Can bread be healthy?

Archaeologists in the Middle East have found fossilized breadcrumbs from over 14,000 years ago. It was the cultivation of wheat for flour that transformed our ancestors from hunter-gatherers to city dwellers.

Today, millions of us start the day with a slice of toast, and most lunches in the U.S. and U.K. are wrapped in a slice of bread or a burger bun as a cheap, flexible, and delicious energy source. This is no surprise.

Modern industrial processes, designed to reduce the time and cost of baking, mean today’s bread would be unrecognizable to our ancestors. These processes were invented with the best of intentions, as growing populations meant more mouths to feed. Without this progress, countless lives might have been lost. 

Today’s bread resembles a sugary drink. It tastes good and looks good on the outside, but it has lost most of its nutritional content. With most of its fiber gone, and no time for bacteria to work its fermenting magic, bread has become a simple starch, rapidly turned into sugar in our blood and offering little to support our gut bacteria. For this reason, bread is increasingly demonized as an evil carb.

In this podcast, Jonathan speaks with two authorities on the subject of bread to find out if it can ever be healthy:

Dr. Vanessa Kimbell is an author, founder of the sourdough school, and a specialist in bread nutrition and digestibility.

Tim Spector is a co-founder at ZOE and one of the top 100 most cited scientists in the world.

If you want to uncover the right foods for your body, head to and get 10% off your personalized nutrition program.


[00:00:00] Jonathan Wolf: Welcome to ZOE science and nutrition, where world-leading scientists explain how their research can improve your health.

It is no exaggeration to say that bread created modern humanity. Archeologists in the middle east have found fossilized breadcrumbs from over 14,000 years ago. It was the cultivation of wheat for flour that transformed our ancestors from hunter-gatherers to city dwellers.

Today, millions of us start the day with a slice of toast and most lunches in the US and UK are wrapped in a slice of bread or a burger bun, as a cheap, flexible, and delicious energy source. This is no surprise, but bread is not what it once was. Modern industrial processes are designed to reduce the time and cost of baking. mean that today's bread would be unrecognizable to our ancestors. These processes were invented with the best of intentions, as growing populations meant more mouths to feed, but this technological progress has a cost.

Today's bread resembles a sugary drink. It tastes good. It looks good on the outside, but it has lost most of its nutritional content with most of its fiber gone, and no time for bacteria to work its fermenting magic, bread has become a simple starch, rapidly, turned into sugar in our blood and offering little to support our gut bacteria.

For this reason, bread is increasingly demonized as an evil carb. So in today's episode, we're finding out if bread can ever be healthy, which types are best than others and what to look out for when doing your groceries shopping. You'll also hear a bombshell about what "baked in the store" really means. Joining me today is Dr. Vanessa Kimbell, author, founder of the Sourdough School a specialist in the subject of bread, nutrition, and digestibility, and Tim Spector, one of the world's top 100 most cited scientists and my scientific co-founder at ZOE.

Vanessa and Tim, thank you for joining me today. As usual, why don't we start with a quick-fire round of questions from our listeners? So starting with Tim. Can bread be part of a healthy diet? 

[00:02:27] Tim Spector: Absolutely. It can. Yes, but perhaps not for everybody and not all the time. 

[00:02:34] Jonathan Wolf: Bread contains gluten. Is gluten bad for most people? 

[00:02:39] Tim Spector: Gluten is not bad for most people. Definitely bad for 1% of the population. And people think they have a problem with gluten more than they really do.

[00:02:50] Jonathan Wolf: Brilliant. And the last one for Tim, is sourdough bread healthy? 

[00:02:55] Tim Spector: It depends how you make it so, good sourdough bread is healthy for most people. Bad sourdough bread is probably as unhealthy as other bread.

[00:03:06] Jonathan Wolf: So Vanessa, our all bread is made in roughly the same way? 

[00:03:10] Vanessa Kimbell: No, absolutely not. There's an extreme difference between different processes of making bread. 

[00:03:17] Jonathan Wolf: Is all sourdough bread the same, however? 

[00:03:21] Vanessa Kimbell: No. Even more confusing. 

[00:03:23] Jonathan Wolf: I think we'll be coming back to that then. Is there live bacteria in sourdough bread in the way that there is in yogurt?

[00:03:32] Vanessa Kimbell: There should be if it's made correctly. 

