Can fermented food fight inflammation? With Tim Spector

Are fermented foods the missing link in our health, or just the latest wellness trend? 

In this episode, Professor Tim Spector, a world-leading scientist in gut health and co-founder of ZOE, challenges what we think we know about yogurt, cheese, kombucha, and more.

Tim uncovers why milk and cheese aren’t the same in your body — and the surprising science showing cheese might not be the villain it was once made out to be.

He also shares emerging evidence that fermented foods could influence inflammation, immunity, metabolism, and even mood, often in a matter of weeks.

Tim breaks down the easiest ways to actually eat more fermented foods without overhauling your life. By the end, you’ll be questioning what’s in your fridge - and wondering if one tiny daily habit could do far more than you’d ever expect.

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Transcript

Jonathan Wolf: Tim, what a pleasure. Thank you for joining me today.

Tim Spector: Great to be here.

Jonathan Wolf: So you know the rules. We're gonna start with a rapid-fire Q&A from our listeners. Are you ready to go?

Tim Spector: Hit me.

Jonathan Wolf: Can fermented food support better mental health?

Tim Spector: Absolutely.

Jonathan Wolf: Is fermenting food at home dangerous?

Tim Spector: No, but depends on your spouse.

Jonathan Wolf: You're throwing me off track already. Does fermented food always have a really strong flavor?

Tim Spector: No, it doesn't.

Jonathan Wolf: Can dead microbes benefit your health?

Tim Spector: They can.

Jonathan Wolf: Is your wife perpetually annoyed by the state of your fridge?

Tim Spector: Yes. Despite all the things I do.

Jonathan Wolf: I know her and you, so I think she might say something similar. What's the biggest misconception about fermented foods?

Tim Spector: Probably that they're always smelly and dangerous and it's highly risky to eat them. And that's not true. It's not true.

Jonathan Wolf: So Tim, I think that's a brilliant introduction, and I know you've got a lot to say about the process of fermenting and the wonders of fermented food. After all, you literally just wrote the book on it. So let's just start at the beginning. What is fermenting?

Tim Spector: Fermenting is the process by which microbes transform food into something better. And by better I mean something that preserves it longer before it goes moldy. It also transforms into something that tastes better and and more complex, and it also transforms into something that is healthier for you than the original. 

If you look at milk, it's not particularly good for as an adult, but if you ferment it, it has all these extra properties that are good for you. If you take grapes and you ferment them, you get wine, which has incredible complexities of taste and many other properties and smells. 

And so generally, you're just increasing the amount of chemicals and benefits of those foods by the power of the microbes.

Jonathan Wolf: And could you maybe help us understand a bit more what's going on? So you gave that example of milk and it turns into something else, right? Like cheese or something.

Tim Spector: Yeah. And I think people do get confused about the difference between fermenting and going moldy because there's sort of similar processes involving bugs microbes. And by those, we're mainly talking about bacteria and we're talking about yeast. 

So if you leave some milk out for a couple of weeks, you go on holiday, it comes back. It'll be moldy. It'll be off because randomly microbes are coming from the air around it or in the container, and they're starting to eat away at the milk using it to reproduce. And then they'll produce funny chemicals and smells, and it's rather random, which microbes land on it, so you're not in control of that process. 

So you'll get a molds eventually growing on it as the acidity and everything changes in that product, so it becomes completely inedible.

Jonathan Wolf: Okay. So that's not the same as fermentation.

Tim Spector: It's not the same as fermentation. So fermentation is where you are tightly controlling the conditions around that milk, and you are making sure that only the microbes that you want to grow in the milk are growing in the milk. So that's what happens. 

For example, when you make yogurt, you are heating the milk up. Then you're bringing it down to a certain temperature in a very close range where only certain microbes that you want to favor will grow and others are killed off. And so if you get the microbes that you want really propagating in that food, they elbow all the other ones out the way. 

So by changing the temperature, that allows certain microbes to grow. And in the case of yogurt, they then produce acid. Lactic acid and acetic acid that will lower the pH. That increases the acidity and that again stops other microbes creeping in and taking over. 

So you are selecting a really small percentage of all the microbes that could be in that food into this narrow range. It's a bit like farming or precision gardening. You want just these microbes that live in these particular conditions to flourish. And when they do that, they make sure nothing else can get in there. 

So once you've got the acidity, the pH is below 4.5, nothing nasty can grow. Okay? So that's really important, which doesn't happen if you just leave food out. That's essentially what the difference is. One is a highly tuned cultivation, and the other is a random collection of microbes.

Jonathan Wolf: So now help us to understand what actually happens to the food. So, you were talking about milk as an example. Why do we want microbes to eat the milk rather than us eat it directly? What happens as a result of this?

Tim Spector: So it's the same process that happens inside your body when you eat any food. Microbes will digest it and break it down into chemicals and break it down into all the nutrients and, and recycle them and use them and produce many other byproduct chemicals in exchange. 

So that's where most of our body gets its chemicals from, is from our microbes working overtime on the food. And what happens outside is you're getting a little snapshot of what's happening in your body when you do your own fermentation, say, and the microbes will be breaking down the milk. They produce substances like acids, which further change the properties of that milk and they can turn it into yogurt or they can turn it into cheese and the extra chemicals they produce also provide differences in flavors. 

So chemicals are essentially complex flavors. So some of them will float in the air and you'll be able to smell them. Others, you pick them up on your tongue and making something boring into something incredibly interesting because you're getting all these extra chemicals. 

The complexity of breaking down the original product just milk, just this sugar lactose. It's broken into all these different things so that something like cheese becomes this really complex food product from something really basic, just from microbes working hard at it to produce lots of different substances, which then is this more complicated approach. 

And again, the same thing. Think grapes and wine. Why does wine taste so much better, more interesting than just sweet or sour grapes? It's, it's all these extra chemicals that are providing us with that. And in those chemicals, there are nutrients, there's vitamins, things that we can't necessarily pick up ourselves that make it healthier.

