Download GUT FLORA AND HEALTH

WORLD DIGESTIVE HEALTH DAY


29th May.
Bangladesh Gastroenterology Society
creating awareness nation-wide.
Slogan
Gut microbesImportance in health and disease
Dr. Jimma Hossain
MBBS, MD (Gastro)
Assistant Professor
Department of Gastroenterology
Rangpur Medical College & Hospital
Gut flora



Gut flora consists of
microorganism species.
a
complex
of
Human intestine carries about 100 trillion
microorganisms.
Ten times greater than total cell in body.
Gut flora

About 500 different species live in gut.

Bacteria makeup the majority.

Over 99% of bacteria are anaerobes.

Fungi, protozoa and archaea also part of gut
flora,but little is known about their activities.
Gut flora

Most bacteria belong to genera
Bacteroids,Clostridium,Fusobacterium,Eubacterium,Ruminococcus,
Peptococcus,Peptostreptococcus and Bifidobacterium.



Bacteroids alone constitute 30%.
Fungi include Candida, Saccharomyces,
Aspergillus and Penicillium.
Archea another large class of flora important
for metabolism of bacterial products of
fermentation.
Gut flora and diet

Association between concentration of
microbial community and dietary
components.

Prevotella with carbohydrate based diet.

Bacteroids with animal protein diet.

Gut flora can be changed by following a long
term diet.
Acquisition of gut flora




At birth digestive tract is sterile.
Colonised by microbes within first few days.
All infants initially colonized by E.coli and
Streptococci and subsequently anaerobes
predominate.
Breast fed babies predominated by
Bifidobacteria.

With introducton of other foods,a diverse
microbial population develops.
Gut flora and health


Research suggests relationship between gut
flora and humans not merely commensal ,but
rather mutualistic.
Though people can survive without gut
flora,microorganisms perform a host of useful
functions.
Gut Flora
A healthy digestive system should contain at least 8085% friendly bacteria to prevent diseases caused by
organisms like E. coli & salmonella.
Duodenum
10¹-10³ cfu/ml
Stomach
10¹-10³ cfu/ml
Jejunum/Ileum
Colon
10¹¹-10¹² cfu/ml
104-107 cfu/ml
Useful Functions





Recycle energy by fermenting unused energy
substrate.
Early development & training of the immune
system.
Prevention of the growth of harmful pathogenic
bacteria.
Regulation of the development of gut.
Production of vitamins such as biotin, folate and
vitamin K.
Useful Functions


Antidiabetic,anticarcinogenic,hypocholesterole
mic role.
However,in certain conditions,some species
capable of causing disease by producing
infection,increasing cancer risk for the host.
Fermentation

Saccharolytic - more favorable.

Proteolytic- less favorable.
Saccharolytic fermentation




Carbohydrates fermented into short chain
fatty acids(SCFAs).
Acetic acid,propionic acid and butyric acid.
These are used by enterocytes and other cells
and helps mineral absorption.
Butyric acid provides energy to gut cells and
prevents cancer.
Potential Mechanisms of Anti-neoplastic Action
Angiogenesis
Apoptosis
Proliferation
Butyrate
Inflammation
Immunosurveillance
Proteolytic Fermentation


Breaks down proteins like enzymes,dead host
and bacterial cells,collagen,elastin.
Can produce toxins and carcinogens in
addition to SCFAs.
Trophic effects




SCFAs increase growth of intestinal epithelial
cells and control proliferation and
differentiation.
Growth of the lymphoid tissue near the gut.
Prevents cells from injury.
Prevents cancer.
Suppression of pathogenic microbial growth






Prevents harmful bacteria through competitive
exclusion.
By competing for nutrition and attachment sites to
epithelium.
Produce bacteriocins that kills harmful microbes.
By producing acids during fermentation lowers
colonic PH and thus prevents proliferation of harmful
species and facilitating helpful species.
By influencing mucosal barrier.
By influencing immune function.
Immunity



Gut flora have regulatory effects on mucosal
immune response.
Key in promoting early development of gut’s
mucosal immune system.
Stimulate lymphoid tissue associated with the
gut to produce antibodies to pathogens.
Immunity
Modulation of immune response by flora
Stimulation of mucosal immunity
Suppression of mucosal immunity
* Better oral vaccine responses
* Control infections
* Reduce allergy
* Reduce inflammation
Prevention of allergy



Can influence tolerance of gut immune
system to antigens
Helpful gut flora stimulate immune system
and train it to respond properly to antigens.
Lack of these bacteria in early life leads to an
inadequately trained immune system that
over reacts to antigens.
Prevention of allergy


Composition of gut flora varies in patients
with/without allergies.
In allergy:
Bacteroides, Bifidobacteria
S.aureus, C.difficile
Prevention of inflammatory bowel disease






SCFAs prevent IBD.
Some form of bacteria can prevent
inflammation.
Linked to good hygiene in youth.
Inversely linked with poor sanitation during
first year of life.
Antibiotics that kill native bacteria.
High concentration probiotics decrease
inflammation.
Alteration in flora balance


Inflammation
Antibiotic use

AAD






Irritating bowel directly
Changing levels of gut flora, alteration in flora balance.
Allowing pathogenic bacteria to grow
Decreased ability to ferment CHO and bile acids
Over growth of C.difficile
Gut flora composition also changes in severe illness,
ischaemia, immune compromise.
Alteration in flora balance



Pharmabiotics
 Generic term to encompass any form of
therapeutic exploitation of commensal flora
 Use of live probiotic bacteria,prebiotics,synbiotics(genetically modified
commensal).
 Pre-biotics : dietary components that foster
the growth of micro organisms in the gut
Pregnancy.
Wt loss.
Role in disease


Have pathogenic properties in addition to
their health-inducing ones.
They can produce toxins and carcinogens.
Role in disease


Implicated in conditions as MOF,sepsis,colon
cancer and IBD.
A major factor in health is the balance of
bacterial numbers ; if too high or low,will
harm the host.
Role in disease


Some genera-Bacteroids and Clostridium
associated with in increase in tumor growth
rate.
Lactobacillus and Bifidobacteria are known to
prevent tumor formation.
Role in disease


Bacterial translocation in certain conditions
causes sepsis.
Implicated in colitis, obesity.
Conclusion



The gastrointestinal tract is now considered one of
the most complex microbial ecosystem on earth.
Till to date, little is known about this ecosystem.
Researches are going on to explore undiscovered
aspects of gut flora in health & disease.