Learning goals case 10
1. What is the gut microbiome?
The human gut microbiota consists of trillions of microbial cells and thousands of bacterial
species. The specific compositional features differ among individuals, and although the
mature microbiota is fairly resilient (redelijk veerkrachtig), it can be altered within individuals
by both internal and external stimuli.
- External factors, such as diet
Transient diet-induced alterations occur independently of body weight and adiposity and
are detectable in humans within 24 to 48 hours after dietary manipulation. Changes to
host dietary patterns alter bacterial metabolism and favor species most suited to use
consumed fuel sources. Diet induced-changes have important effect on the physiology
and disease processes.
2. How is the gut microbiome influenced by the food you eat?
CARBOHYDRATES
Complex CHO exhibit a diverse array of monosaccharide linkages, many of which are
indigestible by humans. Gut microbes, on the other hand, possess several hundredfold more
CHO-degrading enzymes and thus use indigestible CHO as their primary energy source.
Indigestible CHO are named fibers. But there are fibers which can be and cannot be digested
by the gut bacteria. The term “microbiota-accessible carbohydrate,” or MAC describes CHO
that are metabolically available to gut microbes.
Societies that consume high levels of MAC have a greater microbial richness and diversity
as compared to industrialized societies.
Consequences of MAC reduction
- Some bacterial species that normally consume dietary glycoproteins can also use
glycoproteins of the intestinal mucus layer as an alternative energy source. Therefore,
when this happens chronically the integrity of the barrier will be reduced and also
inflammation and pathogen susceptibility is enhanced (proven in animal studies)
- Reduction in short chain fatty acid (SCFA) production. SCGFA are the primary end
products of bacterial fermentation, this is also why the bacteria and human live in
symbioses. SCFAs signal via the central nervous system and several G protein–coupled
receptors (GPCRs) to modulate a range of physiological processes…
Energy homeostasis
Lipid and carbohydrate metabolism
Suppression of inflammatory signals
Two SCFAs, butyrate (mostly) and propionate, also act as histone deacetylase
(HDAC) inhibitors, suggesting that they can epigenetically influence host gene
expression
, Consumption of diets containing amounts of fiber above recommendations is associated with
a reduced risk of coronary heart disease and type 2 diabetes.
- SCFAs (butyrate, propionate and acetate) are the main metabolic products of fibers by
gut microbes. The SCFAs are ligands of …
the free fatty acid receptors FFAR2 and FFAR3 in the colonocytes.
Immune and enteroendocrine cells (EECs)
Enteric neurons where they serve to trigger different biological actions
1. What is the gut microbiome?
The human gut microbiota consists of trillions of microbial cells and thousands of bacterial
species. The specific compositional features differ among individuals, and although the
mature microbiota is fairly resilient (redelijk veerkrachtig), it can be altered within individuals
by both internal and external stimuli.
- External factors, such as diet
Transient diet-induced alterations occur independently of body weight and adiposity and
are detectable in humans within 24 to 48 hours after dietary manipulation. Changes to
host dietary patterns alter bacterial metabolism and favor species most suited to use
consumed fuel sources. Diet induced-changes have important effect on the physiology
and disease processes.
2. How is the gut microbiome influenced by the food you eat?
CARBOHYDRATES
Complex CHO exhibit a diverse array of monosaccharide linkages, many of which are
indigestible by humans. Gut microbes, on the other hand, possess several hundredfold more
CHO-degrading enzymes and thus use indigestible CHO as their primary energy source.
Indigestible CHO are named fibers. But there are fibers which can be and cannot be digested
by the gut bacteria. The term “microbiota-accessible carbohydrate,” or MAC describes CHO
that are metabolically available to gut microbes.
Societies that consume high levels of MAC have a greater microbial richness and diversity
as compared to industrialized societies.
Consequences of MAC reduction
- Some bacterial species that normally consume dietary glycoproteins can also use
glycoproteins of the intestinal mucus layer as an alternative energy source. Therefore,
when this happens chronically the integrity of the barrier will be reduced and also
inflammation and pathogen susceptibility is enhanced (proven in animal studies)
- Reduction in short chain fatty acid (SCFA) production. SCGFA are the primary end
products of bacterial fermentation, this is also why the bacteria and human live in
symbioses. SCFAs signal via the central nervous system and several G protein–coupled
receptors (GPCRs) to modulate a range of physiological processes…
Energy homeostasis
Lipid and carbohydrate metabolism
Suppression of inflammatory signals
Two SCFAs, butyrate (mostly) and propionate, also act as histone deacetylase
(HDAC) inhibitors, suggesting that they can epigenetically influence host gene
expression
, Consumption of diets containing amounts of fiber above recommendations is associated with
a reduced risk of coronary heart disease and type 2 diabetes.
- SCFAs (butyrate, propionate and acetate) are the main metabolic products of fibers by
gut microbes. The SCFAs are ligands of …
the free fatty acid receptors FFAR2 and FFAR3 in the colonocytes.
Immune and enteroendocrine cells (EECs)
Enteric neurons where they serve to trigger different biological actions
