It’s a fascinating area of scientific research and intricately linked to our overall health, but how much do we really know about our gut? If you ask leading science journalist Michael Mosley, he’ll tell you the body’s “second brain” certainly is clever – microbes in the gut protect us from obesity, cancer and other diseases, boost our immune systems and can even assist in weight loss. No wonder everyone’s suddenly so interested in how to take care of it properly.
Mosley dropped into SBS ahead of his appearance on Insight last night to answer your questions about guts through Facebook live video. If you missed it, here’s what Mosley had to say about the how caffeine affects the body, the possible links between brain health and gut health, and why our newfound obsession with fermented foods is actually a pretty good thing.
I’m here now to take your questions about the gut and about gut health. The first one we’ve got here is from Rosie. How does caffeine impact our guts?
It’s not so much the caffeine as coffee, because coffee has all sorts of antioxidants and other things in it. It turns out that these phenols and various things, these things are very good for your gut. The substances that you find in coffee and also cocoa tend to be quite good for the gut. That’s encouraging, isn’t it?
I consume quite a lot of coffee, four or five cups a day. It’s been linked in big studies to reduced risk of death, strangely enough. Particularly suicide, I don’t know why, but it seems to improve mood. So I’m very happy to consume caffeine, and my gut seems to be very happy with caffeine as well.
That said however, there are a number of foods which can irritate the gut, and that people can develop intolerances to. If you have currently an inflamed gut, you may want to cut out caffeine, plus things like gluten and lactose. I write about it in , because there’s a difference between having a healthy gut and an unhealthy gut.
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Annie asks: How much kombucha, kimchi should you have?
I don’t have an answer for that, but I have started eating these fermented foods very recently and I must admit I thoroughly enjoy them. I don’t consume huge amounts, but my wife Dr Clare Bailey, who’s a GP, is very enthusiastic about them. She has at least one fermented food on the go all the time. We know there are billions of healthy microbes in every gram of these fermented foods. We also know that populations like the Japanese and South Koreans who consume them have very decent life expectancies. So I can’t put a finger on it, but I would suggest you give it a go. Though, if you’re not used to these, I would start gradually, because you don’t want to overload your gut with a lot of strangers. Rather like bringing strangers into your house – bring them in a few at a time and let it build up.
Is too much coffee bad?
Too much of anything is generally bad. Certainly more than four or five cups a day and the benefits begin to wear off.
Anna asks: Does taking pre-biotics help?
Yes. A probiotic is living bacteria which you’ll find in fermented food or in yogurt or something like that, or you might take in capsule form. A pre-biotic is really the foods that fertilise your gut and are good for the good bacteria down there. These are typically fibre, things like inulin, things like resistant starch. I write about it extensively because that’s where the real goodness comes from. The Mediterranean diet is very rich in the foods which are shown to be very good forms of pre-biotic. They’re good for you, but they’re also good for what I call “the old friends” in the gut. These are the kind of microbes that have evolved with us and are essential for our health.
Lily: Does taking probiotics help?
It depends. There are a lot of things marketed as probiotics and I think the evidence there effectively is very, very limited. If you’re in decent health at the moment then I don’t think taking a probiotic is going to help at all. If, however, you have hay fever, if you are currently taking antibiotics, or if you have something like travellers’ diarrhoea, then there are specific types of probiotic which are helpful. A probiotic which is good for diarrhoea is not going to help you with something like hay fever or indeed arthritis.
In my book I point you at a run by the American government, which lists some very decent evidence, or you can kind of visit my website, which is , and again that provides links. As I said, this is a really interesting but emerging field of science. There’s a lot of good stuff emerging, but there’s also a lot of rubbish as well.
Ian: How does bacteria survive stomach acids?
That’s a good question. The thing is, if you have fermented foods, then what you’re essentially doing is chopping up vegetables, immersing them in a brine (which basically means water with salt), and then they start producing acids. So they’re quite acidic – vinegar is acidic, most of these foods are acidic. They’ve grown in an acidic environment. That means they’re much more likely than most other forms of bacteria to survive the journey through the acid pools in the stomach, through the gastric juices and to your colon intact. They are specially bred, if you like. There are certain bacteria which seem to be much more resistant to acid than others, and fortunately, these bacteria tend to be amongst the really good ones.