Jonathan Wolf: I'm thinking about analogy as you're describing this. So I was actually discussing with my little girl this morning as we're going to school, talking about plants and how they're producing the oxygen that she needs and that all they need is basically water and sunlight and then they make all of these complex fruit and leaves and all the rest of it. 

And is that an analogy here, which is almost like in this case you're saying the milk is a very simple sugar. And then these bacteria in this fermented process is suddenly making this incredibly complex arrangement of different molecules. A bit like the plant taking just the sunlight and the carbon dioxide and suddenly managing to make a raspberry bush.

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Tim Spector: Exactly. The little sort of chemical factories. So you just got to feed them some of the key essentials. And they're all specialized in different ways. They will produce different byproduct chemicals that by working as a team, they can create something far more complicated, something far more interesting than the starting product. 

And that's why they are so helpful to us, and that's why it's a great analogy and why everyone really needs to know about fermenting because it's sort of what's happening inside your own body. Every time you're eating food, your microbes have the chance to make that food much more nutritious and useful for your body. 

If you've got the right microbes, if you've got the right team working there, they can create all the chemicals and vitamins and things that you need for the rest of your body. Essentially, when we're having fermented foods, we're, it's double fermented, so it's fermented outside and that's why we, we, we've evolved to actually like fermented foods because of some of these benefits. 

And then it comes when we have cheese again, for example. It's then broken down again for a second time in our bodies and we still get the benefits from it from that second wave of microbes attacking it.

Jonathan Wolf: Tim, you've talked about the way that fermentation is changing the taste and making it more complicated and taste great, which is your example of like cheese or wine versus just milk or a grape. 

But you've touched also on this certain thing about it being healthier. So it's not only about tasting better, you're saying this can actually have health benefits. Could you help us to understand why and how?

Tim Spector: We don’t know exactly, but in virtually all the cases that I've looked at. In research from my book, the fermented product is nearly always healthier than the original product, and it's probably because it contains more healthy chemicals and compounds. 

So you take cheese, for example. There's no evidence that milk has particularly great benefits to adults because it's quite two dimensional. It's got sugar, it's got protein, but when you get cheese, all the evidence suggests that regular cheese eaters have lower mortality, less heart disease risk, et cetera, which is rather strange because the initial products is the same. 

So it's probably the microbes themselves changing the chemicals in that food. So they're producing chemicals that are actually helpful for our bodies and those chemicals either acting directly on us or they're affecting the other microbes in our ecosystem to then produce healthy chemicals. So I think complexity is generally better for us. 

That seems to be the general rule. And the same is true, eating just cabbage doesn't seem to be as good as having fermented cabbage, which we call sauerkraut. Many other examples where the basic plant, just having. That plant is fine for you, but we seem to get extra benefit from perhaps the way the microbes have created all these extra chemicals and tastes and aroma. 

So the more interesting the taste and flavor, the healthier it tends to be for us. And I think that's something really interesting from evolutionary point of view about why do we seek out these slightly sour tastes rather than the bland taste. And it. Could well be that evolution has primed us. These things are actually beneficial for us.

Jonathan Wolf: You are saying that if I took milk under a microscope and could measure the different molecules inside it, it's quite simple. There's sugar and there's some protein, but there's not lots of different ones. I think when you were saying it's two dimensional, that's sort of what you're saying, and then you're saying after these microbes, these bacteria and fungus have been chomping away at it, they then produce hundreds of molecules. Thousands of molecules. Millions of molecules.

Tim Spector: Thousands of molecules, yes.

Jonathan Wolf: And so that's vastly more complicated after the fermentation. Than beforehand.

Tim Spector: And that's the whole basis of fermentation. When you think about grapes into wine or hops into beer, you're getting this incredible complexity of flavors. And whenever you get complexity of flavors, you know that underlying, that there's lots more chemicals. You're just tasting a percentage of them, but the complexity of the product has really gone up a hundred fold.

Jonathan Wolf: Now many of our listeners will be saying, why is that a good thing? I feel like I'm spending my life trying to avoid adding more chemicals into my diet. And you, you've been using this word chemicals, right? Which I think we're all trained like that sounds terrible. Why would I want more chemicals by going from milk to cheese or yogurt?

Tim Spector: Well, Jonathan, there's nothing terrible about chemicals. Okay? We exist in a chemical world, food is made up of perhaps 50 to a hundred thousand different individual chemicals, just like our bodies are made up of chemicals. 

So we are living in a chemical universe. And what we're saying is that the greater variety of chemicals there are, particularly if it's produced naturally as part of our evolution, these should be helping us survive longer and having a natural protective effect for our bodies if we are producing them. 

It's not the same as if you are eating foods created by the petrochemical industry as artificial sweeteners or something is a good example, but the ones that come from foods that we've been having from thousands of years, then I think we should be embracing that complexity, 'cause when you get foods often that are made industrially, they go down to the simplest components that are cheap. You lose that complexity and that's why they're full of sugar and salt to disguise the fact they have no depth or complexity to them. 

We should be embracing anything that has interesting flavors and what I call this depth to it, just like a good wine, a good cheese, a really good craft beer. A coffee that's got more to it than just bitterness. It isn't just these simple five tastes, there's much more to it. 

So this is what fermentation really brings to the table, and it opens our senses up more. There's some people believe that we have always been drawn to these foods because they provided microbes that we couldn't get otherwise into our diet. 

So there's a recent cool paper in nature which actually measured the overlap between microbes in food and in our guts. And it's only about 4%. So when we're having these fermented foods, most of them are not ones that are already in our gut, they're foreign to it. They prefer living in the milk or the cabbage or whatever it is.

Jonathan Wolf: And just to clarify, you are saying that when I eat the fermented food, there are. Still live microbes in the fermented food, Tim?