[00:03:34] Jonathan Wolf: All right. Is there a common misconception about bread that makes you annoyed or laugh? 

[00:03:41] Vanessa Kimbell: Yes. I got really cross when people blame gluten for everything. Gluten bashing. I often shout at my Instagram feed when I see dietitians and nutritionists saying avoid gluten, without the full facts. And I can look like the mad pigeon lady in the park, sort of yelling at the screen because it frustrates me immensely. The amount of misinformation about bread that is out there. 

[00:04:08] Jonathan Wolf: Well, why don't we start with why bread matters and Tim, why is bread important? It's been demonized as sort of the ultimate evil carb. What's the truth about how it affects our health? 

[00:04:21] Tim Spector: And what's important about bread is how much a part of our staple diet it is. So its importance is in the percentage, it makes up of all our energy and all our meals. 80% of British people have a sandwich for their lunch. And that has only happened since the 1980s.

So just that mere fact alone means that the choice of bread has a crucial impact on large parts of our diet, which perhaps it didn't quite have 50 years ago. So I think that's important and it's for many people, it can be the only source of fiber. And it's crucial, therefore that we, understand the bread and we try to work out the difference between good bread, and bad bread and realize that there's this huge range. And so your choice of not only when to eat bread, but also what type of bread to eat are actually crucial to our health. 

[00:05:23] Jonathan Wolf: And I think a lot of our listeners ask whether the bread was basically empty calories. They feel that it makes them put on weight. You know, I think they're coming at this with an assumption that the bread is not a very good part of our diet. And there are many better things that we could be eating. Where are you on that? 

[00:05:39] Tim Spector: Well, I think if you mainly eat bread, that would be true. And a lot of people do eat mainly bread. People who have crisp sandwiches or basically have it three times a day in its worst cheapest form are having a very poor diet indeed.

And this is because that sort of bread is ultra processed and very cheap and has replaced traditional types of bread in the last few years. But even so, it's got good and bad sides to it. So white bread is used really as a substitute for lots of experiments of say sugar, about how you get sugar quickly into the blood system.

And it scores a hundred out of a hundred. On many tests of the availability of sugar in food, because it is quite so available, that starch. 

[00:06:30] Jonathan Wolf: And Tim, can you explain, I'm not sure that everyone will have followed that. How do the bread and sugar, seem like two very different things, could you just unpack that for a minute?

[00:06:37] Tim Spector: Yes. So people don't think of bread as a source of sugar, but as carbohydrates which sugars, are one part. Another part is called starches, which are stored sugars. And, in many types of bread, common white bread, that starch is released as sugar very quickly in the system. And the common supermarket white bread is classical. Your body will very quickly start breaking them down. And that starch gets released into sugar and appears in your blood in 30 minutes, at very high levels. And so it's used in a way as a gold standard of saying, this is the glucose response to sugar, just quoting as an example, that people don't often think of bread as a form of sugar.

So on the one hand, it's a form of sugar, but also it's also a form of fiber. And so there are parts of the bread that don't get broken down or digested, that do reach the lower colon and the lower part of the intestine. And are helpful to the microbes. So depending on that mixture between the carbohydrates, the starch, which produces the sugar, and what proportion is compared to the good bits, the fiber determines very often how healthy or unhealthy that bread is, in very broad terms. 

[00:07:56] Jonathan Wolf: Got it. And we're going to talk with Vanessa, I think a lot now, about sort of how that bread really works. I have to say as a personal anecdote, as someone who discovered that they have really bad blood sugar control, when the first time that I wore a blood sugar sensor on my arm, one of the first things I noticed was this enormous spike that I was having with bread, which I love. So this was a bit of a shock and, you know, one of the consequences of changing my diet over the last few years, is a big shift about when and how I eat bread. And I've definitely noticed that not only did I lose some of this spike, but I've noticed that some of the energy crashes that I used to get after breakfast are definitely lower. It's definitely helped me in terms of thinking about weight. So, you know, there's definitely at a personal level, Vanessa, I've definitely noticed that perhaps the way I used to eat bread was not the best way for me, which I think is a great segue into what really is bread.

So we've already sort of show that there's quite a lot of complexity. Could you help us to understand what it is and in today's world, what is this process by which it ends up in all the stores and the chains where most of us buy our bread and our pre-prepared sandwiches and our McDonald's, and all the rest of it. Help us understand.

