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Microbiome-Based Nutritional Concepts - Coggle Diagram
Microbiome-Based Nutritional Concepts
Distinguish probiotics, prebiotics, synbiotics and postbiotics
Probiotics
: Live microorganisms that when administered in adequate amounts confer a health benefit on the host microbes
Probiotics have been isolated from various sites, such as gut and traditional fermented foods. They mostly belong to genera Lactobacillus and Bifidobacterium, although there are also some members of Bacillus and Escherichia coli for bacteria and the yeast Saccharomyces among others.
Probiotics are not the same:
Bacteria - Kingdom
Actinobacteria - Phylum
Actinobacteria - Class
Bifidobacteriales - Order
Bifidobacteriaceae - Family
Mucosal and stoll microbiome only partially correlates
Human feature a person-specific gut mucosal colonisation resistance to probiotics
Probiotic colonisation is predictable by pre-treatment microbiome and host features
Functional aspect:
Resistance to gastric conditions
Resistance to bile acids (ability to grow in the presence of bile)
Mode of action: anti0microbial activity against pathogens etc.
Challenges in the probiotics field:
Gut microbiome is very personal and stable making it difficult for probiotics to modulate the intrinsic GM
Probiotic colonisation appear to depend on person-specific microbiome and host features
Difficult to document and prove its possible health benefits
Existing probiotics were mainly chosen based on their technological robustness
Prebiotics:
A substrate that is selectively utilised by host microorganisms conferring a health benefit
Act as foods for probiotics and provide health and physiological benefits to the host
Only a few compounds of the carbohydrate group, such as short- and long-chain β-fructans [fructo-oligosaccharides (FOSs) and inulin], lactulose, and galacto-oligosaccharide (GOS), can be classified as prebiotics
Discrete dietary fibre (DF) structures directs SCFA production:
Small difference in DF structure distinctly affect the GM
Discrete DF structures can direct SCFA output toward either butyrate or propionate
Dominant effects
of DF are dose-dependent and plateau at a daily dose of 35g/day
Synbiotics:
Next-generation probiotics made with various
formulations of probiotics and prebiotics
that work in synergism to reestablish the healthy gut ecology
Synbiotics support to reestablish a healthy ecology of microflora within the gastrointestinal tract by strategically combining probiotics with prebiotics, which encourages a more profound effect on gastrointestinal ecology than probiotics or prebiotics alone.
Examples include:
Fructo-oligosaccharides (prebiotic) and Bifidobacteria, Bacteroides fragilis, Peptostreptococcaceae, Klebsiellae (probiotics)
2 types of synbiotics:
Complementary synbiotics:
Mixture of probiotic and prebiotic, each works independently to achieve one or more health benefits.
Synergistic synbiotic:
Mixture of selectively utilised substrate and a live microbe chosen for its ability to deliver a health effect. Components comprising synergistic synbiotics work together to bing about resulting health benefit(s).
Postbiotics:
Soluble products or metabolic by-products secreted by live bacteria or released after bacterial lysis that offer health benefits to the host. They are relatively safer as they lack serious side effects as compared to probiotics.
The concept of postbiotics is built up on the observation that the positive effects of the microflora are facilitated by the secretion of several metabolites. While postbiotics do not comprise live microbes, they show a valuable health outcome through the similar mechanisms that are representative of probiotics while minimizing the risks related to their intake.
Examples:
Galactose-rich polysaccharides, techoic acid (carbohydrate group)
Butyrate, propionate, dimethyl acetyl-derived plasmalogen (lipid group)
Pasteurised A. Muciniphilia to modulate body weight (safe and well tolerated)
IBS: Bifidobacterium bifidum MIMBb75 has shown some effect in RCTs
Discuss the different mode of actions of probiotics and prebiotics
in relation to human health
Modulation of cell-mediated and humeral immune functions
: (Probiotics)
Some probiotics have been shown to
increase phagocytosis
or natural killer cell activity and interact directly with dendritic cells
Some also demonstrate the ability to upregulate antibody secretion translating into improved defences against pathogens and augmenting vaccine responses.
Probiotic strains can increase levels of anti-inflammatory cytokines such as TNF with implications for abating colon cancer and colitis.
Production of organic acids
: (Probiotics)
Probiotic species belonging to the Lactobacillus and Bifidobacterium genera produce lactic and acetic acids as primary end products of carbohydrate metabolism. These organic acids can lower luminal pH and discourage growth of pathogens
Lactobacillus and Bifidobacterium do not produce butyrate but through cross-feeding other commensal microbiota (for example, Faecalibacterium), levels of butyrate and other SCFAs in the gut can increase, potentially influencing many aspects of physiology (including the cardiometabolic phenotyp)
Improvement in barrier function
: (Probiotics)
Several probiotic Lactobacillus and Bifidobacterium strains have been shown to increase expression of tight junction proteins
Another way in which probiotic strains might improve barrier function is through up-regulating expression of mucus-secretion genes, thereby reducing pathogen binding to epithelial cells
Down-regulating inflammation is also regarded as a factor that improves barrier function.
Immune modulation:
(Prebiotics)
There is evidence that prebiotic intervention can reduce type 2 T helper responses and therefore affect allergy.
The most supportive data come from studies in infants. GOS and long-chain FOS in infant formula administered, was associated with a reduction in incidence of atopic dermatitis, wheezing and urticaria to less than 50% of the incidence in non-prebiotic formula-fed infants. I
Improved bowel function:
(Prebiotics)
Improvements in bowel function have often been ascribed to simple faecal bulking by consumption of dietary fibre.
The
humectant (substances that attract water from the air or from deeper in the skin)
water-binding capacity of prebiotic carbohydrates also has the effect of softening stools, making stool passage easier.
Metabolic effects
: (Prebiotics)
The general consensus among studies is that prebiotic intervention has a positive effect on glucose homeostasis, inflammation and blood lipid profile in humans
The hypothesis underlying much research on prebiotics and barrier function and inflammation is that fermentation products such as SCFA probably mediate the beneficial effects through certain mechanisms.
Identified mechanisms of action of prebiotics
:
(a) Prebiotics enter the gut and are selectively utilised. This increases bacterial growth and functionality of specific species.
(b) Faecal bulking and improved bowel habits occur due to microbial growth.
(c) Immune regulation can be influenced by increased biomass and cell wall components of the bacteria. Metabolic products include organic acids, which lower intestinal pH and have resulting effects upon microbial pathogens and mineral absorption.
(d) Metabolic products can also influence epithelial integrity and hormonal regulation. The maintenance of the tight junction integrity can reduce lipopolysaccharide (LPS) translocation, and thus reduce inflammation
Discuss different microbiome-based nutritional concepts to
modulate the gut microbiota composition and activit
y
Engineering of synthetic bacterial therapeutics:
Phenylketonuria (PKU, an inheritable disease which is caused by a defect in the phenylalanine hydroxylase)
This study shows that a genetically engineered strain of EcN 1917, SYNB1618, is able to consume Phe and convert it to non-toxic metabolites in a dose- responsive manner within the human gut
This study shows that a genetically engineered strain of EcN 1917, SYNB1618, is able to consume Phe and convert it to non-toxic metabolites in a dose- responsive manner within the human gut
CRISPR-Based technologies ot provide gut health solutions:
Selective Bacterial Killing
Using bacteriophages and CRISPR/Cas for selectively targeting specific bacterial species
Gut-directed Gene Therapy
Using CRISPR/Cas in engineered live commensal bacteria, which enables them to produce therapeutic molecules in situ