Our modern diets and lifestyles can trigger the overgrowth of bad bacteria in the gut. Photo / 123RF
With 80 per cent of our immune system within our gut, it’s worth paying attention to the causes of inflammation to overhaul our health.
In recent years, gut health and inflammation have become such popular buzzwords that most of us know that they are vital to our health. Yet many still don’t realise just how intricately they are linked.
The gut microbiome, or bustling community of trillions of microbes living deep within our intestines, is often called “the second brain”. Scientists are now realising that when this community is out of balance, when the bad bacteria have begun to dominate and kill off the good, this can set off a toxic chain reaction throughout the body. This is chronic inflammation and can be a root cause of many of our most serious illnesses, from cancer to heart disease and diabetes.
“We do need some inflammation in the body when it’s in response to an infection or acute injury. It’s there to heal us and do a job,” says Dr Emily Porter, a specialist gut dietitian at The Gut Health Clinic in London. “What can become a problem is chronic low-lying inflammation, and this has a direct bidirectional relationship with gut imbalance,” she says.
Inflammation is the activation of our immune system, and the reason that the gut is so intimately linked to inflammation is that up to 80 per cent of our immune system lies within our gut.
Jack Gilbert, a professor of paediatrics at the University of California, San Diego, says: “To extract nutrients from the outside world, we have to be open to it, so imagine human beings to be like long doughnuts with a hole stretching from our mouths to our anus. Foods pass from our mouth to our intestine, and our immune system has developed especially inside the intestine so it can manage what is coming in. It is like an active gardener, managing our gut microbiome garden to grow fruit and vegetables and get rid of weeds.”
The problem is that our modern diets and lifestyles can trigger the overgrowth of bad bacteria that, in turn, trigger the immune system to overreact, even if no injury or infection is present.
“These bad bacteria are good at firing up the immune system to think there is an infection and overreact,” says Gilbert, “so now you get massive inflammation in your gut, and it gets into the bloodstream and the lymph system so you can end up with joint pain, fatigue, depression, anxiety, allergies, cardiac health problems, asthma and more – it can cause a myriad of problems throughout your system.”
Chronic inflammation can cause multiple symptoms, but unfortunately low-grade inflammation might also have no symptoms at all. “There might be no obvious external signs. It’s quite possible, for example, that a lot of children who have a poor diet, don’t get a lot of exercise and suffer from external pollution and stress, could be suffering from low-grade inflammation,” says Gilbert.
If you do have symptoms, they can be wide-ranging. “Depression and anxiety can be symptoms because your brain is connected to your gut, and systemic inflammation can create a negative feedback loop. Skin rashes, fatigue, joint aches, wheezing, shortness of breath and more can all be a result of inflammation in the body. Feeling bloated could be a sign of inflammation if it doesn’t get better from passing wind,” he adds.
Porter adds that symptoms might include “belching, flatulence, feeling tired because vitamins and minerals aren’t being absorbed properly, and changes in bowel habits. If someone comes to the clinic with gut symptoms, we’ll look at the person’s health as a whole to try and unpick the causes, and work out whether they need to see a doctor to rule out a potentially more serious condition.”
Here are the nutrition tips you should follow for the best results.
Get lots of fruit and vegetables
To maintain a healthy balanced gut microbiome and reduce inflammation, we need to eat much more fibre than most of us do now.
“In our modern world, we don’t consume enough fibre,” say Gilbert. “We need about 50-60 grams a day. This is complex, but basically when bacteria consume plant fibres they release a chemical called butyrate, which is a short-chain fatty acid, a prime fuel for our immune system. If the immune system doesn’t get butyrate it’s like an army not getting enough food, and that’s when you get this chronic inflammation.
“So we need to consume a diverse array of plant fibres – 30 species a week should get you enough plant diversity, and remember that broccoli, sprouts and cabbage are from the same plant species, for example. But very few of us do that. Instead, we eat a lot of saturated fat, a lot of protein and a lot of simple sugars and processed food in our Western diets,” says Gilbert.
Eating 30 different plant foods feeds and encourages a wide range of healthy gut bacteria to grow and flourish. According to Dr Emily Porter: “All the different strains of bacteria have different favourite foods that they use to produce short-chain fatty acids that are beneficial for us and anti-inflammatory. Studies have shown that eating 30 plants a week will also add years to your health span – the period of your life in which you remain healthy.”
Eat a wide range of food types
“I encourage people to eat what we call the ‘super six’,” says Porter. “That’s fruit, vegetables, wholegrains, nuts and seeds, beans and pulses, and herbs and spices. If people are eating across these six food groups, we know that is associated with good gut health. Basically if you stick to a Mediterranean-style diet you can’t go far wrong, and that means adding in lean protein like oily fish as well and red wine in moderation,” she says.
Porter also recommends expanding our dietary choices beyond the standard options we always reach for.