[00:09:07] Vanessa Kimbell: Bread has been a staple. We evolved eating bread, but not the kind of bread that you would recognize as being the bread in the supermarket. So even going as far back as neolithic man, and there are some studies that even indicate from our K botany, meaning archeologists finding evidence, but even a hundred thousand years ago, we were actually grinding up Sue grin in caves, indicating that, you know, these initial bread would have been made in just kind of patties and they would have started to ferment.

And, I guess they were easy to carry around almost like biscuits. If you look at the evidence of them, and then we started to evolve into hunter-gatherers evolving into more agricultural practices, we started growing grains and harvesting them and actually consciously making them into bread. And then time went on and you can find evidence from the Egyptians who made bread. And there, often beer is called liquid bread and we have always eaten bread, but not anything like the plastic wrapped, white, nutritional-devoid, things that we buy in a supermarket. 

[00:10:25] Jonathan Wolf: So, what does that mean? How is a normal bread made and how is it even possible for this to be done in this different way? 

[00:10:31] Vanessa Kimbell: This all happened one tiny, little bit at a time, to progress. So the first thing is, is that we had a mass change in population. People started coming into cities and we started having to make bread a lot more. Actually, very interestingly at that time, we went from stone ground flour where the grain is whole. And interestingly enough, you're talking about your blood sugar rising when your grain is still whole and actually bound to that bran and fiber that has a much slower rate of a simulation of carbohydrate because it's still actually part of the original whole grain. What we did is we began roller-milling it and breaking away the fiber from the starch as Tim says, the sugar. And that meant that a lot of the bran, even when you use it as whole grain, Is broken away from starch.

[00:11:30] Jonathan Wolf: And Vanessa, cause you've used the word "bran" can you just help us to understand what exactly that is? 

[00:11:35] Vanessa Kimbell: So essentially we're eating seeds and the outer husk on the seed is protective. It stops insects from eating it, it stops UV radiation, but it contains all of the goodness that we need to nourish our microbes. In our gut. It contains minerals, vitamins, the polyphenols, which are antioxidants.

Again, really all the goodness is in the bran. And we created a process that splits it away from the endosperm, which is the starch. And we created white flour. 

[00:12:11] Jonathan Wolf: And Vanessa, can you help your listeners and help me as well, to understand a bit more what that means. So like, what is the difference between Speltz or rye or flour? Like I remember having when I was growing up and cooking something with my mom. Could you explain, what's the difference between these things, help us understand a little bit about that, and then explore this idea of like mixing it all together as our ancestors did.

[00:12:33] Vanessa Kimbell: We, as bakers are given the most incredible range of flours to bake with, from einkorn, which is the first evergreen, which is sweet and nutty, spelt, again, lovely and nutty. Carastan, which is golden and full of selenium and carotenoids, which are incredibly nutritious as well. We've got this sweetie shop of ingredients, barley, oats, rye, and my goodness, me, you know, ladies and gentlemen, let's mix it up a little, you know, if we're going to make bread, we should really be thinking about involving the entire orchestra when it comes to our bread. 

[00:13:18] Jonathan Wolf: And these are completely different plants? Is that right, Vanessa? Is that the right way to think about them? 

[00:13:24] Vanessa Kimbell: They're all grain, they're all grains. And they all have different attributes and flavors. And each one of them has got what we call different phytochemicals and the different phytochemicals, are what feed the different microbes in your gut. And therefore, if you eat that wonderful, wide diversity, your gut microbes are having a party. They're like, oh, yay! 

[00:13:47] Tim Spector: Yeah. The other thing to mention is that we're talking about the diversity of these whole grains, but modern bread is not whole grains, in general. They are the pure inner part of it. And all the nutritious bit is taken off. So we've lost two parts of this. We've stripped the grain of all the good stuff and only taken the starchy, sugary bit. And we've lost this amazing diversity, so it's a double whammy of the bread that 90% of the people eat most of the time. 

[00:14:18] Jonathan Wolf: And so, Tim, what does that mean when it's arriving in our gut and for our microbes? What's the net result? You touched, I think, on the blood sugar impact, but what does it mean for our microbes and I guess our broader health, this whole process that Vanessa has been describing.

[00:14:31] Tim Spector: Well, it's changing the sugar to fiber ratio, as I said. So the bread that may look healthy is often dyed, you know, dyed brown to make them look healthier and whole grain, a few seeds on the outside, but the inside is still very starchy, very sugary, gives not only the sugar rush when you eat it, but it doesn't have anything like the good complexity of fiber, that's gonna reach your gut.

