17 questions about gut health, answered by an expert
That the gut plays a central role in our existence has long been known. Over 2,000 years ago Hippocrates said "all disease begins in the gut", and countless phrases and proverbs since have reinforced the gut's position as an arbiter of wisdom and instinct.
While our gut instinct probably informed us what to put in our bellies over millennia, from the 20th century onward we've become increasingly detached from food, adding evermore tasty and addictive but nutritionally vacuous and chemically enhanced food into our diets.
This has had a damaging effect on gut health, and scientists across the world are beginning to discover just how important the gut microbiome, a universe of bacteria, yeasts, fungi, viruses and protozoans that live inside us – and weighs more than the average brain – is.
Tim Spector, professor of genetic epidemiology at King's College London and author of The Diet Myth: The Real Science Behind What We Eat, explains: "We've realised this collection of 100 trillion microbes inside us is acting as a community. Each one of those microbes is a chemical factory, digesting our food and producing thousands of chemical metabolites, vitamins and nutrients to help our bodies and control our immune system and appetites, our mood, our metabolism."
From IBS to allergies, obesity to heart disease, a myriad of health conditions can be traced in some way back to the gut (good work Hippocrates!). Yet, as befits such a nascent science, there's still a cloud of mystery surrounding gut health, especially in terms of public perception.
Which is why we asked Spector to clear up some pressing questions surrounding gut health. Here they are.
1. Why is it important to have a healthy gut?
It may be difficult to conceive, but our bodies contain more bacterial cells than human cells (40 trillion versus 30 trillion). After taking into account all the fungi, viruses and more, it's not surprising that a healthy gut is important.
"The gut contains a community of 100 trillion microbes that are crucial for our health, metabolism, weight control and immune system," says Spector. Born sterile, each human develops a unique microbiome from birth, a sort of bacterial fingerprint which helps you stay healthy.
2. How do I improve my gut health?
Diversity is key. Spector says the best way to improve your gut health is "by looking after your gut microbes – namely, increasing the amount and diversity of the plants and fibre you eat, increasing fermented foods like yoghurt, kefir, cheese and kimchi, and especially plants high in polyphenols."
Polyphenols are naturally occurring chemicals in plants which are considered antioxidants. A whole host of fruits, vegetables, grains, nuts, drinks, fats and spices contain polyphenols. Cloves, for example, came out top in one study, while dark chocolate, berries, beans, nuts and vegetables like artichoke, chicory, red onions and spinach all contain high levels.
3. Why is a varied gut flora important?
While it's great to eat plenty of fruit and veg, it's even better to eat a wide variety, because each different food will have different chemicals and nutrients. "The more diverse it is," says Spector, "the more chemicals they produce that protect you against diseases."
4. How do I increase the good bacteria in my gut?
The answer, for Spector, is simple. "By increasing diversity and avoiding junk food and antibiotics."
5. How do I get rid of bad bacteria in my gut?
"Squeeze them out by increasing the good guys," says Spector.
6. What are the biggest myths surrounding gut health?
There are plenty of myths and misconceptions around gut health. Not much is known about the long-term effect of probiotic supplements, for example, while there's still a belief in this country that bacteria are inherently a bad thing.
The biggest myth, says Spector, is "that everything is killed before it reaches the stomach. It isn't. Many millions of microbes get through."
7. What’s the difference between prebiotics and probiotics?
While having similar names, prebiotics and probiotics are rather different. "Prebiotics are foods that fertilise and feed good microbes," says Spector. "Probiotics are live microbes that help the body."
Foods that include plenty of prebiotics include chicory, Jerusalem artichoke, garlic, onions, leeks, asparagus, bananas, barley and oats. Probiotics are often found in fermented foods. Think yoghurt, kefir, sauerkraut, kimchi, miso, kombucha and pickles.
8. Will probiotic supplements improve my gut health?
Spector says that, generally, probiotic supplements can help with gut health. "But we don't know exactly which work best and in whom. Results may be as good as with some fermented foods."
As supplements tend to be pricey, getting probiotics through your diet is potentially preferable.
9. Are my digestive problems down to my gut?
"Most digestive problems involve gut microbes to some extent," Spector informs. Those suffering from issues like IBS, Crohn's or ulcerative colitis may benefit from improving their gut health.
10. What foods help with digestion?
"Fibre is the key to most gut problems, and on average we need to eat double our current levels," says Spector. Indeed, the average intake is 17.2g for women and 20.1g for men, whereas recommended intake is 30g.
Fibre is the bit not digested in the small intestine. Instead, it progresses to the large intestine or colon, where good bacteria ferments it. Foods high in fibre include wholegrain cereals, fruit, vegetables, pulses, nuts and seeds.
11. I have IBS, how can bacteria help me?
According to Mayo Clinic, "certain probiotics may relieve IBS symptoms, such as abdominal pain, bloating and diarrhoea."
Spector agrees: "Most sufferers have abnormal microbes and should try different diets and supplements to modify their microbiome and help symptoms."
12. What health issues are linked to gut health?
"Nearly every disease we have looked at has been implicated," says Spector. "Some gut problems may be caused by the disease, while others may be caused by a disorder of the microbes, such as obesity, diabetes, depression and anxiety, IBS, food allergies, autism, eczema, Crohn's, ulcerative colitis and many immune diseases."
13. Fermented foods are supposed to be good for me, but what about bread, cheese, beer, wine, and what about the bacteria on things like jamon iberico?
The good news is that foods containing plenty of healthy bacteria are not limited to fruit and veg; many more indulgent treats can be beneficial too (though, of course, they come with other pitfalls).
"Bread is not fermented as the bugs are killed by baking, but real bread, especially sourdough or rye bread, has plenty of fibre and is gut friendly. All real cheese is good, especially raw milk varieties," explains Spector.
"Beer is fairly neutral, though ales contain lots of polyphenols, and red wine especially is good for the gut in moderation.
"Some salamis, if made artisanally, contain probiotic microbes and may be beneficial. Even dark chocolate, though not probiotic, contains polyphenols and if over 70 per cent is good."