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5) Food Microbiology > 13) Probiotics > Flashcards

13) Probiotics Flashcards

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1
Q

Define probiotics

A

live MOs which when administered in adequate amounts, confer a health benefit to the host

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2
Q

define abiotics

A
  • probiotic strains that have been inactivated by lysis, heat or UV irradiation
  • deomsntrates some effectiveness in downregulating inflammatory response in intestinal epithelial cells
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3
Q

define prebiotics

A
  • non-digestible CHO that acts as food for probiotics
  • helps probiotics to grow and remain in the digestie system
  • not all non-digestible CHOs are prebiotics. They must meet specific criteria
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4
Q

define synbiotics

A

food ingredient or dietary supplements combining probiotics and prebiotics in a form of synergism

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5
Q

what are 4 categories of microbial populations in the gut?

A
  1. autochthonous microbiota
  2. normal microbiota
  3. pathogens
  4. allochthonous microbiota
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6
Q

define autochthonous microbiota

A

populations of microbes present in large numbers and permanently colonizes the host

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7
Q

define normal microbiota

A

MOs frequently in the gut, but can vary in number asnd be sporadically absent

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8
Q

define pathogens

A

MOs that are periodically acquired

can persist and cause infection or disease

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9
Q

define allochthonous microbiota

A

microbes from anoterh origin that are present temporarily

consists of most probiotics

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10
Q

what do probiotic preparations generally contain?

what can they also contain?

A

LAB and bifidobacteria: which are normal constituents of the human GI microflora

may contain other MOs: Saccharomyces boulardii or E.coli Nisell

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11
Q

what are 6 criteria for selection of probiotic strains?

A
  1. origin of strains
  2. biosafety
  3. tolerance to acid and bile salts
  4. adhesion to intestinal cells
  5. production of antimicrobial substances
  6. utilization of prebiotics
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12
Q

should the origin of strains or biochemical activity be considered for selection of probiotic strains?

A

it used to be that strains must be from human origin, but not biochemical activity is considered instead of origin (since LAB exist in diverse environments)

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13
Q

describe how biosafety is used as a criteria for selection of probiotic strains

A

the organism must be generally recognized as safe (GRAS)

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14
Q

describe how tolerance to acid and bile salts is used as a criteria for selection of probiotic strains

what is an exception to this?

A

probiotic strains must be tolerant to acid and bile salts to reach the GIT

exception: when probiotics are sold in enteric coated capsules designed to reach the colon

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15
Q

describe how adhesion to intestinal cells is used as a criteria for selection of probiotic strains

A

Strains should be able to adhere to intestinal cells and colonize the GIT, at least temporarily

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16
Q

describe how production of antimicrobial substances is used as a criteria for selection of probiotic strains

what are examples of antimicrobial substances? what are their roles in the body?

A
  • LAB produces substances inhibitory to other bacteria (lactic acid, H2O2, bacteriocines…)
  • Lactic acid lowers pH of colon which affects ability of pathogenic bacteria to grow in colon and vagina
  • H2O2: discourages urogenital infections
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17
Q

describe how utilization of prebiotics is used as a criteria for selection of probiotic strains

A

probitocis should be able to use fructo-oligosaccharides (FOS)

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18
Q

what are 3 mechanisms of action in which probiotics cultures have beneficial activities on GIT?

A
  1. interaction with the immune system
  2. strengthening the mucosal barrier
  3. exclusion of pathogens
19
Q

describe the interaction of probiotics with the immune system

A
  • shifts the production of cytokines from the inflammation inducing interleukin-12 pathway to the anti-inflammatory IL-10 pathway
20
Q

describe how probiotics strengthen the mucosal barrier

why is this important?

A

they encourage production of protective proteins such as mucins

important b/c dysfunction of the GIT barrier can lead to inflammatory bowel disease

21
Q

describe how probiotics exclude pathogens

A

they inhibit the attachment of bacterial pathogens to the GIT epithelial cells by physically blocking the receptor sites

22
Q

what is the suspected reason due to probiotics for lactose digestion?

A

lactase activity from probiotic cultures

23
Q

what is the suspected reason due to probiotics for weight loss?

A

microbiota with less efficient energy use mechanisms

24
Q

what is the suspected reason due to probiotics for resistance to enteric pathogens?

