lavanya nutankalva,md consultant: infectious diseasesfisftrust.org/upload/ebooks/ppt13.pdf · 2016....
TRANSCRIPT
Lavanya Nutankalva,MD
Consultant: Infectious Diseases
Introduction The word “Probiotic” was derived from the Greek
phrase meaning “for life." was first coined in the 1960s by Lilly and Stillwell.
Probiotics are healthy bacteria that live in the human body and help to maintain the natural balance of organisms (microflora) in the intestines.
The WHO definition: Probiotics as “live microorganisms which when administered in adequate amounts confer a health benefit on the host.”
Food Sources of Probiotics
Yogurt
Fermented soy products
Other fermented foods
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How do Probiotics work?
Modify GI Ecology because of its ability to survive the harsh travel condition of upper GI tract
adhere to the epithelial of the intestine and colonize
compete with the pathogenic microorganisms fornutrient and colonization sites
secrete antibiotic-like substances called bacteriocins,and
provide nutritional services via synthesis of vitamins
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Beneficial effect of ProbioticPossible beneficial effect are –
Either in providing colonization resistance by which the non-pathogen excludes the pathogen from binding sites on the mucosa or
Enhancing the immune response against the pathogen or
In reducing the inflammatory response against the pathogen.
Possible Mechanisms of Benefit
Mechanisms for the benefits of probiotics are incompletely understood. However, three general benefits have been described:
1. Suppression of growth or epithelial binding/invasion by pathogenic bacteria
2. Improvement of intestinal barrier function
3. Modulation of the immune system.
Commonly Used Probiotic Organisms
Two main genera of GP bacteria(Lactobacillus & Bifidobacterium) are used extensively as probiotics.
Other probiotics such as Escherichia , Enterococcus& Saccharomyces are also available in the market.
Probiotic effects are strain-specific which means a beneficial effect produced by one strain cannot be assumed to be provided by another strain, even when it belongs to the same species.
Where do Probiotics come from1. The micro biota of a newborn develops rapidly after the
birth. It is initially dependent mainly on:
the mother’s micro biota,
mode of delivery,
birth environment
and rarely genetic factors.
2. The maternal vaginal and intestinal flora constitutes the source of bacteria, which colonizes the intestine of the newborn.
3. After infancy probiotics are supplied to us by raw foods; lactic acid fermented foods such as yogurt and cheese; and probiotic
supplements.
Theories exist regarding probioticpreparations:
Several theories exist regarding probiotic preparations. These include:
Stimulation of protective cytokines including IL-10 and TGFβ.
Suppression of pro-inflammatory cytokines such as TNF in the mucosa of patients with pouchitis and Crohn'sdisease.
Limit the migration of TH1 cells in inflammed colon tissue in inflammatory bowel disease (IBD).
Common species used Probiotic microorganisms used in food products with
supplementation or fermentation are usually members of the genus Lactobacillus or Bifidobacterium.
Why Probiotics?…
Research Suggests Probiotics Bacteria can
help reduce the risk of certain diarrhea, cancer,allergy, helicobacter pylori, UTIs
assist in managing lactose intolerance, IBD,hepatic encephalopathy, and
enhance the immune functions, overall health
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Health Benefits1. Lactose hydrolysis in lactose-intolerant individuals
+ Lactase activity from probiotic bacteria.
+ Lactase release from lysed bile-sensitive LAB in the small
intestine.
2. Resistance to enteric pathogens
+ Colonization increase resistance to enteric bacteria.
+ Increase systemic immunity.
+ Shortened duration of diarrhea agent production against
pathogens (e.g., lowering pH, bacteriocins and
production of short chain fatty acids.)
3. Anticarcinogenic
- Reducing Colon Cancer
+ Antimutagenic activity with binding to mutagens.
+ Lowering procarcinogenic enzyme activities (e.g.,
nitroreductase, 5-glucuronidase, azoreductase) and
intestinal bacteria in humans and animals.
