Prof Tim Spector: How Food is Affecting Your Mental Health | GREAT MOMENTS

Summary

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Podcast Summary

Podcast: Great Company with Jamie Laing
Episode: Prof Tim Spector: How Food is Affecting Your Mental Health | GREAT MOMENTS
Date: February 16, 2026
Host: Jamie Laing
Guest: Prof. Tim Spector (Co-Founder of Zoe, Professor of Epidemiology, gut health expert)

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Episode Overview

This episode of Great Company features Professor Tim Spector, a leading authority on nutrition and gut health. Jamie Laing and Prof. Spector dive deep into the groundbreaking connection between our diet, gut microbiome, and mental health, challenging long-held beliefs and underlining the importance of “feeding your gut to feed your mind.” The discussion covers scientific evidence, practical advice, and evolutionary perspectives, making a compelling case for diet as a foundational pillar of good mental health.

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Key Discussion Points and Insights

The Gut-Brain Connection

• “What we’re putting in our bodies affects our brain.” (Jamie Laing, 04:04)
• Prof. Spector confirms the robust scientific evidence linking gut health and mental well-being, despite skepticism from some traditional scientists.
  • “There’s no doubt there are very clear gut-brain interactions... The number of studies of probiotics against dummy placebos showing you can improve depression in patients.” (Tim Spector, 04:26)
  • Studies show dietary changes can improve symptoms of depression and anxiety, sometimes as effectively as medication. (04:26–06:00)
• Mouse studies demonstrate that gut bacteria can transfer anxiety:
  • “You can generate anxiety in some mice, take their poo samples, put them into other sterile mice, and those sterile mice become anxious… so in a way, anxiety and depression are partly infectious.” (Tim Spector, 05:28)
• Microbes are described as “chemical factories,” producing neurotransmitters like serotonin and GABA that directly affect mood and stress:
  • “If your microbes are stimulated in a way… it’s like a soup of all these chemicals… Those chemicals are going to reach the brain… and have an effect.” (Tim Spector, 06:04)

Understanding Neurotransmitters

• Serotonin and GABA are critical neurotransmitters, with direct links to mood and anxiety:
  • “GABA is a key one for stress responses... the fact that our microbes are producing these is clear evidence of this brain-gut connection.” (Tim Spector, 07:10)
  • Serotonin impacts happiness; deficiencies can lead to depression. The gut produces or influences a large proportion of these chemicals. (07:10–08:20)
  • “Nearly everyone, if you test someone with depression or anxiety, you’d have abnormal gut microbes on testing.” (Tim Spector, 08:40)
• The concept of the “second brain”: The gut has the second largest set of nerve cells in the body, constantly communicating with the brain. (08:25)
  • “We realize that most of the nerve cells—the second biggest set of nerve cells—are in our gut. So our microbes are always talking to nerve cells. It's called our second brain.” (Tim Spector, 08:25)

Dietary Advice for Mental Health

• Diet as First-Line Mental Health Intervention:

  • “One of the most important things everyone should do if their mood is low is start to think about their diet.” (Tim Spector, 11:41)

• Doctors don’t routinely discuss diet for mental health, so self-advocacy is key:

  • “Sadly, when you go and see your GP, they're not likely to do that. So this is why you have to do this yourself.” (Tim Spector, 10:52)

• It’s especially hard for those with depression or anxiety to care about food, so support from others is crucial. (10:52)

• Evidence shows that antidepressant effectiveness is impaired if the gut microbiome is dysfunctional:

  • “A third of them [antidepressants] don’t work at all because you have the wrong gut microbes inside you. The microbes are actually breaking down the antidepressant chemicals.” (Tim Spector, 11:01)

• Immediate Effects:

  • In the Zoe personalized nutrition program, improved mood and energy are often the first reported benefits—before physical changes or improvements in gut health markers.
    • “Mood and energy were the first things they noticed and quite big significant changes.” (Tim Spector, 12:30)
  • “The most dramatic effects are on the brain rather than, you know, the rest of the body.” (13:43)
  • The "Daily 30" (32 different high-fiber plants) can directly benefit mental well-being before other health parameters change.

