Metabolism - Gut Flora and Obesity:

Question 1

Gut Flora & Obesity

Answer 1

• Overweight individuals have different gut microflora compositions to lean individuals (e.g. reduced Bifidobacterium).
• There is evidence that a higher ratio of Firmicutes v. Bacteroidetes phyla may be implicated in obesity.
• Scientists have shown that transferring the gut flora from obese mice to lean mice causes the lean mice to gain weight and vice versa.
• What we eat affects which species of bacteria proliferate in the gut.
• A high-fat diet causes increased levels of gram-negative bacteria and reduced levels of bifidobacteria.

Question 2

Short Chain Fatty Acids

Answer 2

• Short Chain Fatty Acids (SCFAs) liberated by the gut flora have been shown to:
  o Increase the secretion of appetite-curbing neuropeptides and gut peptides (e.g. GLP-2) which support the integrity of the intestinal lining.
• This is important as intestinal permeability is associated with ‘metabolic endotoxemia’ (a risk factor in obesity) characterised by:
  o Enhanced lipopolysaccharide (LPS) absorption.
  o Low grade chronic inflammation.
  o Insulin resistance.
  Metabolic endotoxemia = a persistent, sub-clinical, low-grade inflammatory response due to circulating endotoxins (mainly LPS).

Lipopolysaccharides = a component of the outer membranes of gram-negative bacteria.

Question 3

Metabolic endotoxemia

Answer 3

• Metabolic endotoxemia = a persistent, sub-clinical, low-grade inflammatory response due to circulating endotoxins (mainly LPS).

Question 4

Lipopolysaccharides

Answer 4

• Lipopolysaccharides = a component of the outer membranes of gram-negative bacteria.

Question 5

Pre and Pro biotics

Answer 5

• Modification of gut flora with pre-and pro-biotics is an important part of an effective weight management and metabolic health protocol.

Question 6

Gut flora and prebiotics

Answer 6

• Studies using prebiotics have been shown to:
  o Promote satiety.
  o Reduce hunger.
  o Reduce food ingestion.
  o Suppress ghrelin.
  o Increase peptide YY and GLP-1.
  Prebiotics = a non-digestible carbohydrate that promotes the growth of beneficial gut bacteria.

Question 7

Gut flora and probiotics

Answer 7

• Trials using probiotics have also shown success in metabolic syndrome:
  o One trial found a combination of diet and probiotic supplements (Lactobacilli and Bifidobacteria) was significantly more effective at lowering blood glucose levels and improving insulin sensitivity compared to dietary measures alone.
  o In another trial 4 weeks of L. acidophilus supplementation preserved insulin sensitivity, whereas it decreased in the placebo group.
  Probiotics = microorganisms introduced into the body for their beneficial health properties.

Question 8

Prebiotics

Answer 8

• Prebiotics = a non-digestible carbohydrate that promotes the growth of beneficial gut bacteria.

Question 9

Probiotics

Answer 9

• Probiotics = microorganisms introduced into the body for their beneficial health properties.