Instant Genius - How personalised nutrition is transforming our understanding of diet and health

Episode Date: November 3, 2025

Over the past several decades nutritional advice from doctors and expert researchers has largely relied on one-size-fits-all approach – eat five portions of fruit and veg a day, limit your intake of sugar and salt, stay away from overly fatty or processed foods as much as possible – but in recent times it has become clear that, while this is all good advice, the real-life picture is much more subtle. The latest research has revealed that the way we respond to the food we eat varies widely from person to person. As part of our four-part miniseries, Future of Food, we’re joined by Prof Sarah Berry, a nutritional scientist based at King’s College London and chef scientist at the ZOE. She tells us how the gathering of large-scale datasets on dietary habits is changing the way we think about nutritional science, how some of us are more sensitive to the negative effects of certain foods than others, and the key role that advances in technology are playing in the future of dietary research. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Every Monday and Friday, you'll hear world-leading scientists and experts talking about the most fascinating ideas in science and technology today. I'm Jason Goodyear, commissioning editor at BBC Science Focus. Over the past several decades, nutrition advice from doctors and expert researchers has largely relied on a one-size-fits-all approach. eat five portions of fruit and veg a day, limit your intake of sugar and salt, stay away from overly fatty or processed foods as much as possible. But in recent times it's become clear that while this is all good advice, the real-life picture is much more subtle. The latest research has revealed that the way we respond to the food we eat

varies wildly from person to person. In this episode, we're joined by Professor Sarah Berry, a nutritional scientist based at King's College London and chief scientist at Nutrition Company Zoe. She tells us how the gathering of large-scale data sets on dietary habits is changing the way that we think about nutritional science, how some of us are more sensitive to the negative effects of certain foods than others, and the key role that advances in technology are playing in the future of dietary research.

So welcome to the podcast. Thanks so much for joining us. Pleasure, thanks for having me. So today we're talking all about personalised nutrition. So sort of traditionally nutrition advice from doctors or experts has followed a sort of one size fits all approach. And some people might hear that. I think, well, you know, we're all human. That seems perfectly reasonable. But, you know, what are we finding out about this as a sort of headline start to the conversation that really this isn't the case? Yeah, absolutely. We are all so different. We are different in terms many different features that we can personalise on. We're different in terms of our biology. We're

different in terms of how we live our lives. We're different in terms of our dietary preferences, our built environment. And so we need to consider all of this when we think about how we might respond to a diet or a lifestyle intervention. And so when I mean we're different in terms of our biology, I mean our genetics, our microbiome, you know, all of the thousands of different chemicals circulating in our blood and then very simple characteristics like our age, our sex, our menopause status. In terms of how we live our life as well, that's so different how much sleep we have, how stressed we are, how physically active we are in terms of the food that we're eating, how quickly we eat our food, the order we eat our food, the time of day that we eat

our food, the period in which we fast and so much more. So, you know, we've known for years, obviously that we're all different. But what's really interesting in the field of nutritional sciences that we're really starting to understand now that actually our responses to food and our responses to diets is hugely variable based on these kind of factors. Yes, there is an average person. This is a question we get asked a lot. You know, there is the average in the population, the average age, the average height and so forth. But actually, around that average, is massive, massive variability. Yeah, so I think if you were to meet a person in the streets

and say, what's a scientific method of figuring out how we vary from person to person? They say, well, surely that would be by analysing our genes. So are we on the right track there? So our genes explain some of our variability and it will depend on the characteristic or the trait in terms of how much that variability is explained by genes. So, for example, if we were to look at people's height, you would find that a lot of the differences

between one individual and another individual is explained by genes. Not everything, but much of the height is explained by genes. But if you look at other characteristics, whether it's someone's blood pressure, whether it's their cholesterol, whether it's their predisposition to diabetes, for example, or immune diseases, etc.

Yes, some of it is explained by genetics, but actually largely it's explained by what we call modifiable risk factors, by modifiable factors that are around us, that we do have some control over. And I think this is really important because certainly for me, I was a child that grew up in the 70s and 80s, and this was a time of explosion of genetic discovery, where we were told, oh, it's all in your genes.

