Could depression, dementia, and poor oral health all have one uniting link? The gut microbiome contains 200 more genes than human cells, and research shows its strong impact on mental illness, brain health, and chronic inflammation.
Professor of epidemiology at King’s College London Tim Spector breaks down the science of how gut microbes produce the chemicals that shape your mood, your immune system, and your cognitive health, and why the standard Western diet has been systematically destroying them for 50 years.
About the speaker: Tim Spector is a Professor of Epidemiology at King’s College London, director of the Twins UK study, scientific co-founder at ZOE, and one of the world’s most-cited scientists. He's also the author of the bestsellers, Spoon-Fed, The Diet Myth, Food for Life, and Ferment.
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Timestamps
00:00:33 Chapter 1: How the gut microbiome works
00:07:18 A sick gut = a sick brain
00:15:20 Why modern life is inflaming you
00:17:17 Chapter 2: An unhealthy gut leads to an unhealthy brain
00:20:44 Bad gut health is linked to dementia
00:25:58 What your teeth reveal about your inflammation levels
00:29:47 Chapter 3: 8 tips for maintaining a healthy gut ecosystem
00:33:18 Eat 30 plants a week (here’s how)
00:41:48 The ultra-processed food trap
00:46:21 Eat the rainbow, fast overnight
00:54:47 Chapter 4: Why the internet gets dieting all wrong
00:58:45 Why fad diets always fail long-term
01:01:02 Organic, salt, fish — what actually matters
01:07:53 Supplements won’t save you
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Transcript
Below is a transcript of the first five minutes of this video interview. This is a true verbatim transcript that captures the conversation exactly as it happened. If you’d like to read the full transcript while following along with the video, click here.
My name’s Tim Spector, I’m an MD, I’m a professor of epidemiology at King’s College in London, and I’m also co-founder of the nutrition and gut health company, ZOE. Today on Big Think, I’m going to talk about the connection between what’s going on in your gut, your gut microbes, and how that affects your brain and your mental health. I’ll also be giving you tips about how you can improve your gut health to improve your overall health.
Chapter 1: How the gut microbiome works
The gut microbiome, I like to think of as like a virtual organ in our bodies that we’ve only recently discovered. Something like discovering we had a liver. And essentially it’s made up of trillions of little tiny microbes that you need a microscope to see, bacteria, fungi, parasites, viruses, and other things we still don’t exactly know about. This collection forms a community mainly inside the lower part of our colon, the large intestine. They essentially need to be thought of as mini pharmacies. They convert the food that we eat into chemicals, into hundreds and thousands of different chemicals, and those chemicals have this amazing impact on our body that we’re only just beginning to realize. This collection of microbes has something like 200 times more genes than we have in our own human cells. That means they’re much more versatile, they’re more flexible in what they can produce in terms of chemicals, and they’re actually more numerous than our human cells.
This is important because we evolved from these bacteria and the very first mammals and then humans were built because they contained these colonies of microbes that could interact with them. And without these microbes, we really wouldn’t function, and particularly our brains don’t develop normally.
So one way to think about our gut microbiome is either as the environment of a jungle or an amazing natural zoo where you’ve got these thousands of different species of microbes that have taken over a little niche inside our gut that is very specialized to them. They’re not all fighting for the same food, they’ve evolved just like animals have to have very specific tastes. The example I like comes from our own research where we found there is one bug that only really eats or drinks coffee. It is so fussy, it hangs around maybe for years just waiting for that first cup of coffee before it will replicate and really start to be noticeable. If we start thinking of coffee as a great example, then you think about all the other bugs that we might have lying dormant in our guts that are waiting for us to eat something unusual, say a bit of baobab or some beetroot or some particular type of nut or herb or spice.
And so that’s a really important concept because we now know that the more diverse your gut microbes are, the healthier you are. So that’s why we need to be thinking, how can I best feed these very different gut microbes, some of which might like coffee, others will only like the leaf of a bit of cabbage, others might like seeds or nuts, and others will like the leftovers from what the other microbes have eaten. And this is also a really interesting concept because they’re working together. They make sure there’s no waste. They are these perfect ecological beings so that the concept of waste doesn’t really exist.
What they’ve shown in some mouse studies is that if you have a really strong colony of gut microbes that are very diverse, then you eat your standard diet, you have no waste left over. But if you only have a few microbes, rather poor colony. They’re not very well diversified. You get leftovers. And when you get the leftovers, then you get what we call the bad bugs. We’ll eat those because they’ve got something to eat. So a really good, healthy colony of microbes like a zoo is one where all the animals have a role. They’ve got something to eat. There’s no real waste and everything is used up. It’s really a marvelous model that we all love, a sustainable gut society.
Although we all have thousands of species of these trillions of bugs inside our guts, we’re actually really very different one to another. And this is because as kids, when we’re born, we’re born sterile. So it’s slightly random which microbes end up colonizing our own colons. And it turns out that the average person only shares about 20% of their gut microbes with another. And even in identical twins, they don’t share many more than that. So it’s a process that’s part random, part designed that way, and not very genetic.
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