We spoke to TwinsUK researcher Dr Emily Leeming about her new book “Genius Gut: The Life-Changing Science of Eating for Your Second Brain” 

17th July 2024 – by TwinsUK

What inspired you to write “Genius Gut”?  

I wanted to share that what you eat can affect how you feel right now – how mentally sharp you feel, your mood, and how energetic you are. For too long the brain has been thought as separate to the rest of the body, and that’s not the case at all. And the gut has been hugely overlooked, it does so much more than just digest your food – it’s your second brain. It’s highly complex, containing its own nervous system, with more nerve cells than there are in your spinal cord. And its home to your gut microbiome, that can signal to your brain.

What is Genius Gut? 

Genius Gut is a book for everyone – if you have a gut and a brain, then this book is for you! It’s an easy guide to the science of the gut-brain connection, and our latest understanding of how gut microbes signal to the brain influencing mood, cognition and behaviour. There are ten simple hacks on how and what to eat for your gut bacteria, brainpower and to feel your best, packed with actionable tips and advice based on my research in nutrition and the microbiome at King’s College London, and as a registered dietitian. 

Can you explain the connection between our gut and brain in simple terms? 

It’s the science behind the phrases “gut feelings” and “I’ve got butterflies in my stomach”. For too long we’ve thought of the gut as only a food factory, when in fact it’s intimately connected with the CEO of your body – your brain. Your gut and your brain are physically connected through your vagus nerve, a long wandering nerve that reaches down from your brain to your upper body, including your gut. And your gut microbes can signal to your brain, through your vagus nerve, but also via metabolites, hormones and the immune system.  

What are some common misconceptions about the gut-brain connection that your book addresses? 

I wanted to highlight in Genius Gut how connected the brain and the gut really are. We talk about mental health and physical health as if they are two separate things. But we’re now understanding that many conditions and diseases of the mind can start in the gut or can be influenced by what we eat. Up to 80% of people with Parkinson’s disease also have constipation, that can appear as much as 20 years before movement and cognitive symptoms. In Alzheimer’s disease there’s a harmful build-up of mis-folding proteins in the brain, and there’s now early evidence in mice that these proteins could start in the gut first. You’re six times more likely to get Alzheimer’s disease if you have inflammatory bowel disease. And if you have irritable bowel syndrome, you’re significantly more likely to have anxiety and depression.  

How does the gut microbiome influence our mental health? 

Many people online claim that “90% of your feel-good serotonin is made in your gut”. While it’s true that 90% of serotonin is produced in the gut, this serotonin primarily helps with your digestion and it’s too large a molecule to pass through your blood-brain barrier to your brain. However, your gut bacteria do play an important role in helping your brain access the building blocks needed to produce your feelgood serotonin, as these smaller molecules can pass through the blood-brain barrier, for your brain to make serotonin itself.  

How does the gut microbiome influence our cognition? 

What microbes you have matters for your brain and cognition. For example, babies born via C-section initially receive their first batch of microbes from the hospital environment rather than from their mother. However, when these babies were given some of their mother’s vaginal microbiome for their guts, they had significantly better neurodevelopment at six months old than other c-section babies.  

Gut bacteria are linked to differences in the size of the hippocampus, memory and cognitive skills throughout childhood and adolescence, with the brain continuing to develop up until 25 years old. Microbes matter later in life as well, helping to lower excess inflammation that can damage the brain. In aging mice, a microbiome transplant from their more youthful counterparts improved memory and reversed signs of brain aging. Research from our department of Twins Research has also highlighted this connection between microbes and cognition. Colleagues found that a prebiotic fibre supplement, which feeds your ‘good’ gut bacteria, improved performance in memory tests in just three months. 

How has your personal journey influenced the insights and solutions offered in “Genius Gut”? 

What many people don’t know about me is that I spent the first part of my career as a private chef. So it’s important to me that food is delicious, and that there’s room for the occasional cake or chocolate too. I strongly believe we need to recognise the joy that food brings – and that how we think about food matters too – do you beat yourself up for enjoying a slice of cake, or do you savour it and move on? When we talk about the gut-brain connection we aren’t only talking about the gut talking to the brain, but also how the brain talks to the gut; how stress and mood can affect your food choices, your digestion, and your microbes. Healthy eating for your gut-brain connection is about balance. 

Dr Emily Leeming, Registered Dietitian and Research Fellow at Department of Twins Research and Genetic Epidemiology, King’s College London.  

Dr Emily’s book, Genius Gut: The Life-Changing Science of Eating for your Second Brain is available to buy now.  

You can also subscribe to her free weekly newsletter on Substack, called Second Brain 

Socials: @dremilyleeming 

The Link Between Gut Viruses and Cardiometabolic Disease 

21st February 2024 – By TwinsUK

A recent review published by researchers at TwinsUK sheds light on the potential role of viruses living in the gut, known as phages, in cardiometabolic diseases (CMDs).  

CMDs are a group of common and often preventable chronic diseases that affect the system of the heart and include type 2 diabetes mellitus, hypertension, cardiovascular disease, and non-alcoholic fatty liver disease.  They have been increasingly prevalent worldwide, with factors such as genetics, lifestyle, and diet contributing to their rise.  

More recently, the gut microbiome, a collection of microorganisms that exist in our large intestine, has also been implicated in CMDs. Interesting links have been found between bacteria and aspects of metabolic health, such as bodyweight, blood sugar and inflammation. However, the majority of existing research has focused on bacteria, overlooking other microorganisms such as phages. 

Phages are viruses that, instead of infecting human cells, infect bacteria cells, and in doing so play a crucial role in shaping bacterial communities within the gut, which in turn can affect human health. By infecting gut bacteria, phages can alter the abundance of bacteria, which may cause their levels to increase or decrease. Additionally, phages can change the way bacteria behave, for example by changing the metabolites that they release.    