• Medicine and nutrition must be seen holistically; separation between brain and body leads to missed opportunities for effective mental health interventions. (13:40)

Evolutionary Perspective on Depression and Anxiety

• Depression and anxiety are likely evolutionary protective mechanisms, not just disorders:
  • “Depression is a protective mechanism, says ‘leave me alone’... My body thinks it's under attack... I’m going to go under the duvet and stay there for a couple of weeks.” (Tim Spector, 14:50)
  • Mental distress likely served a survival function but may be poorly adapted to modern life. (15:52)
  • The body/brain can now respond “wrongly” because our environment and habits have changed so much from ancient times.

Actionable Takeaways

• If experiencing low mood, anxiety, or depression, start by revisiting dietary habits:
  • “First thing to try—the safest thing to try—is to overhaul your diet and keep your gut microbes happy.” (Tim Spector, 14:10)
• Understand that mood shifts can appear before weight loss or noticeable gut health changes.
• Raise awareness and support those around you struggling with mental health; encourage dietary improvements as part of self-care.

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Notable Quotes & Memorable Moments

• “You can generate anxiety in some mice, take their poo samples, put them into other sterile mice, and those sterile mice become anxious… so in a way, anxiety and depression are partly infectious.”
  — Prof. Tim Spector (05:28)
• “GABA is a key one for stress responses... the fact that our microbes are producing these is clear evidence of this brain-gut connection.”
  — Prof. Tim Spector (07:10)
• “Nearly everyone, if you test someone with depression or anxiety, you’d have abnormal gut microbes on testing.”
  — Prof. Tim Spector (08:40)
• “Sadly, when you go and see your GP, they're not likely to do that. So this is why you have to do this yourself.”
  — Prof. Tim Spector (10:52)
• “First thing to try—the safest thing to try—is to overhaul your diet and keep your gut microbes happy.”
  — Prof. Tim Spector (14:10)

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Timestamps for Key Segments

• [04:04] – Introduction to the gut-brain connection and scientific skepticism
• [05:28] – Mouse studies: how gut microbes can transfer anxiety
• [07:04-08:25] – Explanation of serotonin, GABA, and “second brain”
• [10:32] – Advice for the new year: start with changing your diet for mental health
• [11:01] – How gut microbes influence antidepressant effectiveness
• [12:30] – Zoe study findings: mood and energy often improve first
• [13:40] – The need for holistic medicine: connecting brain and gut
• [14:49] – Evolutionary role of depression and anxiety

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Conclusion

Jamie and Prof. Tim Spector deliver a compelling message: food isn’t just about physical health, but vital to mental well-being. The conversation is practical, optimistic, and evidence-driven, empowering listeners to take control of their mental health through simple changes in daily nutrition. If you’re feeling low, anxious, or struggling with mood, Prof. Spector’s advice is clear—start by feeding your gut, and your mind will often follow.

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For more insights, check the full episode linked in the show notes.

Transcript

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Did I talk too much? Can't I just let it go? I was thinking so much.

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Take a breath.

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[Jamie Lang]

Hello everyone, I'm Jamie Lang and this is great moments. Hey guys, welcome back. Now today's great moment is with Professor Tim Spector who I can now call a friend. Okay. He's the founder of Zoe, the health app and is one of kind of the most fascinating scientists out there. Now on this podcast, I love speaking to a variety of different people and I love speaking to experts. And Tim didn't disappoint. He completely, and I'm being honest with you, he completely changed the way I think about food and inspired me to eat better. So trust me, this is going to blow your mind. Okay, so here we go. Enjoy this great moment with Professor Tim Spector. Gut I'm fascinated with.

[Professor Tim Spector]

Right.

[Jamie Lang]

And I think this is one of the big things, like you said that recently, people are obsessed with because what we're putting in our bodies affects our brain. However, you do have people who don't believe that still and they think that there is no correlation between the gut and our brain and the decline of mental health. Can you talk to me about that and the sort of data that surrounds it?

[BetterHelp Representative / Sarah from Olive and June]

Yes.