Lauren: is there a link between type 2 diabetes and stomach health?
Interesting question, and the answer is yes. It’s becoming very clear that people who have type 2 diabetes tend to have a different sort of microbiome than those who don’t. We also know that some mixtures of microbes are much more likely to produce inflammation than others, and there is a particular mix which seems to be associated with increased risk of obesity and type 2 diabetes.
Interestingly enough, there’s an Israeli group who did a study on mice. What they did is they effectively jet lagged the mice, and their blood sugar levels soared. And then they took poo samples from these mice and they put them in other mice and the other mice also experienced problems with their blood sugar control. It seems that you can transplant if you like almost a sort of type 2 diabetes biome from one mouse to another.
Caroline: Is a low carb, high protein, high fat diet bad for your gut?
A Mediterranean diet is good for the gut, one which is topped up with elements of Indian and Japanese cuisine, in particular fermented foods. A Mediterranean diet is not pizza and pasta. Essentially it’s quite high fat because it has lots of olive oil and oily nuts, it’s relatively low carb because it doesn’t have a lot of the pasta, but what it does have is a lot of vegetables. Vegetables contain carbohydrates, so it’s about eating the “good carbs” if you like. It’s probably sort of medium range when it comes to protein, because it’s not big on meat, but it does have decent amounts of oily fish.
I’m not a fan of high protein diets because I think the effects are temporary, and they are potentially dangerous. There’s certainly some very interesting research out of California and also out of Sydney that suggests that being on a high protein diet particularly after the age of 40 is more likely to do you damage than do you good. That said, I’m a fan of oily fish, salmon and things like that.
How much does stress affect your gut?
That’s a good question, and the answer is a lot. We have this tight link between the brain and the gut, it’s called the Vagus nerve and it’s a super high way of information. So when you get stressed your gut tightens up, you feel the pain in your gut. But ditto, if you have pain in your gut it goes to your brain, there’s a very close relationship between the two.
I am a big fan (and I write about it in the Clever Guts book) of mindfulness. Mindfulness has become incredibly trendy – I took it up about three years ago – and it’s one of the best ways of calming things down. I think if you’re going to lead a healthy lifestyle, it needs four elements. You need to eat well, you need to do a decent amount of exercise (exercise also affects the biome), you need to destress – mindfulness is a good way to do that – and you also need to sleep well, cause a good night’s sleep is hugely important. If you can get those four things going, it’s kind of like legs on a chair. Just doing one isn’t going to be enough, you need all four.
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Jean: Is gut health hereditary?
Yes, in a curious sort of way. It’s partly your genes that’ll determine the environment in which the microbes will grow – it’s a bit like a garden. Depending on whether it’s full of soil or whether it’s chalky you’ll get different microbes growing there. But also you literally inherit it from your mum, because when you’re a baby in the womb there’re virtually no microbes in the gut. As you come down the birth canal, you swallow a lot of vaginal secretions and ultimately quite a lot of your mums poo. That seeds the gut bacteria and will shape how your gut turns out.
Your mum’s breast milk as well will provide you with a lot of healthy bacteria and the really essential nutrients which will encourage the growth of good bacteria. So if you’re born by caesarian section and your mother didn’t breast feed you, you’re at significantly greater risk of all sorts of food intolerances and allergies because you won’t have quite the same healthy mix of microbes. That said, you can always improve the quality of your gut by eating properly and doing other things.
How do you monitor the gut health in children?
Interesting. If you’re super keen, obviously you can take a look at their poo that comes out. You can probably tell just by eyeballing the stuff whether it’s solid, well formed. There is – believe it or not – a scale by which you can measure it from 1-4.
