Lavanya Nutankalva,MD Consultant: Infectious Diseases

Transcription

1 Lavanya Nutankalva,MD Consultant: Infectious Diseases

2 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.

3 3 Food Sources of Probiotics Yogurt Fermented soy products Other fermented foods

4 4 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 for nutrient and colonization sites secrete antibiotic-like substances called bacteriocins, and provide nutritional services via synthesis of vitamins

5 Beneficial effect of Probiotic Possible 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.

6 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.

7 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.

8 Where do Probiotics come from 1. 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.

9 Theories exist regarding probiotic preparations: 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's disease. Limit the migration of TH1 cells in inflammed colon tissue in inflammatory bowel disease (IBD).

10 Common species used Probiotic microorganisms used in food products with supplementation or fermentation are usually members of the genus Lactobacillus or Bifidobacterium.

11 11 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

12 Health Benefits 1. 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.)

13 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

14 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

15 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)

16 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.

17 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.

18 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

19 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.

20 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.

21 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.

22 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.

23 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.

24 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.

25 Thank you