[Professor Tim Spector]

Well, I think everyone believes there's a connection, but there'd be other scientists that said it's rather trivial and hasn't been proven yet. Whereas, you know, and these are people who are perhaps embedded in more solid areas of science like genetics. So, well, you can explain it all. People are generally distrustful in science of new areas that they haven't been trained in. And initial thing is you just say that's a fad or that's driven by commercial interests. So you're creating something just in order to sell some probiotics or something. But there's no doubt there are very clear gut brain interactions. The number of studies of probiotics against dummy placebos showing you can improve depression in patients. There are other studies showing just by improving diet of Mild to moderate depressives, you can improve their symptoms to the same extent as antidepressants. And they've done lots of careful mouse studies where you can actually generate anxiety in some mice. Take their poo samples, put them into other sterile mice, and those sterile mice become anxious. Get out of here. So in a way, yeah, anxiety and, and, and depression, you know, are partly infectious. What if you think about it in a different way, but which, which sort of. Which a bit mind blowing, but if you start thinking about what microbes do, they're basically chemical factories. They produce chemicals, thousands of chemicals. Some of them affect the brain, like serotonin or there's one called gaba, which is affected when you take Valium, for example, and then probably many others that also affect the brain. And so if your microbes are stimulated in a way in your stool sample, it's like a soup of all these chemicals. You're putting them into someone else there. Those chemicals are going to reach the brain of that person or that mouse and have an effect. So it does sort of make sense once you break down this idea of difference between, you know, poo and food and things, and just think of everything as chemicals.

[Jamie Lang]

For anyone who doesn't know, can you explain what serotonin is and what GABA is? Just very briefly?

[Professor Tim Spector]

They're both neurotransmitters, which means that they're produced in the body, going in the blood, and they will have an effect on the brain in that there are receptors in the brain for these things. So your brain will react to them. GABA is a key one for stress responses, so that when you're taking a Valium, benzodiazepine or a Valium, you're changing these receptors in the brain, these GABA receptors, which will just calm you down. And so the fact that our microbes are producing these is, is a clear evidence of this brain gut connection. And serotonin is part of this whole process that comes from tryptophan and serotonin and then the dopamine pathways, where we have receptors for these, these chemicals which can change our mood, which can make us feel warm and happy, or lacking it, more depressed. And they're just two examples of the many chemicals that we still don't know about that is likely our gut are producing. And we know, for example, that nearly everyone, if you test someone with depression or anxiety, you'd have abnormal gut microbes. On testing, when we sequence them, doing something like the Zoe test, we'd see far more unhealthy microbes than healthy Ones and the. We realize that most of the nerve cells, the second biggest set of nerve cells are in our gut. So our microbes are always talking to nerve cells. And it's called our second brain is in our guts. So every time, you know, before an exam or stress, you know, you're getting signals from your gut that you know, are actually transmitted that should be in your brain, right? You're saying the two are really highly conn. Is why we get gut feelings and butterflies in our stomach and all these other things because the two systems are highly connected. They're always talking to each other and therefore this just tells us much more that in order to help our brain, we really need to get our gut microbes in order, in order to get our gut microbes in order producing the right chemicals, we need to feed them. Right? And this, this connect, this three way connection is, is really, really important. And a lot of our current mental health issues, and there's an epidemic of them at the moment, are due to the fact that we have abnormal gut microbes producing the wrong chemicals. And our brain misinterpreting these signals and thinking that, you know, we're actually than we really are. And this is this, this strange loop that we're probably in at the moment.

[Jamie Lang]

This is the beginning of the year 2025. So people are listening to it and they are in their sort of zone at the moment where they're thinking, right, New Year, New Me. And perhaps they are depressed, perhaps they're anxious, perhaps they're feeling low mood and they're not feeling great. You would say to that individual who's listening, first place is look at your diet and try and change that.

[Professor Tim Spector]