And then when it does, isn't going to nourish nearly as many gut microbes. So you're not going to get hardly any of the benefits that you would have got with the more diverse, more complex fibers that would feed many more microbes and keep them happy. And those microbes will be converting this fiber into other healthy chemicals, which are really good for your immune system and your metabolism, et cetera. So it's that two-fold difference that probably both impact our gut microbes. One directly affects the metabolism, making you hungrier faster, more tired with that sugar spike, and then the lack of really good high-quality fiber, That's actually getting to your gut a while later. And those two things are having a big impact and is that ratio, and that's the thing you can actually see. if you are lucky enough to get a bread that tells you what's in it, which most don't, you can look at that ratio of the amount of fiber compared to the amount of the sugar content.

And, that's a good guide to whether that bread is going to likely be of any health benefit to you or not. And you know, many of them are not even the federal baguette. We all like a French baguette, but it does very poorly in that ratio. The other point to make here is that most of the bread we eat now, which we buy in supermarkets, is ultra processed. And this is because it contains ingredients that you can't find in your kitchen, yourself often they have more than 10 ingredients, whereas anyone who makes bread side of bread themselves now, you know, it's got flour, water, and microbes, maybe some salt. And this, the fact of all these extra emulsifiers, these other additives, sometimes it contains some artificial sweeteners. All these have effects on your gut microbes that we're beginning to find out are negative. And so. The other hidden side of this is the whole process that keeps this bread looking fresh for two weeks. It means that it has negative effects on your gut microbes when it finally gets there. So many reasons.

[00:17:03] Jonathan Wolf: And so if our listener is going into a store and buying bread, Vanessa because let's assume that not everybody is baking their own bread, that I know we're going to touch on that but imagine they go into the store. Or buy it online as I do what are they looking for to understand the difference, therefore, between a good bread and a less good bread, both, I guess, in terms of that impact on the blood sugar, Tim that you're talking about, as well as the microbes. How can I figure that out? 

[00:17:27] Vanessa Kimbell: Right. So let's start with the first thing of changing attitude. If you were buying a bottle of wine, you'd look at the label, wouldn't you? You look at where the grapes came from. You may read a little bit about the grower. I know Tim would. Red wine is one of the things I think Tim wrote about, which is a delight to say, is actually good for us.

So treat your bread like red wine, you know? You would ask questions. We are assuming that the bread that we're buying is nourishing. We have to stop and look at it and look at the label. So that's your first thing. Never pick up bread without looking at the label and turning it over. Look at the list of ingredients.

Now, the second you see an extremely long list of things you cannot pronounce, or do not recognize, put it down. It doesn't matter what the label says on the front. Put it back. Be prepared to put that right back on the shelf and say, no, I'm not accepting this bread today. I want something that is going to nourish me.

I'm not feeding myself. I'm nourishing myself. So that is about changing your attitude. Then you need to look out for the simplest of ingredients. Let's start with flour and water salts. But the thing that I get really excited about is actually the level of fiber and the proportion of fiber on the label. So I tend to, if I have to buy bread in the supermarket, I tend to look for anything above six grams per a hundred grams minimum.

[00:18:50] Jonathan Wolf: What would be the sort of bread that you'd be advising listeners to try if they're starting out on this journey? 

[00:18:56] Vanessa Kimbell: Oh, the most handsome, sexiest or, no, the one with the label, is looking for whole grain. I'd be looking for the words, whole grain. But even then there are problems that as Tim mentions that some people can fake.

You know, it looks like it could be good. That's why I'm saying you need to get in a relationship with your bread and dig a little deeper, find out a little bit more about it. Cause they can fake that whole grain-ness. 

[00:19:19] Tim Spector: And a few extra tips and tricks. So words like granary mean nothing and the malted loaf is actually just adding probably more sugar to it.

And so there are lots of ways that you're being fooled when you buy bread. And so if there is a label, try to look at the carbohydrate to fiber ratio and that should be relatively low. So it should be around four or five to one for a decent loaf. The worst kind of supermarket bread is about a 17 - 20 to one ratio.

So there's a huge difference in that. Now beware though, that in many supermarkets, that smell of bread hits you as you go around the aisle and those bread they make on the premises, don't have a label and they just put them in bags and you've got no real idea what's in them. And it's all a big con cause that bread is often a year old.