+ Influence on secondary bile salt concentrations.
4. Reduce toxic compounds from bacterial growth
+ Lower production toxic metabolites in the GIT by
colonic microflora e.g., dimethyamine
5. Immune systema ctivation
+ Strengthen nonspecific and antigen-specific defenses against
infections and tumors
+ Lowering of inflammatory responses
+ Enhance cytokine production
6. Blood lipids, heart disease
Reducing SerumCholesterol Level
+ Alternation of bile salts hydrolyses and reduce blood
cholesterol level
Antihypertensive effects
+ Bacterial peptidase action on milk proteins produces a tripeptide enzyme inhibitor to lower blood pressure in hypertensive animals
7. Inhibiting activity of Helicobacter pylori
+ Production of inhibitors by probiotic bacteria, in
fermented milks, against ulcerative H.pylori
8. Hepatic encephalopathy
+ Inhibition of urease-producing by gut flora
9. Limit urogenital infections
+ Adhesion to urinary and vaginal cells, and exclude
competitive pathogenic bacteria against these bacteria
+ Production of inhibitors (biosurfactants, H2O2)
10. Reducing Intestinal Disorders
Beneficial bacteria, when consumed in large numbers,establish in the intestine and produce antibacterialcompounds which control the pathogens.
11. Modulating Immune Response
Intestinal microorganisms act on intestinal defense barriers and help regulate systemic and local immune response.
12. Reducing Allergic Diseases
Probiotics containing beneficial gut bacteria can have a suppressive effect to such reaction by stimulating theproduction of anti- inflammatory cytokines and reducing allergic reaction in sensitive individuals.
Other aspects The health benefit theory of fermented foods and
beneficial intestinal bacteria is controversial.
Although an association effect, some benefits from their consumption, cannot be denied, many studies have not been able to prove the benefits without doubts.
Factors considered in strain selection
1. Strain Variation: Beneficial strains differ in adherence ability and specificity
2. Sensitivity to Stomach Acids
Survivability of strains to low stomach pH varies greatly.
This effect can be reduced by either reducing stomach
acidity with food or by using strains that are proven
resistant to acid environment
3. Viability and injury of cells
Cells of beneficial bacteria when frozen, dried, exposed to low pH, high salts, and many chemicals can die.
Among the survivors, many can be injured and killed by
stomach acid and bile salts and lysozyme in the intestine.
4. Dose Level and Duration
Consumption of large numbers of live cells (9 log per day), that
are not stressed, over a period of time (ca. 14 d) is advocated to
obtain benefit.
Use of preparations that have low levels of viable cells, many of
which could be stressed, cannot provide expected results.
Many products that are currently marketed do not have the
needed level of viable cells to produce beneficial effects.
Some products also have bacteria that are associated with
improper sanitary practices.
5. True Species and Strains
Many species and strains used by many probiotic food
producers do not have either proper identity or
information of original sources.
Also, many species that were previously regarded as Lb.
acidophilus have been found to be different species, and
many are not of intestinal origin.
Before selecting a strain for a study, one needs to be sure,
thorough testing by recommended methods, that the strain being used is what it is supposed to be.
There is no doubt that some bacterial species and
strains do have beneficial influence on the health of
the GI tract and probably the overall health of humans. But they have to be identified through valid scientific studies.
In recent years, there have been a few reports on the
isolation of lactic acid bacteria, such as Pediococcus
acidilactici and Lb. rhamonosus strains, from
infections in humans.
Lactic acid bacteria, especially those used in food
fermentation and as probiotics, are considered food grade and have been given the GRAS (generally
recognized as safe) status internationally.
In this regard, involvement of these bacteria in health
hazards raised questions about their safety.
The best answer to this doubt is an aphorism of the
16th-century German scientist Paracelsus:
“All substances are poison — the right dose
differentiates a poison and a remedy.”
Thank you