell wall of
the pathogen by pore formation [17].
Probiotics and its effects on Immune Response
It is well established that Probiotics can exert
immunomodulatory effect, the probiotics have the unique ability to interact
with the Epithelial and the Dendric Cells (DC).
{Dendric cells are the antigens presenting cells,
their main function is to process antigen and provide it to T cells of the immune
system}
The immune system consists of two mechanisms innate
and adaptive. The adaptive immune system works by T and B lymphocytes and hence
they are specific to the type of antigen. Taking in consideration the innate
immune system, it responds to Pathogen associated molecular Pattern (PAPM),
shared by a vast majority of pathogens [18]. The primary response is triggered
by (PPR) Protein Recognition Receptors they in turn bind PAMP. The immune
response is however, much more complex and has various steps and throughout
these steps signals are forwarded when interaction with bacteria takes place
[19]. The probiotics interact with the DC which boosts immunity (innate and
adaptive). Probiotics also interact with the IECs (intestinal epithelial
cells). Both IECs and DC interact with the gut flora/ probiotics via the PPR
which in turn boost the immunity [19].
My Personal views to this would be that Probiotics
sure are a superfood of the future and has tremendous health benefits, but
most of the proven health benefits mechanisms of Probiotics are in Vitro. Thus,
more in-depth studies are required.
Conclusion
This reading

gives the mechanism of action of probiotics but the quest for a better understanding of probiotics continues. This data that we had is a reservoir of information, a reservoir big like an ocean, an ocean with endless possibilities. The future findings and researches hold the key for the importance probiotics and its role in food industry.
References
Miriam B, Diaz J, Quezada S, et all: probiotic mechanism of action, 2012
1- WHO:
health and nutritional properties of the probiotics in foods including powder
milk with live acid bacteria. 2001 www.foa.org
2- Guarner
F, Malagelada Jr: Gut flora in health and disease, 2003.
3- Collins
JK, Thomton G, Sullivan Go: selection of probiotic strains foe human
application, dairy, 1998
4- Lye
HS, Kuan CY, Ewe JA, et all: improvement of hypertension by probiotics,2009
5- Pelletierx,
Laure-Boussuge S, Donazzolo: Hydrogen excretion upon the consumption of dairy
products in lactose intolerant male subjects; importance of live microbes,2001
6- Rafter
J, Bennette H, Caderni G, et all: Dietary symbiotics reduces the risk of cancer
in colon cancer patients,2007
7- Hoayyedi
P, Ford AC, Talley NJ, et all: efficiency of the probiotic to cure the
irritable bowel syndrome,2010
8- Collad
MC, et all:bio active foods in promoting health, Chennai, academic press,2010
9- Williams
NT: Probiotics AMJ :Health pharma system,2010
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