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Functional foods and health > Functional Food Lecture 8 & 9 > Flashcards

Functional Food Lecture 8 & 9 Flashcards

1
Q

What is the Gut?

A

-central organ that maintains our health
-complex system consisting of microbial and host cells in ratios close to 1:1

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2
Q

What is the microbiome

A

Gut microbiota refers to a collection of microorgs that are present in the GIT.
Gut microbiome refers to the collective genomes of all the microorgs present in the gut

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3
Q

Bacteria in the gut

A

10^13-10^14 heterogenous bacteria in the gut

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4
Q

Metabolic niches in the gut microbiome

A
  • The localization and spatial organization of the gut microbiota are not uniform along the GI tract
  • This dynamic gut ecosystem consists of many unique features, such as microniches, pH gradients, and dynamic microbe-tisse interactions of relevance for microbial biotransformations.
  • The highest density of bacteria is present in the large intestine with recent estimates in the large intestine of 10^13 bacterial cells
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5
Q

Functions of the gut microbiome -Metabolism

A
  • Metabolism= contains more genes than host so is involves with metabolic functions that the host cannot do - ‘Metabolic Organ’- Vits AAs and metabolise non-digestible CHO.
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6
Q

Functions of the gut microbiome - Host protections an immune system development

A
  • Antimicrobial compounds (bacteriocins)
  • Pathogen displacement (competitive exclusion effect)
  • Signal to innate immune system to release protective peptides, cytokines, WBCs
  • Allergy prevention
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7
Q

Functions of the gut microbiome - Gut-brain axis

A

Communication system that integrates neural, hormonal and immunological signalling between the gut and the brain.
-Bidirectional: enables the brain to command GIT functions

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8
Q

Role of gut microbiota : Supporting evidence

A
  • Germ-free animals: more susceptible to diseases
  • Antibiotic-treated animals (inc humans) more susceptible to disease
  • Dosing of animals with faecal suspensions has been shown to prevent infection.
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9
Q

Dysbiosis

A

The imbalance between the commensal and pathogenic microbiota, in which the commensal microbes can enhance the immune system and the pathogenic microbes cause immunity dysfunction and inflammation of the gut

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10
Q

Development of the Gut microbiome - During delivery

A
  • Greatly developed during birth and the first year of life
  • faecal & vaginal microorgs from the mother induce the start of the gut microbiome
  • takes 3 years for the gut microbiome to build up, diversify and stabilize.
  • Stable until old age
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11
Q

Amniotic fluid samples have detected

A

bacterial DNA in the meconium suggesting the microbiome may commence in utero

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12
Q

Development of the git microbiome - After delivery

A
  • Neonates gut microbiomes are quickly colonized after deliver
  • influenced by mode of delivery and gestational age and diet of the infant.
  • diff between natural and c section births
  • Gestational age of infant
  • Diet of infant (breastfed/formula)
  • Antibiotic use
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13
Q

Development of the gut microbiome - 1st years of life

A
  • changes dramatically in 1st few years and then remains stable
  • at approx 3 years old childs phylogenetic composition and diversity of intestinal microbiota is evolved towards those of adults
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14
Q

Development of the gut microbiome - 1st years of life - External and internal host related factors

A

External= microbial load of immediate environment, type of food eaten, feeding habits, lifestyle, use or abuse of antibiotics, age, disease
Internal= intestinal pH, microbial interactions, external temp, genetics
However given all factors the gut is fairly stable at the phylum stage

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15
Q

In adults stable and diverse gut microbiome dominated by

A

Phyla
- firmicutes
- bacteriodetes

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16
Q

Firmicutes

A

gram positive
rod shaped
spherical bacteria
EX: lactobacillus, Bacillus

17
Q

Bacteriodetes

A

Gram negative and often exhibit a distinctive rod shaped morphology.
EX: Bacteriodes, prevotella

18
Q

Microbiome analysis : Isolation of gut microbiome : Consider source

A

Feces. Biopsy, luminal brush, laser capture microdissection, catheter aspiration, intelligent capsule, surgery, in vivo model, FISH (Fluroescent In Situ Hybridization)

19
Q

Microbiome Analysis: Feces

A

Adv= convenient and repeatable sampling
Non- invasive
Suff biomass for analysis
inexpensive
Disadv= cant accurately reveal changes in the gut microbiota
Uneven distribution of bacteria within feces

20
Q

Microbiome Analysis: Biopsy

A

Adv= Accurate description of microbiota assoc w/ tissue
controllable sampling site
Disadv= Bowel prep effects
invasive
inevitable contamination
insuff biomass yield
expensive
not suitable for a healthy control.