Until now, studying the viruses in the gut has been challenging, which is one of the reasons why they have not been a focus of research. However, recent advancements are enabling researchers to investigate this potentially important but neglected aspect of gut health, with increasing interest being reflected in efforts such as the national Centre for Phage Research in Leicester, which aims to tackle a variety of global challenges through phages.  

Daniel Kirk, first author of the review, emphasises the importance of exploring the role of phages in CMDs: 

” As phages modulate gut bacteria communities, which in turn influence systemic health and susceptibility to cardiometabolic diseases, there is a need for a deeper understanding of how gut viruses contribute to cardiometabolic health.”   

To summarise what is currently known about phages in the gut microbiome in relation to CMDs, the authors searched for literature in this area. Across 15 studies, they found potential links between phages and obesity, type-2 diabetes mellitus, hypertension, and metabolic syndrome, amongst others. Their review highlights the potential involvement of phages in human health and provides information to inspire future research in the field, which is still at its inception and yet to be fully explored. 

The review also emphasises that harnessing the therapeutic potential of phages through phage therapy and faecal viral transplants could offer new avenues for treating CMDs. However, while the research is promising, more extensive studies and clinical trials are necessary to validate the efficacy of phage-based therapies in treating CMDs.

Lead author of the paper, Cristina Menni says:

“We highlight the broader implications of phage therapies beyond bacterial infections, extending to other diseases involving microbial imbalances in various organ systems.” 

What’s in a colon? New project ExHiBITT publishes first results

13th February 2020 – Paz Garcia

Even healthy people have abnormalities in their colon, according to the first results of new study ExHiBITT published today.

Researchers found that 28% of participants had polyps in the colon, which are small tumours on the surface of the colon lining that are typically detected in about a third of all colonoscopies. Researchers and doctors are interested in colonic polyps as in some cases they can lead to bowel cancer.

The colon is the last part of the digestive system and is a key location where microbes process any remaining solid waste before it is passed out as stool.

The aim of ExHiBITT – which stands for Exploring Host microBIome inTeractions in Twins – is to understand how our bodies interact with the billions of microbes in our colons.

The study was led by the Department of Twin Research in collaboration with researchers from Experimental Immunobiology from King’s College London and Guy’s and St Thomas’ Hospitals NHS Foundation Trust.

What did they find?

Over 200 healthy identical twins from TwinsUK took part in the study. The participants completed health questionnaires and provided samples including saliva, blood, stool and four colon biopsies obtained through a colonoscopy.

The researchers found that 28% of participants had polyps in their colon and 26% had previously undiagnosed diverticulosis, which is where small pockets form in the colon wall. People who have diverticulosis often do not feel any symptoms and the condition does not lead to cancer.

Participants with higher age and weight for their height (BMI) had a greater number of polyps, and if one twin in a pair had polyps, the chance of the other twin having polyps was 42%.

What’s next?

The team are now planning to study in closer detail the microbes identified in the samples to understand how it may influence our health. This includes analysing each participant’s metabolism and that of their microbes, as well as sequencing the microbes’ DNA. The researchers will use this information to create a rich database that will be available for other researchers to use, so that more health research can take place using the data generated by ExHiBITT.

Lead researcher Dr Marina Mora-Ortiz said:

“These findings are just the beginning and we’re now getting started on the next stage of analysing the collected samples. We’d like to say a huge thank you to our twins for taking part in this study, especially considering it involved a colonoscopy! We are always humbled by the contribution our selfless volunteers are willing to make to support medical research.”

Introducting ExHiBITT – Exploring Host microBIome inTeractions in Twins -, a colon multiomic cohort study (2020) Mora-Ortiz et al., Wellcome Open Research.

Gut bacteria need each other – and that affects our metabolism

3rd October 2019 – by Paz Garcia

Pile of lego bricks
Gut bacteria work together like Lego

Teamwork is key for the trillions of bacteria that live in our gut and this has a big impact on our metabolism, according to new research led by King’s College London, published today in Nature Communications.

The human gut is home to bacteria that help us digest our food, produce vitamins and perform many other tasks that influence our health.

Gut bacteria work together in groups to carry out different functions. The researchers, led by the Department of Twin Research & Genetic Epidemiology, found that this teamwork is much more important and more closely linked with our metabolism than individual species of bacteria.

The researchers studied the gut bacteria, blood and stool of over a thousand twins who take part in TwinsUK. This allowed the team to run the first large study on the link between gut bacterial species, their functions and the metabolism in the gut and blood of the participants.

The team found that while unrelated people share only 43% of gut bacteria species, they still share 82% of functions carried out by groups of gut bacteria. This is because different bacterial species can contribute to the same function and so different groups can work together to can carry out similar activities.

This research therefore suggests that health treatments designed to target gut bacteria – and our metabolism – should focus on groups of gut bacteria that carry out a particular function, rather than individual bacterial species.

Senior author Dr Mario Falchi explained:

“We can think of our gut bacteria like Lego bricks – the colour of the bricks doesn’t matter as much compared with how they fit together to make something. With gut bacteria, the individual species don’t matter as much as the group working together to carry out a function.”

“This is the first large study to explore the metabolic potential of the entire gut bacteria ecosystem. Our findings underline the importance of studying groups of bacteria and their functions overall, rather than focusing on specific species. These results add to the growing body of evidence that gut bacteria are intrinsically linked with human health.”

*

Visconti A, Le Roy CI, Rosa F, Rossi N, Martin TC, Mohney RP, Li W, de Rinaldis E, Bell JT, Venter JC, Nelson KE, Spector TD and Falchi M. Interplay between the human gut microbiome and host metabolism. Nature Communications (2019).

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