[00:20:13] Jonathan Wolf: Oh really? I was gonna say it sounds good. They made the bread on the premises. Surely this is the best stuff, 

[00:20:17] Tim Spector: no? 

No, it's pre-frozen it's pre-cooked, and basically, they just have to defrost it and give it final toasting. And that's how they get away with making it. This so-called fresh baked on the premises means they also don't have to put a label on it. They don't have to say what additives they put in it. And it's all a giant con, but it does smell nice and makes you extra hungry as you're going around the supermarket. 

[00:20:42] Jonathan Wolf: What about gluten? You mentioned it right at the beginning. I think there are a lot of people who are concerned about being, you know, sensitive to gluten. Bread is the number one thing that people associate with this. How should people think about this? 

[00:20:55] Tim Spector: Well, 1% of people, one in a hundred, actually have a real sensitivity or an allergy to gluten and these people have celiac disease and it's a relatively common if you think one in a hundred is common, auto immune condition, that this doesn't apply to. They will be vomiting. They'll feel really sick. Won't be able to gain weight. There's no in-between area there, but recently in the last 20 years, we've seen this massive increase in gluten sensitivity. which Is people that don't have the antibodies. They're not physically sick, they just might feel bloating or other symptoms when they feel that they're eating gluten. And this percentage is going up all the time. And later surveys around 10% of people say they have gluten sensitivity when these people are actually tested blind with say gluten-free pasta or gluten pasta, and they're not told, which is why about 80% of them turn out not to be gluten sensitive.

They have just got it wrong. Or they've just made a mistake because gluten is associated with other foods. So there's a whole group of people that are mistaken that its gluten that's causing their problem. There are still some people that do have a sensitivity to it, and they may well have other conditions like irritable bowel syndrome or other allergies, which have increased dramatically in the last few years but may just be a general symptom of their problem rather than the cause of the problem.

And that's, I think where most of the scientists and doctors in this field are coming from but no one really believes that gluten is causing these problems. Other than the celiac, it is just a sign that people eating gluten-type foods, or maybe cheap sandwiches or other things that contain it.

They're eating other things along with it that are giving them bad microbes, the worst, the state of your microbes, the less you're able to anyway deal with, some of the foods we eat, and this is a bit of a symptom of the Western gut. But as I said, most people aren't actually mistaken and they're not intolerant of gluten when they're tested in a scientific way. I think that's very important to realize. 

[00:23:10] Jonathan Wolf: If we've cleared that up, Vanessa, can you clear up the sourdough mystery for us? So it's almost impossible now for me not to buy some bread that says sourdough on it. I'm still a bit unclear though, on really what it is. Could you help us to understand? And maybe Tim can help us understand if you know, there's really the health benefits associated with this as well.

[00:23:31] Vanessa Kimbell: So I'm currently finishing my doctorate in nutrition and digestibility of bread. It's taken me a long time and, it's hard work, apparently, they don't give doctorates away. So. Most of my work for the past 20 years has been combining the potential health benefits of sourdough and long/slow fermentation with an understanding of how that plays with the gut and the microbes in the gut and the impact on mental health.

So the first thing to say is, Sourdough is a combination of wild yeast, that's yeast, that's in the air you capture, and lactic acid bacteria, and you'll be familiar with these bacteria because you will have come across them in yogurts. You will come across them in vinegar. These are chocolates, even coffee and tea are fermented. Cheese is fermented. So we're very, very, very familiar with these microbes. And we know that what they actually do is feast on the available sugars. There's a symbiotic relationship with the yeast and they produce two types of assets. Now the first type of asset is the lactic acid which has a kind of yogurty flavor.

And the other acid is acetic acid, and that's more what you would recognize as being vinegar. And when you combine these different assets, what actually happens is the acidity triggers this incredible change that goes on and transforms the dough. It's not the acidity that actually on its own transforms the dough, it's part of the equation, because of course, when you put acid on anything is going to break it down, which is one part of it.

But the other parts of it are very interesting and that is they trigger this amazing thing that's already in the grain and that is enzymes. Now, if you think of enzymes as being like Edward Scissorhands, they chop everything up. And this ability to chop everything up is actually one of the key things that for example, change the way that the flour was structured and the way that the dough behaves. So a really nice example is phytic acid. Now, when you get the acidity triggers the phytase and the phytase enzymes break down something that normally takes the minerals and the vitamins out with it. Also, phytase is something that can also give you wind. 

