Microbiome (5) Flashcards
Where can we find microorganisms that form complex + distinct ecosystems ?
our skin, mucosa, gastrointestinal, respiratory, urinary tract, the vagina, placenta
What influences the microbiome?
the birthing process, diet, medications, stress, ageing, genetics,lifestyle choices
In vaginal births what microbe is the infant initially enriched in?
Lactobacillus spp
Name 3 functions of the microbiome functions?
- Establishes at the intestinal barrier and stimulates intestinal epithelial cell regeneration and nourishes mucosa by producing SCFA’s
- contributes to the development and function of the immine, metabolic and nervous system
- assists the synthesis and metabolism of nutrients, hormones and vitamines in intestine
What are SCFA;s and how are they produced
SCFAs are the major source of energy for colonic cells. They are produced by bacterial fermentation within the large intestine from undigested carbohydrates and exhibit multiple functions
What are the 3 main SCFA’s
acetate
propionate
butyrate
What are (3) functions of SCFA's (Pick 3)
- activation of mucin release
- increase of mucosal blood supply
- generation of acidic mileu
- stimulation of electrolyte and H2O absorption
- key energy source for colon cells
- anti-inflammatory effects
- protection of epithelial barrier
- regulation of cell prolifeartion, differentiation and apoptosis
What is the communication link between the gut liver axis
throught eh bilary tract, portal vein, and system mediators
What is ‘SIBO’
Small intestine bacterial overgrowth
What is SIBO defined as
the presence of excessive bacteria in the small intestine and is implicated as the cause of chronic diarrhoea and malabsorption
What are symptoms of SIBO
bloating, abdominal distension, abdominal pain or discomfort, diarrhoea, fatigue, weakness
What are clinical manifestations of SIBO
steatorrhea, weight loss, vitamin and mineral deficiencies (B12, folate, fat soluble vitamins, iron)
What inflammatory conditions are linked to Dybiosis
colon cancer, ulcerative colitis, crohns disease, IBD
What have high levels of LPS (lipopolysaccharide) been associated with ?
Inflammation and reported in T2 diabtetes, obese and insulin-resistant mice
How does the gut microbiota modulte the gut-brain axis
via endocrine immune, and neural pathways
How is the gut microbiota composition changed?
- Under conditions of stress, HPA-axis regulates cortisol secretion, and cortisol can affect immune cells, alter gut permeability and barrier function, and change gut microbiota composition.
How is dybiosis and the liver related?
dysbiosis may cause increased intestinal permeability and bacterial translocation on reaching teh liver, impairing the bile acid metabolism and promotes a systemic inflammation and liver damage
Whats the definition of probiotics?
Live microorganisms which when administered in adequate amounts, confer a health benefit on the host
What are the most recognised probiotics and why? (3)
Bifidobacteria, lactobacilli and S. thermophilus are the most recognised because of their ability to survive the Upper GIT and proliferate the colonisation in the colon
What are health benefits that Bifidobacteria, lactobacilli and S. thermophilus ? (4)
o prevention and treatment of diarrhoea (particularly rotaviral and antibiotic associated),
o lactose digestion,
o enhanced gut immune function,
o prevention and treatment of food allergy and its systemic effects (atopic dermatitis and possibly GI allergic disease)
What are the main metabolite produced from probitoics and what do they do
short chain fatty acids-SCFA (butyrate, propionate, and acetate) that act as a major energy source for intestinal epithelial cells and therefore strengthen the mucosal barrier.
What are 3 proposed mechanisms of probiotics?
- block the adhesion of pathogenic bacteria to the intestinal epithelium; producing inhibitory agents
- ehance the intestinal immune response
- repair intestinal permeability
What are PREbiotics defined as?
a selectively fermented ingredient that results in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health
What is the main PREbiotic in human colon
Bifiodbacteria and they are observed to have a preference for oligosaccharides
What 3 criteria are used to classify a compound as a prebiotic?
a. resistant to acidic pH of stomach, cannot be hydrolyzed by mammalian enzymes, not absorbed in GIT
b. can be fermented by intestinal microbiota
c. growth/activity is selectively stimulated by this compound and this process improves hosts health
What is the saying “All prebiotics are fibre…..”
All prebiotics are fibre, but not all fibre are prebiotics
What are some examples of prebiotic fibre?
- polysaccharide - dietary fibre + resistant starch
- oligosaccharides (carbohydrates of 3-9 saccharide units)
- naturally occuring, garlic, onion, leeks, wheat and oats
What are the benefits of fermatable fibres?
- act as prebiotics
- SCFA generation
- increased water/sodiu, absorption in the colon
- provision of energy
What is the MOA for dietary fibre and prebitoics
fermentation in the colon and changes in gut microflora
What (3) things provide a barrier that prevents pathogenic bacteria from invading the GIT
gut immune system, colon and mucosal microflora
What are the 4 effects of prebiotics-probiotics synergy in prevention of disease
- dietary intake
- altered gut bacteria
- biologic effects - metabolism, immune system production of pro and pre inflammatory metabolites
- host disease - CVD, obesity, autoimmune disease
Name 3 well established probiotic effects
- Normalisation of passing stool and stool consistency
- Prevention of respiratory tract infections (common cold, influenza) and other infectious diseases as well as treatment of urogenital infections
- Prevention and alleviation of unspecific and irregular complaints of the GIT in healthy subjects.
What are the effects of probitoics on allergy?
Lactobacillus rhamnosus strain GG (LGG) given prenately to mothers with high risk of atopic disease had reduced prevelence of atopic eczema
Why formula supplemented with LGG or Bifidobacterium lactis Bb-12 is more effective than unsupplemented formula in eczema alleviation of infants