Tim Spector: Yes. So most fermented foods we're talking about are live ferments, and they contain probiotic microbes, by which we mean microbes that have been shown to have some health benefit. In humans, you can have fermented foods that have dead microbes, and you have most fermented foods, which are mixture of live and dead microbes.

Jonathan Wolf: So could you just help us to understand, what are the classic fermented foods that we're used to eating and when do they have live microbes in and when not?

Tim Spector: Okay, well, the classic ones would be your yogurt, which has live microbes in it. Cheese, fermented milks, which are called kefir in the US. Then you've got the krauts, which is fermented cabbage or beetroot sauerkrauts. You've got fermented tea, which is called kombucha. You've got fermented soybeans, which are called the miso products, and soy sauce and miso paste, NATO and Tempe. 

And you've got a whole range of other ones, particularly all kinds of fermented vegetables and vinegars. They're live. 

Then you've got dead ones such as beer, wine. And sourdough bread classically. You also got some other strange ones that people don't realize are fermented things like Marmite and Tabasco. So a lot of the condiments that we all eat now, were certainly originally fermented, like tomato sauce was originally an Indonesian ferment that Heinz took and made into a staple by adding 30% sugar.

Jonathan Wolf: I'm taking it that that's not a fermented food I should be adding to my diet today.

Tim Spector: No, but in my book, Jonathan, there's a really good recipe for making your own tomato ketchup, which is lovely.

Jonathan Wolf: So just to play that, there's a set of these fermented foods that still have live bacteria in, and then the ones that I guess are most famous as I think about it like a beer or a wine or bread. There's fermentation in terms of making those products, but then the bacteria ends up being dead. Could you just explain for a minute, why they end up being dead?

Tim Spector: They're usually deliberately killed. Because you don't necessarily want your, say, your beer to keep brewing after you've sold it because it produces more gas and will explode. 

So this is the problem of fermentation is, it has to stop at some point. And everyone who's ever fermented will occasionally have something explode. And I've had a few occasions where bottles have come off rather unexpectedly, and again, upset my wife. 

But this is why when you scale up fermentation, manufacturers of things like kombucha have the same problem as the beer makers. They want to stop fermentation so you can put it in cans or bottles, so it's no longer continuing to produce gas. So anything above 65 degrees will just about kill all these microbes. 

So you've got a lot of these products that have started live, ended up dead. We haven't talked about coffee and chocolate, but similar process just before roasting. They ferment the beans. And that's very much part of that complexity of why coffee and chocolate, when it's done properly, have such great, rich, interesting taste and certain tea as well.

Jonathan Wolf: So they're a bit like you're describing with the bread, the fermentation is a really important part of making the coffee or the chocolate, but the bacteria ends up being killed.

Tim Spector: Exactly. Yeah. So that provides the taste. And up until recently we thought that didn't provide any health benefit. Dead microbes. Completely useless. That's what I thought three years ago for the book. 

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I started really researching this in more detail and started seeing more and more studies suggesting that even pasteurizing some of these foods could have some effect. And the first, they didn't believe it, they just thought they'd got the experiment wrong. There's now, I guess, about 15 randomized controlled trials showing that a dead microbe fermented food works more than placebo in terms of health benefit in humans, whether it's in adults or children. 

So we know that these things now do work and in a few cases they work better than in the live version, which is really weird. There's a probiotic called akkermansia, which I think we've discussed on other podcasts that crops up a lot. The people who studied this actually worked out that it had a beneficial effect above and beyond the live version, which is very hard to work out. But they didn't believe it until they started doing placebo studies and ensure it works. So we know that live microbes now work.

Jonathan Wolf: You're sort of putting these in two categories. I think Tim and I would say you've got this first category where there's fermentation to make something that we eat, but basically the microbe ends up being dead and that is basically what I grew up with. Right. So you mentioned beer, wine, bread, coffee, chocolate. These are all things that are completely normal in the western world. And then you gave me a a list of other foods and like the yogurt and the cheese. I grew up with, but then you're like, oh, and kefir and kraut and kombucha and meat. So I didn't have any of these things growing up. 

Why is it that those have not really been that common in the UK and the US, and I would say a lot of English speaking countries. But then you're talking about these foods, which have been common in other cultures.

Tim Spector: Absolutely, yes. So if you look at the world map of fermented foods, the English speaking colonies are really the odd ones out. You only have to look in Europe and you see that Scandinavia, they've been having fermented milks and fermented fish. 

You go to the Mediterranean. They have a strong tradition of making their own cheeses and, and yogurts,and other ferments. Central and Eastern Europe fermenting vegetables like there's no tomorrow. 

Every home is packed with this stuff as well as the CFIs in Poland, et cetera. And then most of Africa actually has fermented porridge and beers and oats and grains and breads. And then you've got, of course, the Asian, the kimchi’s, the misos. The Japanese worship a certain fungus called Koji. So it's like we are the odd ones out. 

I said, how did this happen? Well, and I think it's part of this Anglo-Saxon idea of sterility is important. Industrialization. We were the first to get fridges, and when we did, we sort of threw out all those old habits that used to preserve our food before the fridge and we went into the industrial revolution first, and it was just this idea that modern, sterile is the way to go. 

And of course the US has probably led the way with getting rid of anything old fashioned. And if you can stick a chemical in it and make it last forever, rather than live ferments, we do it.

Jonathan Wolf: I think that's fascinating. You're saying that in a way we were the odd ones out and it's really, the United Kingdom and English speaking countries that really have the sort of the or the exception, and everywhere else is really used to these live fermented foods.

Tim Spector: They never gave them up essentially even when they got refrigerators, they still kept going with it. Yeah, exactly. And they didn't switch everything to using vinegars rather than salt brine. Which is the essential difference between pickling and fermenting, which is people often get confused about pickling really should refer to when you just add vinegar to it. 

And usually we're talking about commercial vinegar, which is just acetic acid rather than the vinegar you can make with microbes. It's really strange how we lost out, but it sort of makes sense. 

