gut microbiota Flashcards
microbiota
Microbes- population of microorganisms (bacteria, fungi, viruses, phages) that live or on our body
Microbiota- community of microbes
Metabolome- by products microbes produce
Microbiome- the genes of the microbes that comprise the microbiota
- Is as unique as our fingerprint
- Everyone has a unique microbiota – only ~40% same as someone elses
- 38000 billion bacteria
- As many bacteria as body cells
- 100x more bacteria genes than human genes
- 1000+ bacterial species
gut microbiota in numbers
number of microbial cells (CFU)
stomach- 10^3 CFU/ml
duodenum + jejunum- 10^2-10^5 CFU/ml
ileum + caecum- 10^3-10^9 CFU/ml
colon- 10^12-10^13 CFU/ml
increasing in number of diversity as you go down
role of intestinal microbiota
- Fermentation- of non digestible dietary fibre: producing SCFA + acids provide energy to our gut cells
- Synthesis of some vitamins inclduing vit K and some B vits
- Absorption of nutrients inclduing calcium, magnesium and iron
- Protection and defence- good bacteria compete against bad bacteria for space and nutrients, they produce substances that protect against infection
- Maintainence of the immune system- 70-80% of our immune cells sit in the are in the gut
factors affecting gut microbiota
Diet- food we eat that isnt digested is available to the gut microbiota for fermentation
Age and genetics- as we age, diversity of our microbiota decreases, genetics may affect the microbes that love in our gut + how we interact with those microbes
Medication- antibiotics, PPIs, laxatives, NSAIDs can all negatively impact the composition of our gut bugs
Lifestyle factors- several lifestyle factors that affect the gut microbiota such as sleep,stress and physical activity
probiotic
- Live microorgansims that, when administered in adequate amounts, confer a health benegfit on the host
- Adequate amounts- numbers of the microbe stated are sufficient to provide health benefit
- Health benefit- controlled studies demonstrating health benefit
not probiotics
undefined content of microorganisms
1. Some fermented milks eg kefir
2. Fermented foods
3. LBPs (Live Biotherapeutic Products)
Lack of evidence to support a proposed health benefit
probiotics mechanisms
enhancement of epithelial barrier
increased adhesion to intestinal mucosa
inhibition of pathogen adhesion
compeitive exclusion of pathogsn
production of antimicrobial substances
modulation of immune system
probiotic considerations
- All probiotics work in different ways
- Some MOA might be widspread among common probiotic genera
- Some MOA might be strain specific
- Research is needed to confirm these effects
(mechanisms of action)
probiotic claims- health claims
- No approved health claims for probiotic foods in UK
For probiotic companies - Health benefits or supporting research, cannot be communicated to consumers
- Probiotic is considered an implied health calim and is banned from food products in UK
Why? - Insufficient charactetisation of the microorganism
- Not enough scientific evidence to prove causation
- Little detail on mechanisms
But - Other countries across the globe allow the term
efficacy of probiotics
- Functional gut diseases
- Metabolic disease immunity
- Infectious gut disease
- Liver disease
- Cancer
functional gut disorder- constipation
- Disorder- GI disorder that is common in people of all ages
- Aetiology- pathophysiology of chronic constipation remains poorly understood and is most likely multifactorial
- Action- probiotics may have a role in 1- safe/no adverse, 2. Alternative to using more medication
IBS
- Prevalence- 10% and 20% in the general population
- Aetiology- poorly understood, pathophysiology likely multifactorial, IBS patients have altered gut microbiota
- Action- targeting predominant, low FODMAP diet, potential role of probiotics
IBS and probiotics
probiotic administration may be an effective pharmacolgical therapy in IBS patients
overall results showed probiotics improved IBS symptoms by 53.3%
but high heterogeneity so more evidence for effects is still needed
immune modulators- URTI
upper respiratory tract infection
- About- inflammation of the upper airways often casuing symptomslike a cough, fever, runny nose or blocked nose eg common cold + influenza]
- Causes- viruses
- Action- symptoms relief, antibiotics, probiotics