[00:26:05] Jonathan Wolf: Never desirable for my bread. I feel Vanessa.

[00:26:08] Vanessa Kimbell: No, no. So one of the things that allow people to eat sourdough is that long, slow fermentation and those enzymes neutralize the phytic acid, making it easier to digest, but also unlocking the minerals, making it more nutritious. So. I think that's a win-win. 

[00:26:28] Jonathan Wolf: And how long does this process take? You're describing this long slow fermentation with wild yeast. How does that happen? And can that only happen if I'm sort of doing this at home or in some sort of artisanal bakery, in which case is this relevant for like large-scale feeding of people? 

[00:26:47] Vanessa Kimbell: So it's not just the length of fermentation. You are correct. You can cement a sourdough in a very short space of time. You can make them in six or eight hours, or you can leave them longer. But because of this chain reaction, we tend to think of the longer you ferment the more broken down it becomes. So if you have digestive issues, then fermenting overnight, which is called a retarded method, will generally break the flour down more, making it more nutritious, easier to digest, and is an all-around healthier bread than say something that was short fermented. So within the process of fermentation, there are, you know, short foments and long ferments, but it is using that live bacteria. That transforms the dough.

[00:27:36] Tim Spector: Just to clarify you, might've got the impression that's really complicated, Jonathan, but actually... 

[00:27:40] Jonathan Wolf: It sounded really, really complicated to me. Yes. 

[00:27:44] Tim Spector: But actually Vanessa has actually written a book about how to do this really, really quickly, you know, the 10-minute approach that if you've got everything ready, it just takes you a few minutes to put everything together because the microbes do the work.

[00:28:00] Jonathan Wolf: Give me the 10-minute one. I think you scared me a bit, to be honest like I was getting a bit excited and now I'm retreating. 

[00:28:07] Tim Spector: Well, I now do this, you know, following Vanessa's coaching and you keep a mother in the fridge. From the old, you just keep recycling a bit of the old dough with the microbes in it.

It's resting in the fridge. You mix it with some flour and some water, and then that takes you five minutes and then you come back the next day and then you add more flour, add more water to make up half a kilo, and then you leave it to rise. Then you put it in the oven, then you eat it. And really that's it. The work is done for you by the microbes. And this is why, if you got a regular schedule, now people are working at home, it's dead easy to do this. And you can just mix in anything you really want to, into that flour. And so, regardless of all the chemistry behind it, actually, everyone can do this. And this is what everyone used to do.

 Before 1963, when we all got converted into plastic bread. So that's really important to realize. And I think it has said health benefits, and there are studies showing that people with celiac disease who would normally be vomiting with bread, many of them, not all, but some of them, when they have sourdough bread actually were able to tolerate it, which is really interesting because it means that the protein, in the sourdough bread is very different to normal bread. and the bit that's triggering these reactions is very much less, so gluten is still there, but, the way it's presented is different.

[00:29:38] Vanessa Kimbell: Tim you're absolutely right. 

[00:29:39] Tim Spector: Your own research actually showed that sending out mothers to all parts of the world and getting people to make their own mother because you have to start it somewhere. So everyone leaves a bit of water and flour on the side of their sink and then the natural yeast and bacteria flood in, and it turns out that when you do that, they're all very different and make your bread actually all very different. So all the starters around the world are all slightly different, which is a nice story about how all our guts are different.

And so it's this amazing uniqueness of all these methods that are really important. And some of that it turns out is partly because the microbes on our hands are all very different as well. So not only the microbes in the air and our room, they're all different, but when bakers get around and they start moving, it becomes a bit of a hybrid between your own body's microbes and what's in the dough and in the air as well. So that's why everyone starter is unique and people often swap them around to get very different tastes and flavors because as we know microbes, plus food gives you all these different chemicals in totally unique ways.

But I'd love Vanessa to talk about fake sourdough and how supermarkets are selling to people like Jonathan as sourdough when actually there's nothing live or real about it, other than perhaps the smell. How do they do that, Vanessa? 

[00:31:06] Vanessa Kimbell: So the course I teach is to the royal college of general practitioners, nutrition, digestibility bread.