By the second World War, we'd closed all the little dairies doing their own fermented cheeses. 'cause we wanted for the war effort to make one cheese cheddar. And that translated to the US and this idea that, we wouldn't have these little micro communities doing their own fermenting. 

But now the last 10 years have seen a massive reversal of that. And we now have more cheeses than in France. Local cheeses. If you count them up, the little strains of cheese in the UK we can see in our supermarkets how things have changed.

10 years ago when I wrote Diet Myth and you met two people in a crowd coming to one of my talks, had heard of kimchi or kefir. Now every supermarket you go to has a range of those products. 

Just in five years, the landscape has changed massively. So I think the good thing about the English speaking countries is that although we have the worst food in the world, we have the ability to change it fast than any other culture. Because we're not locked into it. 

So I'm seeing all these exciting changes of people getting back into it and it suddenly became back into our normal behavior and culture.

Jonathan Wolf: And I understand a bit later in this episode, you're gonna show us that these live ferments aren't only something we can buy from the supermarket, but it is actually possible to do this at home.

Tim Spector: Exactly. You can do both. Yeah. Try it in the supermarket and then give it a go at home and save yourself a lot of money and have a bit of fun.

Jonathan Wolf: So before we get to the practical questions about how you add ferments to your diet and what you could do, I'd love to follow up on what you're talking about, about why is this healthy? 

When I first met you, getting on from nine years ago and we started ZOE, you didn't really talk a lot about fermented food. You talked about a lot of different things to do with nutrition. 

You talked a lot about the importance of the gut microbiome, but this is something that's really new, really in the last few years. So what's changed your mind and why do you now feel that there are health benefits?

Tim Spector: Well, 10 years ago there were lots of little studies around the world, 10 or 20 people where they'd give them some fermented food and they'd see how they got on, but they didn't stack up for me as a scientist of being really credible. 

And it's only about three years ago that for me, it really switched. And there were a couple of studies that really convinced me this was more than just, oh yeah, this sounds a good thing to have, but I'm not sure how good it is. 

One was this study from Stanford, our colleagues, Christopher Gardner, you know well, and Justin Sonenberg did a study where they had relatively small number of people, about 28 people, and they put them into two groups. 

One, having a high fiber diet. The other one having five portions of fermented food a day for around three or four weeks. And they basically taking nearly daily blood samples. So small study, but very intensive. And this hadn't been done before. 

And in the blood samples, they were looking at all the immune proteins, so a whole batch of immunological studies at, at great detail and expense. And what they showed was that even after a couple of weeks, you saw a really significant drop in inflammation markers in the fermented food group.

So not only did their microbiome change more than the high fiber group, but they had this dramatic decrease in inflammation markers. So it really helped the immune system. It changed 17 out of. 19 proteins they measured, so across the board, these were having a real effect on the immune system, and that's probably the mechanism by which they are having this health effect. 

So the Stanford study for the first time showed in great detail that fermented foods can have a dramatic impact on the immune system as well as the gut microbiome. So to me, that was an eyeopener. And then put all the other studies into context. Those other studies had been the epidemiological ones, very population, big level, showing that people that had regular yogurts had regular cheese. 

Other fermented foods had lower rates of death, heart disease, better metabolic profiles. And some of these we'd done in our own studies at King's using twins, which I was working on for 25 years. 

So, matching the big studies with these detailed ones and then all the little studies around the world with meta-analyses that had studied like 10 or 20 people with a few inflammatory markers all showed the same thing. So you're putting all this together makes absolutely clear that these foods, if you have them regularly, small amounts regularly, will have a significant impact on your immune system and your gut microbiome. We should be learning from our ancestors. 

We should be learning from the latest science. We should all be having at least three portions a day. And that led me to do with the ZOE members. This citizen science project we call pragmatic science. 

So there's no control group, but we got 9,000 volunteers. And if anyone's listening, thank you very much for volunteering. Couldn't have done it without you. Who signed up who, who weren't taking regular fermented foods and said, we want you guys to volunteer to take three a day and do that for two weeks after one week run in on the ZOE app, we asked them to record their mood, their energy, their hunger levels, and any problems like bloating or constipation. They did that every day. 

A thousand dropped out. Understandable. We weren't paying them like they do in these other studies, and they didn't get credits for their university. But these are normal people. These are unlike the studies. They're females, they're males, people aged over 40, regular people who take these foods. And of the five and a half thousand who diligently did this right to the end, a hundred percent completion rate, around 50% showed improvements in mood, energy, hunger, bloating and constipation. 

So to be clear, Jonathan, of the people that completed the study, that means that for the two week trial period, they had at least three ferments a day and they didn't miss a day, and they recorded how they felt on average. 

Around 50% of them noticed significant improvements in a number of key symptoms. The first was mood and energy. They were the first things people noticed. Then they had a actual reduction in hunger, although they were eating more, and they also had a reduction in bloating and also in improvement in constipation. That's pretty remarkable. Right? 

So you're saying that in just in two weeks when I saw those data, that was a real wow factor. And it just showed you that if we can get just the people listening to this podcast spread the word that this is a normal thing to do, eating three ferments a day, we can all, not only improve our inflammation levels at the sort of local level, but actually this can affect our brain, our mental health, in the majority of people taking it in just a few weeks. 

This can have an incredible public health effect, and I just don't think we, we've realized up to now that the huge potential of these fermented foods,

Jonathan Wolf: You started by saying that you thought it was really good for our inflammation and reducing it. Now you're talking about this study that you did with thousands of people through ZOE, and now you're talking about things like mood and energy and hunger and constipation, which seems completely different.

Tim Spector: Yes. What the Stanford study, going back to that one showed clearly improvement in immune health and you also got to shift in your gut microbiome towards a healthier looking microbiome. The two things are linked, and we know that inflammation is key to many features in the body and your gut health as well. 