It depends on whether your kid is complaining of gut pain, but broadly speaking I would encourage you to feed them with a range of foods, because what we know now is that your gut microbes, they actually tell your immune system how to behave – it’s a bit like granny bringing up the kids. They in turn are dictated by the foods you eat when you’re young. For example, if you’re at risk of peanut allergy and you have lots of peanuts when you’re young, that means you’re much less likely to develop a peanut allergy later in life. The same seems to be true of lots of other foods. So it is a really, really bad idea to constrain your kid’s diet when they’re young, with, say a paleo diet, or frankly a vegan diet. I think you have a moral choice when you’re older, but I think it’s foolish when you’re younger. You want to expose them to a wide range of foods because then you will get a wide range of gut bacteria and they in turn will tell your immune system how to behave. And that is critical.
The biome largely gets formed in the first three years of life, and although it can change later on, it can also dictate which foods, what intolerances what allergies you develop later.
Adriana: Is there a link between migraines and gut health?
The honest answer is I do not know, but I will look into it. The migraine is vasodilation, when you get an expansion of the blood vessels in your brain. Interestingly enough, there was some research that came out recently that showed that in some people they get a weakening of the blood vessels which can lead to stroke. It’s not a migraine, but again it’s the blood vessels. They discovered there’s a particular bacteria that some people have which sends signals up to the brain and causes weakening of the arteries. If you don’t have the gut bacteria, it can block the signals. Then you can stop people developing this weakness and it may well prevent them getting strokes.
I suspect that there will be something in it, but I can’t cross my heart and say I have any idea at this point in time. I would be really interested if anybody who has migraines, if they have a go at Mediterranean-style diet, have a go at fermented foods, and see if that helps at all. Do contact me on cleverguts.com. This stuff is hugely interesting, it’s exciting, it’s emerging.
I also want to do a little trial there on the effects of fibre on sleep. Because there’s some really interesting new research showing a high fibre diet means you’re going to sleep better. So I’m setting up a little trial on my website to encourage people to try this particular supplement – does it work? Doesn’t it work? I’d love to know.
Bella: Can you rehabilitate your gut? How long does it take?
Short answer seems to be yes. If you currently have gut problems – if you have an inflamed gut – then you probably wouldn’t be well advised to eat too much fibre. For me, I can quite happily eat green veggies, but if you have problems with your gut at the moment (say IBS), you may well find these things inflame it or produce gas.
For people who currently have problems with their gut I would recommend first of all that they talk to their doctor or their dietician, but secondly that they try an elimination diet where you remove a few things from your diet for a short period of time and see whether that calms things down. The classic things you might remove would include alcohol, perhaps things containing gluten, perhaps some lactose and in some cases, eggs. you have to remove it for four or five weeks, and then you can start re-introducing these foods along with fermented foods and more fibrous foods.
There are people who need their guts boosted or who might just benefit from that diet, and then there’s quite a big group of people who have things like IBS, and they need to calm things down before they start thinking about adding more of this fibrous stuff as that can lead to further complications. The gut is a complex story but a hugely, hugely interesting one.
Catherine: How do antibiotics affect your gut health?
Clearly antibiotics can be absolutely life-saving. When I was a child I lived in India and I apparently got a horrible gut infection and apparently my life was saved by antibiotics so i am hugely grateful. On the other hand, antibiotics basically wipe out everything. The broad spectrum antibiotics wipe out the good stuff and the bad stuff. It’s a bit like going into Iraq and carpeting bombing the place. You think you’re wiping out all the bad guys but effectively you’re also getting rid of people who might’ve held back the terrorists or whatever. It’s not a great strategy.
Clearly if you have to have it, you have to have it. But I would minimise (if you can) the unnecessary use of antibiotics. In young kids in particular, there is a movement now saying you might be well advised to take probiotics. But as I said there are specific probiotics that seem to be effective if you’re also taking antibiotics, but the majority of probiotics are not going to have any affect at all, so have a look at the book, have a look at the website because you need the best science and I honestly believe these are the best science that we currently have.
Did you miss Dr Michael Mosley in the special Insight episode, Gut Feeling? Watch it here or on .