And we're just getting that reaccredited. One of the things that we tend to find when you talk to people about bread and doctors saying they actually swapped to sourdough or healthcare practitioners says they swapped to sourdough, is that then you cannot simply say swap to sourdough because the fake sourdough that is out there is as bad as the bread that we've been talking about. Refined white carbohydrate. In fact, the most beautiful thing in the world to tell everybody is to swap to sourdough. Wouldn't that be easy? But, we have companies that are faking it, they're using powders that are dead as inoculations as say, 10% of the refined white loaf. So it has exactly the same detrimental effect on your blood sugar. No fiber fuel microbes. The list goes on. I won't go back over that. So when you say to yourself, or a doctor says to, you need to relook at your bread, you have to go beyond looking at the packet. You have to look for real sourdough. Now they're all, ironically, commercial producers of sourdough in large quantities that are making real sourdough.

[00:32:29] Jonathan Wolf: So if I'm at the grocery store, how can I tell whether it's real or fake? Is that back to the number of ingredients on the back of the pack? Or is it something else?

[00:32:36] Vanessa Kimbell: Yes and no, we have no regulation in the UK. In the USA, I don't think it's also regulated or they would have to take a little bit deeper into that right now, but you have to look for the words that tell you that it is real sourdough and long/slow fermented using live culture. At this point, we are completely reliant on the manufacturers, to communicate those facts to us. Just the word sourdough doesn't cut it. So don't believe it. 

[00:33:04] Jonathan Wolf: If it says sourdough pizza, can I now just eat as much of that as I want? And I'm healthy? Because if it's real sourdough, it's all going to be fine. Or is that... 

[00:33:11] Vanessa Kimbell: The thing is Jonathan sourdough itself is a process. Look at what you're actually processing. If you're still processing refined white carbs, no. You know, the best transformation will avoid emulsifiers. I haven't asked or mentioned Tim. We talked recently about a couple of methylcelluloses, which is an emulsifier that's shown to have a negative effect on the lining of the guts. So you're avoiding rubbish like that. You're avoiding plastics, perhaps if you make your own white, but what you're not doing is you're not delivering the most important thing, which is the fiber to your gut. But the thing about the fiber is where the sourdough and this is where I really sourdough, and I was teaching a course of sourdough for mental health not long ago, is that long, slow fermentation actually in vivo animal studies have actually shown that it unlocks four to five times more, and this is really important, this word, bioavailability of the fiber and, we call them phenolics inside. Meaning the chemicals that scavenged the free radicals that might cause cancer. So, if it was a blueberry, for example, your blueberry, instead of eating one blueberry, you'd be eating four or five blueberries. If you ferment your dough because it's actually breaking the fiber down. You see the fiber and all the goodness in the fiber isn't there to nourish our gut microbes. The plants and the way that we grew, didn't grow thinking: "Yay, man, I want to be a sourdough!" It grew to protect itself. So it bound itself up in this fiber, really tightly, but the fermentation acidifies it, breaks it down, opens up the plant structure, and our microbes when they get hold of it, go: "Woo, hello!" 

That's the theory I was working with all of my work because I can see it happening in the test. So coming back to your lovely pizza, Jonathan. No, no sourdough on its own, with white, if you don't have the fiber in there, it's pretty pointless. You might at best increase resistant starch, which might slow down a bit of your blood sugar response and the fat from your lovely cheese might do that.

But no, no, no, no, no. We need to look at the combination of whole grain, live bacteria, and time, and then you can have your lovely pizza with a glass of wine and enjoy it. 

[00:35:37] Jonathan Wolf: So we always like to wrap up with some practical advice, and I think we've touched a lot of this already, but if we do want to eat bread and I think most of us want to eat bread. Are there any other top tips about how to make sure that we can do that in the healthiest way? Maybe starting with Tim?

[00:35:57] Tim Spector: Well, it's just to reiterate that you know, bread is still a good source of fiber and proteins, but if you get the wrong ones, it's going to cause you really bad sugar spikes always choose rye and whole grains and bread with mixed flours and added seeds, when you can. And remember to look at a label when there is a label to try and get as lower a carbohydrate to fiber ratio as possible and a really simple ingredient list. And if you have those two things will give you an idea that if you are buying bread, rather than making it yourself, you've got a chance of getting it right.

And wherever possible do go to a specialist baker, artisan baker be prepared to pay more money for it because you know, you can't make it in half an hour. So it is worth paying that extra money for the slow fermented sourdough bread that we've heard so much about.

