Why your gut health should be a priority in 2024

With the feasting and fun of the holiday season behind us, January can feel like a good moment for a healthy reset. But rather than fixating on the latest diet, we can profoundly influence our health (and weight) by encouraging a community of diverse gut bacteria. Read on to discover what the latest research says about the importance of the trillions of bacteria living inside us. 

What is the gut microbiome? 

Deep within our intestines is a large and thriving community of bacteria, fungi and viruses collectively known as our gut microbiome. There are trillions of these tiny microbes and they can collectively weigh between 1-2kg, roughly the same as your brain. 

The complexity of the gut microbiome is a relatively recent discovery, and increasingly scientists are realising that this organ, known as the “second brain”,  is a vital player when it comes to our wellbeing, influencing everything from our immune systems to our mental health. 

Dr James Kinross is a surgeon at Imperial College London, a microbiome scientist and the author of Dark Matter: The New Science of the Microbiome. “We discovered it – or rediscovered it – in the 2000s with genetic sequencing. What we learnt is that it’s an entire organ in its own right, and that this organ has lots of very important functions when it comes to regulating our day-to-day health,” he says. “That is in part because it communicates with our immune system, but it’s also critical for maintaining the health of our other organs. If you have an unhealthy microbiome, it significantly influences your chance of getting chronic diseases like diabetes, asthma and Alzheimer’s in later life.” 

Yet modern lifestyles and diets have not been kind to our guts. Processed food, stress and antibiotics have killed off healthy bacteria and encouraged the growth of toxic ones, leading to an imbalance and, ultimately, chronic disease and illness.

“I describe this as like an internal climate crisis – we’re losing the biodiversity of our internal ecosystem,” says Kinross. “Antibiotics have profoundly altered our microbiome in a very short period of time, but 80 per cent of antibiotics are used in farming practices, so it’s also about the industrialisation of our diet. But it’s not just that: the food we eat is very important, as is urbanisation and pollution.” 

The good news is that everyone’s gut microbiome is unique and constantly evolving, so we can improve its diversity with the choices we make. 

How does the gut affect your whole body?

In the first instance, the gut absorbs and transforms the food that we eat to sustain our body with calories, vitamins and minerals.  

“The importance of digestion stands alone,” says Dr Will Bulsiewicz, a gastroenterologist, author and US medical director of the health app Zoe. 

“Digestion is life – we can’t live without access to nutrients. And yet I don’t just want people to think about digestion and poo when they think about the gut. I want people to think about the immune system, metabolism and the brain because the things that are happening in the digestive system have a direct impact throughout your body. To simplify it, the microbes in our gut create these chemical compounds called bioactives, and these compounds interact with the brain, the organs and the immune system. To be honest, you could write a book on each one of these systems,” he says. 

The immune system, in particular, has a very close relationship to the gut. “Most people don’t realise that 70 per cent of your immune system is actually centrally located within the wall of your intestine, and the systems are in such close proximity to one another that they are in direct communication. Yet there is just one layer of cells between them and that can easily be broken, which means toxins can come into contact with the immune system and trigger inflammation,” says Bulsiewicz. 

Kinross explains it as “the gut being a sort of command and control centre of your whole immune system. This is all about your immunity and inflammation. Because if you’ve got the wrong type of bugs, you can’t regulate the inflammation, and that affects everything – how your brain works, how you think, how you feel, how your lungs work, your bladder, joints and bones – and that is because chronic inflammation is systemic, by which I mean it is throughout your whole body.”

How does the microbiome affect your health? 

An imbalanced gut can not only lead to gut health conditions like IBS, bloating and Crohn’s, but is also a major factor in many leading causes of disease. 

“If you were to go and look at the top causes of disease in the West, you would be quite shocked by what percentage of them are inflammatory conditions. From rheumatoid arthritis, obesity, eczema, allergies and heart disease, which is our number one killer, to strokes, cancer and diabetes – nearly all of these major health conditions have some level of inflammation involved,” says Bulsiewicz. 

Imbalance in the gut is also linked to mood and mental health conditions. “People don’t know that 70 per cent of serotonin – the happy hormone – is produced in the gut,” Bulsiewicz continues. “In the Smiles trial, people with major depression were put on a plant-heavy Mediterranean diet that was high in fibre and they saw significant improvements in their mental health. Gut health is not the only thing that matters, but it’s definitely part of the story.”

Bulsiewicz also points to a study in the journal Cell that linked gut health to long Covid. “Researchers discovered that the guts of people with long Covid were actually producing less serotonin, so we know that there is this important connection between gut health and the brain.” 

Top 7 ways to improve your gut microbiome

Get vaccinated and avoid antibiotics (when possible) 

“Antibiotics are a vital part of modern medicine, but minimise them if possible, as well as the medication you don’t need to be on, because we know that a quarter of medicines have an antibiotic effect on the gut,” says Kinross. “Common painkillers like ibuprofen cause inflammation in the gut, and antacid medicines also influence the gut microbiome in unhelpful ways. Get vaccinated as we know that’s an effective way to stay healthy. People who get viruses such as flu and Covid who aren’t vaccinated are much more likely to take antibiotics.” 

Ditch a fast-food-style Western diet 

“Foods that are high in saturated fat, refined sugars and are ultra-processed really damage the gut in quite a profound way. The best thing to do is to avoid them as much as possible,” Kinross advises.  