A
  • colonization resistance

- unfavorable conditions for pathogens (lower pH, bacteriocins, short chain FAs)

25
Q

what is the suspected reason due to probiotics for anti-carcinogenicity

A
  • antimutagenic activity
  • lower pre-carcinogenic enzyme activities (nitroreductase, azoreductase) of colonic bacteria
  • influence on secondary bile salt conc
26
Q

what is the suspected reason due to probiotics for anti-hypertensivity

A

peptidase activity on milk produces a peptide that acts on angiotensi-1, converting enzyme inhibitor to lower blood pressure in hypertensive animals

27
Q

what is the suspected reason due to probiotics for reduction of ulcers

A

LAB producing bacteriocins effective against H. pylori

28
Q

what is the suspected reason due to probiotics for reduction of urogenital infections

A
  • adhesion to urinary and vaginal cells
  • competitive exclusion
  • production of inhibitors (biosurfactants, H2O2)
29
Q

what probiotic formulation was shown to double the lifespan of fruit flies?

what mechanism did this use?

what could this be potentially useful for?

A

L. plantarum
L. fermentum
Bifidobacteria longum
Triphala (prebiotic)

mechanism: gut-brain-axis of communication

could be a tool for neurodegeneration, diabetes, obesity, CVD and other age related chronic diseases

30
Q

what is UC?

A

ulcerative colitis

a chronic inflammatory bowel disease

31
Q

how is E.coli Nissle related to UC?

A

it is thought that E.coli plays a role in flair ups of UC

shown to be almost as effective as mesalazine (which is often used to maintain remission in UC patients)

32
Q

what are 3 proposed mechanisms of E. coli Nissle?

A
  1. direct antimicrobial effect (bacteriocins)
  2. bacterial-epithelial crosstalk
  3. immune- modulatory properties
33
Q

what is the reason that s. thermophilus and L. bulgaricus in yogurt are NOT considered probiotics?

A

they are called “transient” b/c:

  • they are known to proliferate in intestines
  • don’t colonize the GIT
  • may have beneficial activities in the GIT but don’t remain long enough to be considered probiotics
34
Q

what is the reason that s. thermophilus and L. bulgaricus in yogurt ARE considered probiotics?

A

both species have high beta-galactosidase activities

eating yogurt improves lactose digestion and eliminates symptoms of lactose intolerance

35
Q

what has been shown to occur when L. rhamnosus is consumed?

A

colonizes the vagina following oral intake

36
Q

what did Gregor Reid study?

A

how oral probiotics can improve vaginal health and prevent urinary tract infections

37
Q

why are probiotics often used in animal nutrition?

A
  • enhancement of animal growth
  • wt gain
  • reduction in carriage of human enteric pathogens
38
Q

why is reducing pathogens at the farm level important?

A

it results in a reduction of risk of foodborne illness

39
Q

what are limitations of probiotics studies?

A
  1. the effects of probiotics is smaller than conventional drugs and is likely confounded by age, diet, lifestyle
  2. study results vary w/ many factors (such as strains used, population level of the probiotic cells, health market targeted, etc…)
  3. there is no agreement on biomarkers for a healthy GIT
40
Q

what did the study by Suez et al (2018) study?

A

examined the effects of probiotics administered after antibiotic consumption of the GIT community, in mice and humans

41
Q

what did the study by Suez et al show?

A
  • probiotics better colonizes after antibiotic treatment in humans and mice b/c probiotics delays (1) return of the indigenous microbiome (2) return to a homeostatic mucosal transcriptome
  • taking antibiotics eliminates colonization resistance to probiotics from resident microbiota, which causes you to become colonized w/ more probiotic organisms than if you didn’t have probiotics
42
Q

what did the study by Suez et al (2018) NOT show?

A

it didn’t examine:

  1. if probiotics are effective in reliving post-antibiotic clinical symptoms
  2. if there are clinical consequences to prolonged probiotic dysbiosis
  3. other antibiotics/probiotics and other factors
43
Q

what are regulations of probiotics in europe?

A

they are not governed under specific regulatory frameworks

but now there is a new regulation where heatlh claims ofr foods must have relevant scientific justification

44
Q

what are regulations of probiotics in canada?

A
  • probiotic organisms can be added to food pdts is they are on a list of safe organisms
  • there is a list of approved marketing statements
  • probiotic foods are classified as food, but must be classified as a natural health product (NHP) with evidence to Health Canada if want to sell it as a pdt with “health” benefits

5) Food Microbiology (21 decks)

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