For such a well-studied system of organs and processes, there’s still a great deal that science has yet to uncover about the human body and one of the most intriguing areas of modern study is the role of the gut in human health. The digestive system, and the trillions of bacteria that form the gut microbiota, are understood to play a role in health and wellbeing. However, the full extent – along with the precise mechanisms of action – are still not fully understood. 

In research laboratories around the world, we are building better understanding of the complexity of the gut and how it may influence other parts of the body. One key area of focus is the relationship between the gut and the immune system.

At Clasado Biosciences, we have recently recorded and released a Table Talk podcast, as part of a Food Matters digital event. 

The podcast is hosted by author and broadcaster Stefan Gates, and features guests Dr Caroline Childs, lecturer in Nutritional Sciences at the University of Southampton, Gemma Walton, lecturer in Metagenomics at the University of Reading and Dr Lucien Harthoorn, Research and Development Director at Clasado Biosciences.

We transcribe here six of the key learnings from the podcast outlining the current understanding of the gut microbiome and its interplay with the immune system. 

Our microbiome is initially formed through diet in early infancy

Gemma Walton

“The bacteria in and on us do change throughout our lives. When we are born, we get our first big microbial meal. We’ll get bacteria introduced into our bodies from this, and the bacteria are going to grow up, use oxygen rapidly in the intestine, and then we’re going to get an environment suitable for the growth of bacteria without oxygen. That means we get bacteria growing up that don’t use oxygen very much. 

As an infant we have the option of breastfeeding or formula feeding. We can see differences in the microbiota of individuals that are breast-fed versus formula-fed. Those infants that are breast-fed have a greater abundance of a bacteria genus called bifidobacteria. This group of bacteria are associated with positive health effects. 

[Find out more about bifidobacteria here]

Breast-fed infants tend to have a greater diversity of bacteria and a higher amount of bifidobacteria as well, whereas formula-fed infants seem to have a lower amount of bifidobacteria. We see differences and breast-fed infants are actually linked to having fewer gastrointestinal infections.“

We can influence the bacteria in our gut microbiome

Gemma Walton

“There are a few ways we can specifically influence our gut bacteria. We can take supplements that support our gut bacteria. One example could be a prebiotic, which is a food that feeds and fuels our gut bacteria. There are no bacteria in prebiotics; it’s an ingredient that gets to our large intestine and is then used by the bacteria that resides there. It can increase the activity or number of positive bacteria in the gut and that could have a beneficial effect on health. 

Prebiotics are also naturally occurring, one of the best examples of a natural prebiotic is breast milk. Other examples we find in vegetables including things like chicory root; Inulin is found in high amounts in chicory roots. We’ve also got things like bananas, garlic, Jerusalem artichokes, even dandelion leaves – so you can find them occurring quite naturally in some parts of the diet.”

There is a connection between the gut and the immune system

Dr Caroline Childs

“Think about the challenge we put on our immune system every day. Each of us eats 1-2kg of food per day and our immune system is constantly working out “Is this something safe, which we should allow to continue being absorbed, or have you just eaten Salmonella and I need to start making you vomit and have diarrhoea as quickly as possible?”

Equally, we have to detect, is this a safe food? If our immune system gets it wrong, you may have a peanut allergy for example, and your body is responding to something that you would hope it might leave alone. 

Our immune system has a huge job to do in correctly responding to danger in the food that we eat, without over-responding. So, we have these massive links between what’s in our gut, and our immune system. Immune cells are influenced by the bacteria that we have in our gut, and the chemicals that they make as part of their normal life span processes, as well as those interactions that they have directly with our immune system.”

There are benefits to supplementary prebiotics over naturally occurring prebiotics found in food

Dr Caroline Childs

“I think it’s certainly possible to get something which is a higher prebiotic dose through a supplement compared to a food stuff. Ideally, we would hope that people have a healthy balanced diet, but in reality, that might be hard to achieve. And there may be certain circumstances where you’d wish there were extra interventions available. 

One example might be people who are hospitalised and have been taking antibiotics. We know that giving them a probiotic supplement can reduce their chance of having diarrhoea, a consequence of taking the antibiotic, by about half. So that might be an effective time in which targeted supplements are very useful.”

Gemma Walton

“A well-balanced diet can be very helpful, but I like the specific nature of prebiotics and probiotics as well. With a prebiotic, you’re know you’re specifically targeting positive bacteria within the large intestine. With a probiotic, you’re adding a very specific gut bacteria for the large intestine which might have a positive effect, and with a prebiotic you’re targeting certain groups of bacteria. So, while you can get prebiotics from a balanced diet, you know that you’re being more specific with what you’re targeting with supplements.”

Click here to read part two.

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