Absolutely, yes, 100% yes. You know, but sadly, when you go and see your gp, they're not likely to do that. So this is why you have to do this yourself. And it's particularly hard because if you are in that depressed or anxious state, often your brain switches off interest in food and you just really see it as fuel. So it's really important for also people around you or in your family to actually help someone who is in that state to eat better. And there's even evidence that if you have more severe depression and you go on antidepressants, a third of them, third of them don't work at all because you have the wrong gut microbes inside you. So they're just never going to work. The microbes are actually breaking down the antidepressant chemicals and so they don't work. They're inactivating them so again, really clear links between mental health, also the medications and food. But one of the most important things everyone should do if their mood is low is start to think about their diet. And this is something I wasn't really aware of until really fully, until about a couple of years ago, how important it was when we first started putting people on, seeing what happened to people on the Zoe program. This is this personalized nutrition program and they get, you know, much a gut friendly diet, avoid sugar spikes, fat spikes, et cetera. One of the first things people noticed and reported back to us when they followed the plan was their mood and energy improved. So way before anything else, you know, before they noticed even change in constipation or weight or even before their gut microbes, we could see a change. Mood and energy were the first things they noticed and quite big significant changes. And this, we've seen this throughout our studies as how even people shifting their whole diet or even taking. We've got a mixture called the daily 30, which is a high fiber prebiotic of 32 plants. We gave that in a randomized trial. And again, the most dramatic effects are on the brain rather than, you know, the rest of the body. So everything's telling us how crucial this, this link is between the gut and the brain. And I don't, I think it's been totally underestimated. And of course, you know, because we have this division in, in medicine between the brain and the body, psychiatrists generally who deal with depression haven't had any interest in the gut or in nutrition. And you know, we need to, we need to treat this, all the bits of the body in the same way and have a much more holistic approach and not see this as, oh, that's brain disease, that's, that's someone else's domain. It's all, it's all absolutely linked up. So anyone listening to this? Absolutely. If you've got any mood, energy problems, feeling a bit low, you know, those blues, then you know, first thing to try, the safest thing to try is to, you know, overhaul your diet and keep your gut microbes happy.

[Jamie Lang]

That's so interesting because if you, if you're not as sort of driven by sort of challenging the status quo, right, like yourself, and you go to the doctor and they say, well, you're depressed. You then label yourself as depressed or anxious and you go, well, I'm just depressed and anxious. And then you just say, well, that's what I am, rather than going, oh, hang on a second, maybe it's because I'm eating Junk food or I'm eating something wrong or something else. Is there?

[Professor Tim Spector]

Absolutely, yes.

[Jamie Lang]

And I mean, you're treating the wrong thing.

[Professor Tim Spector]

And anyone with, with gut problems knows that, you know, their mood is, is really low. And it's not just the physical side of it. There's something else going on that's sending signals to the brain to say, you know, I'm sick, go into depressed mode. Which, you know, we think is a sort of protective mechanism. Evolution has given, you know, depression is a protective mechanism, says leave me alone, you know, you know, my body thinks it's under attack. You know, I'm just going to go into under the duvet and stay there for a couple of weeks. So that's the sort of theory about why, you know, humans have depression, which has a mod, you know, some genetic basis as well.

[Jamie Lang]

It's an evolution thing. Same with anxiety, because you think your, your body thinks it's under attack. So it's the flight of the fight or flight where you, you either fight it or you run because the saber toothed tiger is coming around the corner.

[Professor Tim Spector]

Yeah, there has to be some advantage in some scenarios of it existing. Otherwise it would have, you know, depression wouldn't be around because it would have been outbred. Because if you're, you know, depressed, male or female, and you'd spend all your time under the duvet, you're not likely to be running around, you know, having babies and keeping the jeans going, you know, no one would find you. So clearly there had to be some survival advantage to outweigh the fact that you weren't the life and soul of the party. And it's that balance that is interesting. But I think in the modern era it's obviously quite different. Our genes were designed for a different time. And so we have to get involved in that and realize that, you know, our brain sometimes gets it wrong.

[Jamie Lang]

Okay, did that blow your mind? Well, I really hope you enjoyed that episode with Tim Inspector. I mean, fascinating. I mean the link between what we eat and our mental health. I mean, sometimes we forget so much that actually what we're putting in our body will also affect our brain. And I promise you, the more that I started eat to eat healthier, the better my clarity. Less brain fog, the better I feel about myself. Okay. Also, the changes in your diet can decrease levels of anxiety and depression. That's mad. So if you're feeling anxious, maybe you're feeling a little low, try changing your diet as well as all the other things you can do. Now if you like that you need to check out Tim's full episode. Okay. He has so many amazing insights. We're going to leave a link in the show notes. Just go and click on it. It'll take you to the full episode. Tim is just one of the many amazing guests we've had on Great Company. So if you haven't already, make sure you check out some of the others too. And don't forget to follow and subscribe. And we'll be back next week for a brand new episode of Great.

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