So if you reduce inflammation, your gut health will also improve. So that would probably explain improving constipation. The mental effects of this, the improvement in mood and energy and hunger are probably through the effects of these microbes on the immune system. 

We think that they directly interacting with the immune system, whether they're dead or alive through most of our immune cells, which are actually lining our gut. And they're sending those signals. We dunno exactly how they do it, but they're sending clear signals to the immune system. 

So all is well that gets transferred to the brain through the vagus nerve and other other mechanisms calming the brain down, reducing so-called neuroinflammation that helps our mood, that helps our concentration, that helps reduce fatigue. So this immune system linked with the gut microbiome is, is the key to really how we feel most of the time and a lot of our problems with modern illnesses due to the fact that our levels of INF of inflammation are much too high.

Jonathan Wolf: So that's amazing. So you're saying that on the one hand you had this sort of super detailed study at Stanford where you can measure all of these inflammatory markers. And on the other hand, you had this study that you led with, 9,000 people and you could see this impact on symptoms that are in the brain, like energy and mood and hunger, but also things like constipation and bloating and a few of those are directly linked. Because you would expect like the gut health improvements and the inflammation improvements to lead to those benefits

Tim Spector: Absolutely, yes.

Jonathan Wolf: So just to maybe wrap back to the original part of the story we were describing all of these amazing things in the food after it's fermented, do scientists understand how this fermented food, like I'm eating this yogurt or this kefir or whatever, actually leads to the benefits you're describing after I put it in my mouth and swallow.

Tim Spector: Not precisely no, but the current thinking is that it's a combination of the microbes and their chemicals themselves that are having this, this effect. And it is so complicated. 

You can imagine how difficult it is to sort out in humans, but we think that the likely place that this occurs, when you say swallow a yogurt and you've got some microbes in it, gets through the stomach wrapped around in the food. 

So you've still got billions getting into your gut when they get to the small intestine, which is the bit above the large intestine, it's not very small. It's actually very large, but there's less of our host microbes to fight it off. 

So we think it probably has an impact there on the immune cells. And something about the lining of the microbes sends signals to the immune cells because we now know that dead or alive. Even dead ones have this ability to tick all the immune cells a bit like a vaccine. And so we think it, a lot of this is due to the having different types of microbe going through your body, having like a vaccine effect on us will tickle the immune system and that will then drive down inflammation and do the other good things that we think, but there's probably likely to be multiple mechanisms that we still don't understand. So it's a very new science in trying to work it out because really we've only just narrowed down what the areas to look at are.

Jonathan Wolf: And I think I remember our colleague, professor Sarah Barry, explaining to me that the food itself is transformed by these microbes. And she was explaining to me that you start with the fat in the milk, it's not very good for you. And then when you look at the cheese, the structure is completely different if you look at it sort of under the microscope as that understood. 

And therefore it's almost like a different food for the microbes in our gut and, and for ourselves. And did I understand that right?

Tim Spector: Yes, there are lots of examples where that is true, that the microbes will break it down into these other more healthy, nutritious benefits for us. In a way, what's happening with the fermented food is it's double fermented, so it's already been transformed before you're eating it. 

So the difference between just drinking milk and having some kefir or yogurt is that by the time it reaches you, it's already in a better state than it was before. So Sarah's quite correct. The structure is healthier as well.

Jonathan Wolf: So in simple terms, does that mean that I'm getting almost a double benefit, that I'm getting both live bacteria that are going to be doing something healthy for me and I'm also getting this much healthier food that is feeding me and my gut microbes.

Tim Spector: Yes, in the sense that food is gonna be easily digested. It's already broken down by the microbes beforehand into smaller pieces, and those nutrients are gonna be much more easily extracted from the food and released into your body and used, in the multiple ways. 

So, absolutely, yes. That's part of the thinking about why the more fermentation goes on, the more you're breaking the food down. People use the analogy with bread, normal bread, you've got lots of gluten, but if it's fermented sourdough bread, the gluten is in smaller chunks and pieces. 

So people will have less problem being gluten intolerant and it's easier for you to then absorb that gluten. So that's the work of the microbes doing that even before it gets into your body.

Jonathan Wolf: Now, one of the biggest questions that we had prior to this episode was around. Eating fermented foods versus probiotics. So, the pills that we buy that say they have all of these live bacteria in which, I definitely took in the past, but don't anymore. How do you compare these like live fermented foods versus probiotics?

Tim Spector: Interesting. There's hardly any studies I could find directly comparing them in a trial. We compared a standard probiotic to our ZOE Prebiotic, the Daily 30, which is 30 freeze dried plants and fiber. And the probiotic was a lactobacillus reuteri, which has been shown to work in 20 diseases.

So we did a direct head-to-head comparison, and our prebiotic won easily, had 10 times the effect on the gut microbiome compared to this probiotic, but we didn't test it against a fermented food. It'd be interesting to see how they match up, but in general, fermented foods have more species of microbe in them. 

In the book, I detail how we looked at 70 different commercial fermented foods. And the range goes from having one species, like in a children's yogurt. All children's yogurts are terrible, to the top one, which had about 80 different microbes in it, which was a kimchi and a water kefir. 

And more is better. More is better. So the more microbes you've got, the more diversity of chemicals they can produce, the more they can help you. And our community is all very different, are unique. 

So if you and I just have one microbe probiotic, it may work on you, but not on me. But if we're having 80, the chances are that it'll probably work equally well on, on you and I. So the one reason to have fermented foods around the probiotics is that the other is you actually get more quantity of them. I would expect if there was direct study done, fermented foods would win.

Jonathan Wolf: It's interesting how understudied this is as you talk about it.

Tim Spector: Yeah, well obviously the companies don't want to do it particularly 'cause, they're worried. And there's a lot of money in probiotics. They don't want to show that just having a, a cheaper food version is gonna do much better.

Jonathan Wolf: And you mentioned earlier this concept of ghost biotics, which I know you've got really excited about because we've actually ended up adding it, haven't we? To the latest version of Daily 30. How on earth can a dead microbe be doing me any good?