[00:36:50] Jonathan Wolf: Vanessa, any other top tips you'd like to add?

[00:36:53] Vanessa Kimbell: Yes. We teach a prescription course and we ask people to just chill and relax and eat their bread with their friends. Sharing bread. And also we call this sequence eating. So if you are faced with having to eat some bread, that isn't whole grain and you need to eat refined bread, and let's face it, you can be in a social situation where this happens and you suddenly feel awkward and weird and rude because you're like, no, thank you. What you can actually do is you can change the rate and the way that your body assimilates your bread by eating a little bit of fiber-rich food beforehand. So you could have small amounts of soup, or you could have some roasted vegetables or something that actually lines your stomach before you eat your bread.

And if you then were to combine your bread with a little bit of fat and protein, that again will slow down the rate your body takes up those carbohydrates. So it's not just the way you make your bread, Jonathan. It's also the way you eat your bread. So you know that pizza you were talking about earlier.

Yup. That would be a salad first, then your pizza with your cheese on top, a little bit of something for some protein, and eating around the table with your friends and sharing. That's the key to bread. 

[00:38:11] Tim Spector: I dip in olive oil personally. That's my trick for that. 

[00:38:14] Vanessa Kimbell: It's actually "pan" is from "pa" and companion, meaning friend. So the actual word itself bread is actually friendship. Something very beautiful to take home and just relax and enjoy the process of eating it. Be in that moment and just connect to eating something beautiful. 

[00:38:36] Jonathan Wolf: That is beautiful. I love that idea. The sad reality is if I eat the pizza, even with the cheese, actually, my blood sugar goes through the roof because I am one of the people that's quite on the extreme of this, but I'm aware of it. And so I, it needs to be something that I do as a treat. Well, Vanessa and Tim, we covered a lot of stuff. So you've made it particularly hard, I'm going to try and summarize the key things we've picked up on today. So firstly bread matters because it's a huge source of the world's calories. We were grinding up grains for bread, tens of thousands of years ago to make fermented biscuits, which is an amazing thing to think about.

And the big change is actually very recently. So when we moved to cities and we moved to this new milling that sort of removed all the healthy outer coat of the seed, and they said loads of benefits, it can be stored longer. It's easier to transport. But we have this byproduct that we lost all the fiber. Sourdough is different because it has this sort of long, slow fermentation.

The ultimate health of it though does depend on what sort of flour you're using. Gluten is not an issue for most of us. A few people have celiacs. I think Tim said that 10% of people have sensitivity, but actually mainly caused by foods other than gluten. So this is sort of symptom, probably of a gut microbiome that's having issues rather than that, the gluten in the bread is the core problem. Now bread can be unhealthy and particularly we turn it into blood sugar very fast. And the final in terms of the top tips to improve your health, if like me, you want to keep eating bread, I think the number one thing. Turn it over and look at the label like you would, if you were buying wine, you wouldn't just buy something that said red wine. If there's a long list of ingredients, put it back on the shelf. Look at the amount of fiber. Sourdough is definitely the way to go, but make sure it's real. And finally, if you are going to eat this really refined bread, then think about what you put around it. And then finally, I think the best thing of all, bread comes from the word friend it's meant to be eaten in this companionship. It's this thing we've been doing for tens of thousands of years. So you shouldn't think about bread as something that's forbidden and you can never have it. Like what we say at ZOE it's about understanding the balance, and nothing should be off.

Vanessa and Tim, thank you so much. That was a fantastic tour. I know there are so many more things we could have talked about. And as always, we look forward to returning to this topic again in the future.

Thank you to Vanessa and Tim for joining me on ZOE science and nutrition today. We hope you enjoy today's episode.

If you did, please be sure to subscribe and leave us a review as we love reading your feedback. If this episode left you with any questions, please send them in on Instagram or Facebook. And we will try to answer them in a future episode. At ZOE, we want to improve the health of millions by understanding the right food for each of us to improve our health and manage our weight.

That's why ZOE always starts with an at-home test comparing you with participants in the world's largest nutrition science study if you're interested in learning more about ZOE, you can head to join and get 10% off your personalized nutrition program as always. I'm your host Jonathan Wolf. ZOE science and nutrition is produced by Fascinate Productions with support from Sharon Feder and Alex Jones here at ZOE.

See you next time.