Session 6 - SIBO / DYSBIOSIS

Question 1

What is the microbiota?

Answer 1

The set of microorganisms that share our body space and may be commensal (derives food from another - helpful to humans), symbionts (associated to a large organism), or pathogens (causes disease).

Question 2

Where are these microorganisms found?

Answer 2

Skin, mucosa, gastrointestinal, respiratory, urinary tract, vagina and placenta.

Question 3

What microorganism are vaginally delivered infants enriched in?

Answer 3

Lactobacillus spp (probiotic), which resembles the maternal vaginal microbiota.

Question 4

What are C-section children colonised by instead?

Answer 4

Staphylococcus, streptococcus, or propionibacteria (skin, mouth and gut)

Question 5

At what age is a child’s microbiome like an adults?

Answer 5

3 years of age

Question 6

What influences the gut microbiome across a lifespan?

Answer 6

Diet, medications, stress, exercise, ageing, genetics.

Question 7

How does stress hormones affect gut bacteria?

Answer 7

Stress can change gut bacteria composition through stress hormones, inflammation, and autonomic alterations. Microbial diversity reduces, promoting pathogen expansion.

Question 8

What are some of the functions of the microbiome?

Answer 8

Multiple functions:
- Produces short chain fatty acids (SCFAs) to nourish mucosa and stimulate epithelial cell regeneration.
(SCFAs are fuel for colonic cells)
- Contributes to maturation of immune system ( & GALT- gut associated lymphoid tissue)
- stimulates immune responses to defend pathogens
- synthesis and metabolism of certain nutrients, hormones, vitamins.

Question 9

What nutrients does the microbiome make?

Answer 9

B12, B5, folate and vitamin K

Question 10

What other systems development in the body does the microbiome influence?

Answer 10

immune, metabolic, and nervous system

Question 11

What are the types of SCFAs and how are they produced?

Answer 11

Acetate, propionate, butyrate are produced by bacterial fermentation within large intestine from undigested carbs

Question 12

How does the Gut-Liver axis communicate?

Answer 12

Via the biliary tract, portal vein and systemic meditators.

Question 13

How does the gut influence the liver?

Answer 13

Metabolites from dysbiosis can cause bacterial translocation to the liver, promoting systemic inflammation and bile acid metabolism.

Question 14

How does the liver influence the gut?

Answer 14

Liver metabolites such as acetylaldehyde ethanol metabolites are transported to the intestines affecting microbiota.

Question 15

What pro inflammatory molecule does high levels of bacteria produce in dysbiosis?

Answer 15

Lipopolysaccharide (LPS) - associated with inflammation, diabetes and obesity.

Question 16

How does the GUT brain axis become imbalanced due to stress? (Bi-directional communication)

Answer 16

Stress causes release of cortisol by HPA:
Affecting immune cells;
Altering gut permeability and barrier function;
Changes gut microbiota composition.
(Anxiety, depression, epilepsy, autism).

Question 17

How do we clinically modulate/prevent dysbiosis?

Answer 17

Probiotics & soluble fibre (first for 3months) Prebiotics (insoluble fibres) second.

Question 18

What are some studied probiotics?

Answer 18

Saccharomyces species (boulardii)
Lactobacillus (rhamnosus, etc),
Bifidobacterium (longum etc), &
S.thermophilus (have been found to survive upper GI tract and proliferate colonisation in colon

Question 19

What are the proposed mechanisms of probiotics?

Answer 19

These microbes:

• enhance intestinal immune response.
• Maintain normal levels of SCFA’s, providing energy to intestinal epithelial cells.
• Modulate immune system function (e.g suppress inflammatory cytokines)
• Repair intestinal permeability.
• Suppress growth of pathogenic bacteria
• Upregulate intestinal electrolyte absorption

Question 20

What bacteria is the human colon known to be residence of and what chain of carbohydrates?

Answer 20

Bifidobacteria and are observed to be a preference for oligosaccharides

Question 21

What criteria are used to classify a compound as a probiotic?

Answer 21

• be resistant to acidic pH of stomach, cannot be hydrolyzed or absorbed by GIT
• be fermented by intestinal microbiotia
• the growth or activity of intestinal bacteria can be selectively stimulated.

Question 22

What dietary fibre is bifidogenic (enhances growth of bifidobacteria?) Give examples

Answer 22

Fructo-oligosaccharides and other fructans.

E.g watermelon, grapefruit, ripe bananas, dates, asparagus, leeks, brussel sprouts, onions.

Question 23

What probiotics are affective on allergies?

Answer 23

Lactobacillus rhamnosus strain GG (LGG) given prenatally to mothers can reduce atopic eczema in infants =

Biifidobacterium lactis Bb-12 to infants with atopic eczema

Question 24

T/F - Dietary fibre cannot be digested by human enzymes in the small intestine

Answer 24

True - Dietary fibre (soluble and insoluble) is a diverse group of compounds (including lignin, pectins, resistant starches and other complex carbohydrates) that cannot be digested by enzymes in the small intestines.

Question 25

T/F - Soluble fibres can lower serum LDL cholesterol concentrations and normalise blood glucose & insulin responses

Answer 25

True - examples include psyllium and fibres found in oats

Question 26

What are some examples of soluble, viscous/gel forming, readily fermented fibres?

Answer 26

B-glucans from oats and barley, raw guar gum.

Question 27

What are examples of soluble, viscous/gel forming, nonfermented fibres?

Answer 27

Psyllium

Question 28

Soluble, nonviscous, readily fermented fibers

Answer 28

Inulin (leeks, asparagus, onions, garlic, chicory, oats, soybeans, artichokes)
Oligosaccharides 
Resistant starches (pasta, legumes such as lentils, chickpeas, kidney beans, starchy vegetables).

Question 29

When does the first major exposure of a new-born to microbes occurs?

Answer 29

During the birthing process

Question 30

What gut population does a newborn gain after vaginal delivery?

Answer 30

Lactobacillus (consistent with vaginal bacteria)

Question 31

T/F Bi-directional communication happens in the gut-brain axis only

Answer 31

False - It happens in the gut liver axis too

Question 32

Gut dysbiosis is associated with which of the following human diseases?

Answer 32

Mental health such as anxiety
Metabolic conditions such as diabetes
Liver disorders such as NAFLD

Question 33

T/F: Supplementation with Lactobacillus rhamnosus strain prenatally does not have any effect of prevalence of eczema among infants born to those mothers.

Answer 33

False – Lactobacillus rhamnosus supplements has been shown to reduce the prevalence of eczema in new-borns.

Question 34

T/F Prebiotics are fibre, however not all fibre are prebiotics

Answer 34

True

Question 35

Which fibres are proven to produce more butyrate compared to oligosaccharides?

Answer 35

Resistant starches (FOS)
Butyrate is a four-carbon short-chain fatty acid that is produced through microbial fermentation of dietary fibres (predominantly resistant starches) in the lower intestinal tract.

Question 36

What are the mechanisms of action of prebiotics?

Answer 36

• Food for probiotics
• Allow healthy microbiota to generate short chain fatty acids such as butyrate (generating butyrate)
• down regulate inflammation/disease preventive benefit

Question 37

List 2 diseases associated with gut dysbiosis

Answer 37

NAFLD
Diabetes
IBS/ leaky gut
Anxiety
Eczema