Tim Spector: Three years ago I was said there was no point in talking about dead microbes. You should forget. Pasteurized fermented foods, forget all those heat treated kombuchas, the stuff in supermarkets, et cetera. 

But now I've totally changed my mind. Studies are true. They work and the question is how do they work? And the best theory we have is this idea of specific proteins on the cell wall of dead microbes interacting with our immune system. And they have a special receptors there that are picking it up. 

So they seem to be working in that way again, using the immune system. And it makes sense when you start thinking about vaccines. When you have most vaccines, they're either live or they call 'em attenuated, but that just means dead.

 A lot of vaccines you're getting are the dead version of the live one, and it's the same. It's the cell wall, whether it's the virus or the bacteria that is tickling our immune system. So this makes us think that eating fermented foods is a bit like being constantly immunized against our environment and protecting us, and it sort of starts to make sense. 

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So all the foods that are out there that are been dismissed in the past, I think we have to have another look at. And that's exactly why as soon as I made my mind up about this, we put some dead kombucha into our Daily 30 product for that reason, because it may not be quite as good as the live version, but all the evidence suggests it's beneficial.

Jonathan Wolf: So I think a lot of people like me will be surprised because they'd assumed that the reason why you would have a probiotic pill or eat these live fermented microbes is so that then these microbes would like live in my gut and hopefully increase the number of good microbes in my gut because they've all listened to you and other experts explaining that, we need to have more of these good microbes. That was a myth. That's a myth, is it?

Tim Spector: Yeah, it's what is happening. And scientifically, until recently, that's what we believed and a lot of the reasons said, oh, fermented foods can't work because we don't find them staying for very long in our guts. And that was, a lot of people dismissed their biological rationale that way. 

And we have to realize that they don't stay in your gut. They don't colonize your gut. As I said, 96% of the microbes in food are not. The same ones as you find in your gut normally.

Jonathan Wolf: Just to confirm that's, I'm getting this clearly, Tim, you're saying like if I eat one of these super fermented foods with like 80 microbes and I eat it, and then I stop eating it, then a week later none of those microbes will still be living inside my gut.

Tim Spector: Yeah. Generally they don't last. This is what the new science is telling us, that it's really this immune reaction as it's passing through, tickling our immune system, not trying to colonize and take over the rest of our gut. 

And that's a real big sea change in how we're seeing these fermented foods. That's why, I've changed my mind on it. That's why the whole direction, this field is going and is very different. 

That's why I think we're gonna be seeing a lot more of these fermented foods killed or pasteurized back in our, our normal other products because it's a much safer way to, to use them and we start thinking of them as. You know, helping our immune systems rather than colonizing our guts.

Jonathan Wolf: So I'd love to turn to actionable advice now because I'm sure you've convinced a lot of listeners that they need to eat the three portions a day that you've been talking about. So me, let's start, for people who are new to this and then as far as they're aware they're not eating any fermented foods today, where would you start?

Tim Spector: I'd start with breakfast. Always a good place to start because you're at home, you are near your fridge. Start with my classic breakfast. Get some full-fat yogurt. When you're starting off, mix it with some milk because some people find when you start milk kefir it's a bit too sour. But if you mix it with yogurt, that should be fine. You can sweeten it by adding fruits to it, berries, et cetera. That way you've got two ferments. Easily done.

Jonathan Wolf: Because the yogurt's one and the kefir is a second.

Tim Spector: Yeah. And they're separate. They have different microbes in the, they both count.

Jonathan Wolf: Do they?

Tim Spector: They both count.

Jonathan Wolf: So it's a win. You can get two before you leave the house.

Tim Spector: Before you've left the house, you've got two. Exactly. Then it's very easy in your lunch. You can either have some cheese, which, as long as you get anything that isn't completely plastic, avoid things like children's cheeses or pizza cheeses, but even Philadelphia cream cheese. I did a study, we looked at that. That's got three microbes in it, so you can, cream cheese are actually quite good. Any other cheddar or basic one? 

Or, raw milk cheese, even better. That would be your third one. But add to it some pickle, some basic beetroot kraut or some sauerkraut on it. If you're having an evening meal, any form of soup, instead of adding cream to it at the end, you just pour in some more kefi, or yogurt. That's an easy win into your salads. 

You can put, again, these krauts and pickles. I would ask everyone to swap their, stock cube for some miso paste. You can buy miso paste. It lasts a long time, which is this fermented soybean paste that gives umami flavor. That's fantastic. 

I never use stock cubes anymore, and I've just replaced that with a teaspoon of this miso paste at which if you're using it in cooking, it would be dead, but it's still, it gives you, let's give it half a point for that one, Jonathan. And then, you just think that when you're having a salad, can you put in some fermented vegetables into there and start experimenting? 

I don't expect you to eat kimchi straight away 'cause it's quite spicy, but start experiment with small amounts, and if you want to. Start thinking about kimchi, get some toast, put some cream cheese on it, and then mix in the kimchi with the cream cheese. So actually you are giving a mellower flavor to it, and you're getting used to it. 

I managed to convince Davina McCall to start eating kimchi this way, and now she's an absolute addict. So usually people won't like it the first time. It's a bit like toddlers with some new food. You've got to keep going at it, introducing it, doing it in a mild way, and then start thinking about other drinks you can have. 

So, kombucha, the first ones might be a bit sour, but there's some nice fruit ones to start on and you can wean yourself off the sweetness or the artificial sweeteners, just get used to those flavors. Water kefir is another one. TBIs, it's not as common as kombucha, but it has just as many microbes in it and is a easier fruiter flavor for the novice starting off. They're just some of the things that you can do. ZOE Cookbook has got plenty of ways you can incorporate into recipes as well.