21
Q

Microbiome Analysis: Luminal brush

A

Adv= Accurate description of microbiota assoc with tissue
controllable sampling site
Disadv= Bowel prep effects
invasive
inevitable contamination
Expensive

22
Q

Microbiome Analysis: Laser capture microdissection

A

Adv= accurately reflects host-microbe interactions
Controllable sampling site
Disadv= Bowel prep effects
invasive
inevitable contamination
insufficient biomass yield
expensive

23
Q

Microbiome Analysis: Catheter aspiration

A

Adv= accurate description of microbiota assoc with tissue
Controllable sampling site
Disadv= Bowel prep effects
invasive
inevitable contamination
patient discomfort

24
Q

Microbiome Analysis: Intelligent capsule

A

Adv= Accurate description of luminal microbiota
non invasive
no bowel prep
no contamination
Disadv= Expensive
technically difficult

25
Q

Microbiome Analysis: Surgery

A

Adv= accurate description of microbiota in sampling site
controllable sampling site
no contamination
Disadv= pre-op prep effects
not suitable for health control

26
Q

Microbiome Analysis: In vivo model

A

Adv= convenient &repeatable sampling
non invasive
Suff biomass for analysis
No contamination
inexpensive
Disadv= abnormal intestinal anatomy
not suitable for health control

27
Q

Microbiome Analysis: FISH

A

Adv= accurately reflect spatial org or microbiota and host microbiota interactions
Disadv= probe needs to be designed in advance
not suitable for complex microbiome

28
Q

Microbiome Analysis: Genomic approaches

A

16SrRNA gene sequencing identifies what microbes are in the gut.

29
Q

Microbiome Analysis: Genomic approaches: Shotgun metagenomics sequencing

A

Involves
the sequencing of DNA extracted directly from a
microbial community without prior amplification of specific
marker genes. This technique provides a comprehensive view
of the entire microbial community, including bacteria, archaea,
viruses, and eukaryotes, and allows for the analysis of
functional potential, gene content, and metabolic pathways

30
Q

Factors affecting the composition and function of the large
intestine metabolic niche

A

EXTRINSIC= mode of delivery, type of feeding, hygiene parameters, antibiotic use, environment, age, food habits, lifestyle, stress, disease(IBS)
INTRINSIC= genetics, temp, gastric acid secretion, oxygen, bile acids, epithelial turnover, anitcommensal slgA, mucin , antimicrobial peptide production, GI motility

31
Q

Intrinsic: Genetics

A

Early life: genetics influence gut microbiota but by time 1 year
old the microbiota has diversified
Triplets: 2 identical and 1 non-identical
2 identical have same microbiota and other has different microbiota but by time 1 year old all have very different microbiota

32
Q

Extrinsic: Diet and Lifestyle

A

Elderly: Gut microbiota composition correlates with diet and health in the elderly.
Microbial diversity decreases as one ages due to: pH, Oxygen, Bile acids, Epithelial turnover, mucin, surgery, antibiotics, stress, chronic diseases

33
Q

Some indigenous microorganisms could acquire pathogenic
roles in a genetically predisposed host due to environmental or
dietary factors are called?

A

pathobionts and cause or promote onset of intestinal inflammation

34
Q

Gut microbiome and disease

A

IBD, behavioural disorders (Brain-gut axis), colorectal cancers, allergies, metabolic diseases- T2 diabetes, obesity

35
Q

Enhancing gut microbiota

A

Probiotics: replenish good bacteria
Prebiotics: non-digestible food source for beneficial gut microbiota
Dietary Fibre: promotes growth of beneficial gut microbiota

Functional foods and health (9 decks)

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