Everything You Need to Know About the Gut Microbiome

Everything You Need to Know About the Gut Microbiome

We asked Dr Chris George to answer our pressing questions and give us the lowdown on all things gut microbiome. Are you ready?

The gut microbiome is a diverse collection of organisms that live mainly within our large bowel and have an important role in many of our body's functions including digestion, immunity and metabolism.

What are the best ways to support our gut microbiome and what should we try and avoid?
  • Add lots of colourful plants as they are packed full of polyphenols which nourish the ‘good’ gut microbes.
  • Try adding fermented foods to your diet as they contain gut friendly bugs which may increase the number and diversity of bacteria within your microbiome.
  • Limit ultra-processed foods as these can negatively impact the gut microbiome and lead to inflammation.
  • Eat more plants as this provides dietary fibre which feeds the gut microbiota, keeping them diverse and healthy.
  • Physical activity can positively impact your gut microbiome as well as having both mental and physical benefits on our wellbeing.
  • Reduce artificial sweeteners as these can reduce the number of good bacteria in the gut known as ‘dysbiosis’.

Are we more bacteria than human?
  • The gut microbiota weighs on average 200g for a 70kg adult – this is equal to a mango.
  • 95% of our gut bacteria is located within our large intestine and is thought to be one of the most heavily populated microbial ecosystems in the world.
  • There are more than 10-100 trillion different microorganisms that make up our human microbiota
  • On balance you’re probably made up of more microbes than you are human cells!
  • The gut microbiome is the genetic material of all the microbes – bacteria, fungi, protozoa and viruses - within one person’s gastrointestinal system.

Can you tell us about serotonin and the gut?
  • Have you ever felt butterflies in your stomach or been told to ‘trust your gut feeling’? It’s likely that you have been receiving signals from an unexpected source sometimes termed your ‘second brain’.
  • The gut has over 500 million neurons that form the enteric nervous system`. It uses 35 different types of neurotransmitters, just like the brain.
  • Serotonin is a neurotransmitter that sends messages between cells – it has a role in many functions including emotions and happiness, as well as digestion.
  • Gut bacteria produce 95% of our body’s supply of serotonin.
  • Serotonin receptors (5HT3 and 5HT4) found within the gut nervous system are involved in motility, secretion and even pain which may play an important role in bowel conditions such as IBS.

Are 70% of our immune system cells really located in our gut?
  • The gut microbiota plays a fundamental role in the training and function of our immune system.
  • Gut-associated lymphoid tissue (GALT) is the largest immune system in the body.
  • 70% of our immune cells are located in the gut as part of the GALT.

Does the human gut really contain 10-100 trillion bacteria?
  • The gut microbiome has more microbes than the number of stars that have been counted in the Milky Way galaxy.
  • To put this in context the gut microbiota has 10-100 trillion microorganisms and the Milky Way 100-400 billion stars.
  • There are more microbes in our gut than stars in the Milky Way galaxy.
  • Your microbiome may have more genes than the universe has stars.