Jonathan Wolf: Tim, you've been pitching this to me for a while and I think I'm, everything you pitched me, I slowly start to try and introduce it and I definitely didn't grow up with eating any of these sorts of fermented foods apart from yogurt and, and cheese. It's now really easy to buy them and these things, honestly, I just don't think they were available at all 10 years ago.

Tim Spector: And even people who don't like dairy, so they're often asked this in my talks, I don't have dairy, so I can't have these. No, there's plenty of vegan kefirs and yogurts. The coconut ones are really good. 

It's a slow journey, and I think people will pick the foods and tastes that they like. And people have a different spice threshold, certainly, and a different sourness threshold. Some people immediately love it. Some people it's gonna take more time. But I can tell you, you go to Japan or Korea, you don't find people who don't have either miso or, or kimchi. So in a way, everyone can train their palate.

Jonathan Wolf: Now I'd love to wrap up with the idea of fermenting yourself at home, because I know that you've really got into this, haven't you, Tim?

Tim Spector: I have, yeah. Well, I had to, I'd write a book on it. So I've got to be an expert.

Jonathan Wolf: And I think you have brought some examples of what is literally in your fridge today that you've cycled over with. Is that right?

Tim Spector: A small sample of what's in my fridge? Yeah.

Jonathan Wolf: Oh, how many have you got in your fridge?

Tim Spector: Oh, far too many. At least 20 pots, I'd imagine.

Jonathan Wolf: So now we understand why your wife is very upset about your fridge. So could you maybe take the first one out, explain what it is, and, and maybe start with what you think would be a good place to start.

Tim Spector: Well, let's go with the simplest ferment everybody can do. 'cause Oh, I can't do this. Well, even you can do this one, Jonathan. This is a raw unpasteurized honey, a clear jar, and you put about 10 or 12 cloves of garlic in it. Exactly like this.

And amazingly, after a few days, the microbes in the garlic transform the honey. They start eating the honey, and that produces the perfect environment for these microbes. They soften the garlic, they take away the heart taste of it, and it's a delicious, either hor d'oeuvre or you can blend it up and it's perfect for a salad dressing.

Jonathan Wolf: Can I have a smell?

Tim Spector: Well, you can, you've got to try one.

Jonathan Wolf: Oh, that's exciting.

Tim Spector: Just try one. Jonathan. Don't be scared.

Jonathan Wolf: I am a little scared. I know. It looks like something that has been, ooh. They're quite hard, aren't they?

Tim Spector: Cloves, just go for it.

Jonathan Wolf: I'm gonna go for it. All right. I am not sure that I'm gonna be invited back in the house later tonight. That's pretty good. Nothing like as strong as the garlic is, if I'd eat in that raw,

Tim Spector: well, that's how microbes transform foods into something completely different.

Jonathan Wolf: And the honey tastes different as well?

Tim Spector: Yes. They're both different. I didn't add anything to that.

Jonathan Wolf: You literally just threw garlic and honey. That's it. That's the recipe even I could do.

Tim Spector: Exactly. So everyone can ferment if they really want to at home.

Jonathan Wolf: That's really surprising. So this is where you're saying these microbes do these amazingly complicated things. You just put it in the jar and you left it.

Tim Spector: It's mixed. The microbes and the garlic sitting there bored doing nothing, but you wake 'em up with surrounding them with honey and they go crazy and they come out and they transform the honey. And that in turn transforms the garlic into something, a completely different dish. 

And I tell you, you blend that out and you have that in your salad dressing. It's an amazing flavor. 

What's next? What's next? We've got some sauerkraut. This basically is nothing more than cabbage chopped up and weighed, and you add 2% salt and then you put in a jar and you leave it for a week. 

That 2% salt changes the environment so much that you then get exactly the right microbes leaking outta the cabbage. They eat the sugar that's been leaking out because the salt has released it from the cabbage and the flavors are amazing. And you get all the acidity and it's perfectly safe because they've made it's so acid, nothing, no bugs that you don't want in there will live.

Jonathan Wolf: All right, I'm gonna try Tim's sauerkraut smells like sauerkraut

Tim Spector: There's two types of sauerkraut, obviously the one with vinegar, which is the common cheap one, which doesn't have anything like the flavor and complexity.

Jonathan Wolf: Oh, it's delicious.

Tim Spector: Yeah. There you go. So I've now had two ferments, but anyone can make, I mean, that's the key. So they're the two ones that are so easy. Chop a cabbage and you've got to be able to weigh it. That's about the two skills you need.

This one is slightly more advanced: this is my blob.

Jonathan Wolf: And if you're not watching this on YouTube, it looks disgusting. And Tim is now reaching into what looks a bit like, I won't get you to eat this stuff. Tea, water, and pulling out, which something that looks a bit like a bit of a squid or an octopus or something. It is called, what is that?

Tim Spector: It is called a jellyfish in some countries. Russian jellyfish or Japanese jellyfish. This is a scoby, which is a kombucha mother. Okay. So this is made by the microbes. It's like a shell. They produce themselves. So there's about 50 different microbes in here.

Jonathan Wolf: Living inside that sort of jellyfish thing.

Tim Spector: Yeah, they live inside there and they produce it for themselves. It's like a little protective shell that they live in. So this allows 'em to live for years. I've had this for about 10 years. This one, it has babies and I give it to special friends.

Jonathan Wolf: I've note that I've never been in a special enough friend to get given your Yeah, baby scoby. But on the other hand, it looks disgusting.

Tim Spector: It looks disgusting, but when you add it to sugary tea, so you make a big pot of sugary tea, you just add that to it, leave it for a week, you'll get kombucha and a completely different flavor. And again, once you've got this sorted out, it is actually much easier than it looks.

Jonathan Wolf: And that goes from sugary tea. And we know anything that's just full sugar is not healthy for you.

Tim Spector: To kombucha which is a sour complex. Some say it's the closest you can get to beer and it's good for me and it's very good for you. Yes, lots of studies show it reduces blood pressure, helps your blood sugar level, all kinds of benefits. 