Encourage a diverse gut by eating a diverse selection of plants

“Generally speaking, a higher level of diversity is associated with better overall health. The more diverse your gut microbiome, the greater the breadth of skills it possesses, and this increases your resilience to infection,” says Dr Megan Rossi, dietitian, founder of The Gut Health Clinic and a research fellow at King’s College London. 

Eat 30g of fibre a day 

Your gut loves fibre, and generally most of us don’t get enough of it. “The majority of your nutrition should come through plant-based foods, which doesn’t mean you have to be vegetarian but does mean you should get 30g of fibre a day,” says Kinross. A study in The Lancet found that adding just 8g of fibre to participants’ daily diets led to reductions in the risk of heart disease, Type 2 diabetes, colon cancer and death from all causes. 

Socialise and stay connected to others 

Spend less time on devices and social media and more time with your real-life social network. “Social isolation affects the robustness and diversity of your ecosystem,” says Kinross. “It’s important to be meaningfully connected. When you hold hands, touch or share the preparation of food, you’re exchanging beneficial microbes. As our families and social networks get smaller, our guts get less diverse. Teenagers with big social networks have a more diverse microbiome.”  

Manage stress 

“Try to exert some kind of control over stress. We’re all human and things can get crazy sometimes, but finding ways to manage stress is a lever we can pull to really get to the root cause of some of these gut inflammation issues,” advises Bulsiewicz. Meditation, exercise, socialising and time in nature are all helpful. 

Exercise regularly – preferably with others

“Exercise is an incredibly important way to improve your health, and what I recommend to my patients is to exercise socially as it’s better for your mental health. The gut and the brain talk to each other and it’s a two-way conversation, so looking after your brain will help your gut and vice-versa,” says Kinross. 

What are the best foods for your gut microbiome?

Eat a rainbow of vegetables 

“Vegetables contain fibre and water and have multiple health benefits. The different colours represent different phytochemicals which have antioxidant and anti-inflammatory properties that enhance our gut,” says Dr Leke Asong, an NHS GP, functional medicine doctor and gut health expert. 

Eat polyphenol-rich foods like blueberries and olives

One of the most important of the phytochemicals is polyphenols – which are transformed by our guts into beneficial chemicals. Polyphenols can be found in many foods including green tea, dark-coloured fruit and extra-virgin olive oil.

Eat wholegrains like oats, quinoa and bulgur 

Wholegrains that haven’t been refined are packed full of fibre and great for our gut. “These are not just great for gut health, but there is also some convincing evidence that they can reduce your chances of developing certain diseases including diabetes, heart disease and several cancers,” says Rossi. 

Eat fermented foods that contain live bacteria

“These are really important as they contain natural, good bacteria,” says Asong. There are many different fermented foods, but among the most popular are Greek yogurt, spicy Korean kimchi and the drink kombucha.

Gut health FAQ 

What is the difference between probiotic and prebiotic supplements?

Prebiotics are the foods that bacteria feast on, and probiotics are the bacteria themselves – yet most doctors advise prioritising food over pills. “Before taking supplements, we should try to get as much as possible from food – prebiotics are found in the fibre and starch we get from plants. For probiotics we would find these bacteria in fermented foods and raw vegetables, all of which have their own microbiome,” says Bulsiewicz. 

“That said, we do have studies that demonstrate supplements can be beneficial as an addition to a balanced diet. In terms of the prebiotics, I would want to see research on human studies backing up the claims. When it comes to probiotics, I think it’s worth researching which probiotic has evidence for a particular condition,” Bulsiewicz explains. “If you have IBS, for example, look for a probiotic study that works for that condition. Then it’s about trial and error. Try it for four to eight weeks and see if it’s worth your money.” he adds. 

Are faecal transplants worth trying for gut disorders? 

Faecal microbiota transplantation (FMT) is an emerging treatment that is now offered on the NHS in limited cases for patients with ulcerative colitis, where the gut has become severely inflamed. Gut bacteria is taken from the faeces of healthy donors and introduced to a patient’s intestine.

“Faecal transplants are an exciting new area of research and are becoming more accepted as a medical therapy. There are well over 400 research trials currently going on for a range of conditions, yet it is still an experimental therapy and should not be tried in non-regulated clinics, and only done in the context of a hospital or clinician,” explains Kinross. 

Does the gut microbiome affect weight? 

Generally speaking, a healthy gut will lead to a healthy weight. “Some bacteria are shown to have anti-obesity properties. The gut also produces vitamins and hormones that aid in maintaining a healthy weight. An imbalanced gut produces less of the serotonin hormone, which can lead to sugar cravings to fill the void,” says Asong.  

The principles of eating healthily and avoiding sugar and fast food will help to balance your gut and lead to a healthy weight. 

What kind of CFU (the number of bacteria) should your supplements contain? 

“A minimum of 1 billion CFUs would be a good number,” says Asong. “That said, people shouldn’t get hung up on the number. The ultimate strain of probiotics depends on what we want to achieve. Some strains have been linked to immunity, some to obesity, some to skin health and so on. 

“A PCR stool test does help fine-tune the process. Remember, we are all different and our microbiome is constantly changing.” 

How many species of gut microbiota do you need for good gut health? 

“There is no consensus on this,” says Asong. “As a general rule, the greater the diversity of microbes, the better. If diversity is the goal, the best strategy is to eat a variety of fermented foods. That said, if you have a poorly gut and a stool test shows a deficiency in a specific group of bacteria, a probiotic supplement could be the way to go.”