“Eat prebiotics like onions, garlic and leeks, brightly coloured fruits and veg, and especially beans and pulses – they’re my hero foods. Try to add in rather than take away – so oats are good, but add in a seed and nut mix to make them even more nutritious. Brown bread is good, but if you go for a granary style you’re going to get a bit more fibre, protein and seeds as well. Rather than just having brown pasta, try quinoa, bulgar wheat, wholegrain couscous and buckwheat. The key thing is diversity,” she says.
Include fermented foods in your diet
Numerous studies have shown that fermented foods like kimchi, sauerkraut (pickled cabbage), kefir (fermented milk), kombucha, live yoghurt, pickles and miso are incredibly valuable for your gut health.
“Research has shown that to get the most benefit from eating a high-fibre diet, you have to prime the microbiome with a fermented food diet,” says Gilbert. “We’re not entirely sure why, but we think it’s because fermented foods contain a lot of bacteria that our ancestors used to consume, as they didn’t have fridges to preserve things. So our immune systems, which keep a record of everything they see, say, ‘Oh, I know these guys, they’re safe,’ and we have this amazing situation where they dampen down inflammation and encourage the proliferation of good bacteria in our gut.”
Eat foods rich in polyphenols
There is growing evidence showing that dietary polyphenol may directly modulate the gut microbiome, increasing beneficial microbial species or decreasing harmful ones. High quantities of polyphenols can be found in all berries, carrots, cocoa, 70 per cent dark chocolate, tea and coffee, beans, green tea, olives and soy.
“If you eat the rainbow by choosing lots of different-coloured foods, you’ll be eating ‘polyphenols’, a beneficial chemical found in highly pigmented foods. Polyphenols are loved by our gut bacteria, and transformed by them into helpful anti-inflammatory chemicals,” says Porter. Polyphenols are also good for blood sugar control and may reduce the risk of heart disease.
Limit ultra-processed foods
Processed foods aren’t very nourishing for your gut as they tend to contain a lot of fat, sugar, salt and preservatives. “There are suppressed levels of nutrients associated with those foods as they’re generally processed to make them more shelf stable,” says Gilbert. “They’re good at providing us with calories, but not the nutrients that our bodies need. A lot of processed foods also promote the growth of bacteria that love simple sugars, and you end up with too many bad bacteria growing, encouraging inflammation.”
Porter emphasises that it’s about finding a balance, rather than cutting foods out altogether. “We don’t want to demonise food. Food is about more than health, it’s celebration, it’s social and it’s connection. Generally, we advise having less of those [ultra-processed] foods, or just having them once in a while or balancing them with healthier additions. So, for example, if you’re having a croissant for breakfast, maybe have some strawberries with it.”
It’s not just a poor diet that can imbalance our gut – our lifestyles, including stress, sleep and exercise, also play a major role. Our brain and our gut are in constant communication, so if we feel stressed or anxious that will impact on the gut, and similarly if the gut is inflamed that can also make us feel depressed.
“We’ve done studies that have shown that stress induces inflammation throughout the body,” says Gilbert. “We looked at farmers who go through periods when they are making money and periods when they are quite poor, and during the periods when they are poor, their bodies become inflamed because of the stress caused by worrying about money. Then, when they have money, their bodies go back to normal. Psychological stress causes your brain to release the hormone cortisol, which changes how your immune system works and promotes the growth of bad bacteria. Then, of course, when you’re stressed you’re more likely to eat bad food, and it’s a continuous cycle.”
When it comes to exercise, we’ve evolved to do this daily, so it’s not enough to go to the gym once a week. That exercise also promotes the growth of good bacteria, which dampen down inflammatory responses. Exercise is also brilliant for stress. Sleep allows our body to recover and repair, and makes it less likely we’ll eat badly and get stressed as well.
The lesson of the gut is that everything is connected – we can’t cheat on our mental or physical health.
Bad
White sliced bread
Not so bad
Wholemeal breads, although they may contain preservatives for longer shelf life, they are a good source of slow-release carbs and fibre
Bad
Sweetened cereals like Coco Pops and Frosties
Not so bad
Wholegrain breakfast cereals with higher fibre and lower sugar, like no-added sugar Alpen and Multigrain Cheerios
Bad
Frankfurter: Avoid sausages made from highly-processed meats
Not so bad
Fish fingers, a good source of protein and omega-3 and popular with kids
Bad
Deep pan pepperoni pizza
Not so bad
Thin crust with a vegetable topping
Bad
Carbonara pasta sauce: Creamy sauces are more likely to contain emulsifiers and thickeners and the meat would be highly processed.
Not so bad
Tomato-based pasta sauces: These can help you reach your 5-a-day and are a good source of the antioxidant lycopene, choose low/sugar low salt
Bad
Low-fat, sugar-free fruit yoghurt
Not so bad
Low-sugar, full-fat fruit yoghurt, look for those with under 5g sugar/100g
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