So again, having this in the house, drinks of kombucha, but buy it in the stores first to see if you know what it, what it should taste like. But you, you can, this is incredibly cheap and easy to make.

Jonathan Wolf: And so that, I guess is a brilliant example of the magic of these bacteria moving something really terrible like water and sugar on one hand into something that's suddenly is actually healthy for me.

Tim Spector: Yeah, it actually produces a bit of alcohol as well, usually below 1%, so you can't feel it, but it just giving you an idea of what these microbes are doing. There's yeast in there and they make CO2 and alcohol, so it's very complicated.

And finally, your advanced lesson, Jonathan. So this is miso.

Jonathan Wolf: I say something looks even more disgusting than the kombucha. Alright, so I'm looking at it and it's a sort of brown paste. If anyone has had a small child who maybe ate their food and then regurgitated it, I'd say it looks a bit like that, Tim. It's not the most appetizing thing.

What have I got in front of me?

Tim Spector: What you've got is fermented soybeans mixed with koji fungus. Okay. And salt.

Jonathan Wolf: So I've got fungus, fermented soybeans, and salt.

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Tim Spector: So basically I boiled up a whole bag of soybeans for four hours and then I got some koji fungus, which is coated on white rice from the internet. Mixed them together, added a load, a whole load of salt, and put it in a jar. 

Pressed down, left it for three months. So this is more professional than, all right. It's definitely different to the garlic and the honey. It took me a while to pluck up the courage to do this, but I was so into my miso. 

I was spending a fair bit at the store on Miso. I thought, I can do this myself. And actually, it's really easy to do if you just know the essentials and you've done a bit of fermenting first. So the incredible taste of that compared to just a boiled soybean is amazing. So I want you to just dip your little finger in there.

Jonathan Wolf: Alright. And this is a jar full of fungus, but Professor and Dr. Tim Spec says it's safe and I can try it.

Tim Spector: Yes, you can. All right. And this is what you should be using instead of your stock cube.

Jonathan Wolf: Smells good. Actually.

Tim Spector: Tastes pretty great.

Jonathan Wolf: It does.

Tim Spector: And it just shows you. And if you just had boiled soybeans, they are virtually inedible. And so this just shows you how the microbes and the salt and the fungus and the right conditions just were given time will convert this into an absolute delicious dish.

Jonathan Wolf: And it's definitely like a layer that tastes a bit like soy sauce within this.

Tim Spector: Yeah, it's, well, it's the same basic principle. So there you have it. That's from the easiest to perhaps, one of the more complex ones that you need three or six months to, to make. But you've now got all the tools you need, Jonathan.

Jonathan Wolf: So Tim, thank you for sort of the tour de force, around fermenting. I suspect there are a lot of people listening to this who are now convinced that they should be trying to get their three ferments a day. 

We're gonna try and do a little summary as always, and my biggest takeaway is we should all be having more microbes and fungus in our food, which is basically completely the opposite of everything that was brought up, which is there should be no microbes and fungus in my food. 

And that's because we now know that these really help our immune system. And you talked about the study that you carried out yourself at ZOE with five and a half thousand people who completed this two week study and that sort of, in just two weeks, half of them had these improvements in mood and energy and hunger and bloating and constipation, which is pretty extraordinary. 

And that your understanding of the science is this is really the way that it's both improving the microbiome, our gut health, that's then improving our inflammation and therefore having all these effects on our, our brain. 

I think the other thing that I really take away is that everyone is eating live fermented food. Accepts Anglo-Saxons. And we are the ones who got told that all our food should be sterile. Like we've had fridges for much longer than a lot of other cultures, and therefore we just got rid of all of our fermented food. And like many other things with our modern food culture, it's turned out to really be bad for our health. 

And if we can reverse that and start to reintroduce all of these fermented foods, we're gonna be a much better place. And if you are been thinking, well, I'm popping a probiotic every day, so I don't need this, then you are saying, actually that's wrong.

These fermented foods are much more powerful than probiotics and that's because they have many more live bacteria in them. But also because the food itself is also carrying these helpful properties. 

This is why for many foods when we ferment them, they actually become healthier. And so you were giving this example about things like milk, which you are saying, if you're an adult it's not particularly healthy and then you can turn it into something like cheese or yogurt and, and suddenly it is. And also, and part of this is 'cause we make it so much more complicated. 

And you said I shouldn't be scared of the idea that food has all of these chemicals in there. I think you said like 50 or a hundred thousand chemicals. Actually, if these are natural, the things that are just out there in the foods that we're used to eating, they're sort of what my body and my microbes need. If they're being introduced in ultra processed food, then I'm, I'm not so interested. 

And then I think you wrapped up with talking about, how could we actually achieve this? And you said. I can get two thirds of the way at breakfast. So if I was to have a breakfast that combined like a full fat yogurt, I actually tend to have a Greek yogurt because it's really high in protein. And with kefi mixed, you've already got two of these three. 

If you were to add like cheese or sauerkraut or something at lunch, you've already got to three. And then think about how you could introduce the miso paste, for example, that you just shared with me, which is delicious. 

Think about drinks like kombucha or water cafe. These are all commercially available now, so this is easy to do. There are many of these things which are not really bitter or really hard or really spicy to get into. And if you do this before you know it, your husband or wife will be crossed with you too, because you've got 20 fermenting jars in your fridge and you're experimenting with things that take three months.

Tim Spector: You got it.

Jonathan Wolf: Tim, thank you so much. Thank you for continuing to always explore the frontiers of food and science and for coming back and telling us all about it. And I would say that if you really want to get deep into this subject, Tim has written a whole new book about it and you can understand everything you would possibly want to know about fermented food there.

Tim Spector: Thank you, Jonathan.

Jonathan Wolf: Thank you, Tim. If you enjoyed this episode on Fermented Foods, I know you'll love watching this episode with Tim and Sand or Katz, a food activist and self-proclaimed fermentation revivalist.