Gut Microbiome (HL)

Microbiome: a collection of genomes from all microorganisms in the environment

Microbiota: refers to microorganisms including bacteria, viruses, fungi and parasites found within specific environments

 

Important Roles of the Gut

Extracts and synthesises nutrients from the food you eat

  • Absorbs minerals

  • Produces fatty acids to strengthen gut barrier

Provides defence

  • Prevents overgrowth of pathogens

  • Inhibits growth of less desirable bacteria

  • Interacts with immune system for protection

Neurotransmitters are secreted from the gut

  • Target area in brain for mood regulation and cognition

 

Factors Affecting Gut Microbiome

Diet:

  • Dietary Fibre

  • Fermented Foods

  • Polyphenols

Lifestyle:

  • Physical Activity

  • Sleep

  • Stress

  • Smoking or Drinking

Genetics

Medication:

  • Probiotics

  • Antibiotics

 

The following components collectively can improve gut microbiome health, digestion and overall well being:

Dietary fibres: is a food source for the beneficial bacteria in the gut, helping their growth and promotes healthy digestion

Polyphenols: found in plant-based foods, promote the growth of beneficial gut bacteria and inhibit the growth of harmful bacteria, also reduces inflammation

Fermented foods: rich in probiotics, these foods introduce live beneficial bacteria into the gut, improving microbial balance, supporting digestion and potentially enhancing immune function

 

Antibiotics vs. probiotics

Antibiotics: destroys bacteria (harmful and beneficial), often leading to gut dysbiosis (microbial imbalance)

Probiotics: reintroduce and support beneficial bacteria, promoting gut health and restoring balance

Effects on the Gut

  • Antibiotics often disrupt the gut microbiome by killing both harmful and beneficial bacteria. Probiotics replenish the beneficial bacteria, restoring balance

  • Improving Digestion: they enhance the breakdown of food and absorption of nutrients

  • Reducing Gastrointestinal Disorders: probiotics can help manage conditions such as diarrhea, irritable bowel syndrome and inflammatory bowel disease

 

Effects of Probiotics on Overall Health:

Immune System Boost: about 70% of the immune system in the gut. Probiotics enhance immune responses by interacting with gut-associated lymphoid tissue (GALT)

Mental health: through the gut-brain axis, probiotics may influence mood and mental health by producing neurotransmitters like serotonin

Metabolic Health: regulate metabolism, improve insulin sensitivity, and reduce the risk of obesity-related conditions

Reduction of Chronic Inflammation: promotes anti-inflammatory signals, contributing to lower systemic inflammation, which is a root cause of many chronic diseases

Allergy and Skin Health: reduce allergies and improve skin conditions like eczema by modulating immune responses

 

Digestion

Nutrients are extracted from the foods we eat

Most nutrients are absorbed in the small intestine

Any nutrients that aren't absorbed in the small intestine move into the large intestine where it is broken down by microorganisms

These microorganisms release metabolites including vitamin B and vitamin K

--> they are absorbed or act they act as strong signals to your brain, nervous system, immune system and blood circulatory system

 

Signals sent from our gut

When our gut is nearly empty a signal is sent to the brain

When our gut is full the opposite signal is sent

The gut also sends other signals when harmful pathogens are present

Gut microbiota is responsible for triggering and modulating many of these signals by stimulating the release of hormones or neurotransmitters

 

The gut-brain axis

Two way communication system between the gut and brain + spinal chord

Extends to include endocrine, humoral, metabolic and immune routes of communication

--> allows information to be exchanged simultaneously

--> influences mood, cognition and mental health

Undesirable gut microbiota are linked with changes in gut wall permeability

--> allows bacteria to move from one location to another

Infections can spread from the gut to the bloodstream to attack immune systems

--> need to keep the gut membrane strong to prevent this

RED-S is a conditions caused by an imbalance between energy intake and energy expenditure

--> present in athletes engaging in high-intensity training

Leads to health issues such as gastrointestinal (GI) complaints

 

RED-S and GI Complaints

Reduced blood flow to the gut: low energy availability can reduce blood flow to the GI system

--> impairs digestion and absorption of nutrients resulting in bloating, abdominal pain and constipation

Altered Gut Motility: chronic energy deficiency may disrupt motility

--> slow digestion or irregular bowel movements

Gut Barrier Function: RED-S may impair the integrity of the gut lining, increasing intestinal permeability

--> contributes to inflammation and GI discomfort

Impact on Nutrient Absorption: insufficient calorie intake and reduced digestive efficiency can decrease the absorption of essential nutrients, further exacerbating GI systems.

 

How does RED-S affect Gut Bacteria?

Reduced Diversity in the Microbiome

  • A well balanced diet maintains a diverse gut microbiome

  • RED-S reduces the variety of nutrients available to gut bacteria due to insufficient dietary intake

Increased Inflammation

  • Trigger systemic inflammation due to increased intestinal permeability

Altered Metabolite Production

  • Energy deficiency reduces production of short-chain fatty acids which play a role in gut health, reducing the gut lining

Hormonal Disruptions

  • RED-S associated with hormonal imbalances which can alter the gut microbiota composition

Stress on the Gut

  • High training loads with insufficient recovery adds stress on the gut, disrupting microbiome balance.

 

Mitigating the Effects of RED-S on Gut Health

  • Adequate energy intake: meet energy needs through balanced diets

  • Probiotics and Prebiotics: includes foods like yoghurt or fibre rich fruits and vegetables to restore/maintain microbiota diversity

  • Gradual Reintroduction of Nutrients: to increase energy intake

  • Hydration: maintain proper hydration

  • Monitor Training Load: ensure adequate recovery to reduce stress on the gut