It's all predetermined. that person, unfortunately, is overweight because it's in their genes, or that person's going to have a heart attack because it's in their genes. Actually, it's not. And I think that this is really empowering that, yes, some of the risk is in our genes, but actually the majority of it is under our control. And it does vary, like I said, from one disease, one condition to another. But on average, about probably 70% of the variability in our risk for many chronic diseases, not all, but many, is under our own control. So let's move on to another sort of topic of research that's been really, you know, talked about an awful lot recently. And that's the microbiome. So what is the microbiome? And what role does it play in our health? Yeah, so the microbiome is a really emerging area of biological research. And the microbiome, very simply put, is the trillions of different bacteria and viruses and so forth that exist.

in our body and on our body. Typically when we think about the microbiome, we think about the gut microbiome, which are these trillions of bacteria that exist in our gut, particularly in our large intestine, our colon. And they play really, really important roles. They play important roles related to our health, so the maintenance of good health, but also related to chronic diseases. And we're only just starting to scratch the surface of our understanding of the role that the microbiome plays in our health. And the role that our diet plays firstly in shaping the microbiome and then the role that those microbes play in subsequent health effects in our body. And so what's really interesting in relation to personalised nutrition and personalized health is that when we think about

how we can personalise in relation to our biology, in addition to our genes, we need to consider our microbiome as well as considering these many other factors as well. So how do we figure out the kind of composition of a certain person's microbiome? So people's microbiome is highly variable. So even in identical twins, and we've studied this from our Zoroa Predict research, identical twins share nearly all of the same DNA when it comes to their genes, but actually their microbiome is really variable. And the reason it's really variable is because the microbiome is very plastic,

is a good word, to say it's very malleable. We can change and modify the composition of our microbiome by diet, by lifestyle, by many, many different exposures. So it's firstly really important to recognize just how variable the microbiome is. Now we can test this using what we call metagenomic sequencing, which is a very fancy test. It kind of blows my mind. I don't really understand it. But you get lots and lots of information on the different bacterial species, the different DNA contained with them, etc. And it tells you about the presence and the amount to the different species of these trillions of different species that are in your guard.

And what we're starting to understand through our own ZOWPredict research, but also all the other research that's going on internationally, is that there's certain species that are involved in certain processes that may have a favourable effect on our health, or conversely, there's some species that are involved in processes that may have an unfavorable effect on our health. And I think where it gets really interesting is that there's emerging evidence to show that we can personalise the microbiome.

i.e. we can change the composition of the microbiome in order to change subsequent health effects. But also, our response to foods can be personal depending on the microbiome that we already have. So a really good example of this is that we have certain species in our gut that are able to convert a particular food compound called soyazaflavones, which have these estrogen-like properties. and some species in some people's gut are able to convert these soyaziflavones into a very active form of estrogen in quite simple terms. And so people that have these species, if they are peri or postmenopausal and are suffering from menopausal symptoms and supplement with soyazoflavones, they will generally experience

a really big reduction in their menopause symptoms. Yet someone else who's lacking these species would have a very limited reduction. and symptoms when supplementing with soy isoflavones. If somebody's in need of these soy proteins, how do we get them inside them? Okay, so if we're thinking specifically, the example I've given related to soyzoflavones, soyazoflavones are a particular chemical that are found in many soy-based products. You can take them as a supplement, and when you supplement with these, if you have the species that are able to convert these to a very active form,

then you're more likely to have a reduction in symptoms. Where I think it gets quite interesting is this whole idea of kind of what we call postbiotics, where in the future maybe we can actually supplement people with the chemicals that these bacteria are actually producing. So we've got the area of prebiotics, probiotics and postbiotics, all of which could be personalized. Prebiotics are basically compounding our food that our bacteria can feed on, and it might be that we can personalise the type of food that we're giving people dependent on the type of species that we have. Probiotics are actually the deliverable of particular

species into our gut, some of which may survive to the large intestine. And again, these could be personalized depending on the presence of certain species that you already have in your gut. Yeah, so you mentioned earlier there the Zohy Predict project, something that you've been part of. It's been going off for several years now. Can you run us through exactly what that is? Yeah, so the Zohy Predict Project is a very ambitious project that we've been running for the last eight years and it's the largest nutrition study in the world. We now have data on over 300,000 people where we've been looking at the different dietary, lifestyle and biological factors that determine in how a person responds to a particular food.

And we've been collecting data at a scale breadth, depth and precision that we've just not done before in biological sciences. And what that's enabled us to do is to look at all of these different features that shape how we respond so differently to food in order to build prediction algorithms, in order to give back targeted advice to individuals that is more likely to work for that individual based on their biology, based on how they live their life,

based on how they eat their food, and based on what current food that they're eating. And what we found from this research is, firstly, that people's responses to food is hugely variable. So, for example, if we were to look at someone's blood sugar response to a standardized meal, and we've given hundreds of thousands of people, exactly the same muffin meal on several days,

and we see that actually it's hugely variable. You get up to a 20-fold difference in how I might respond versus how you might respond to exactly the same meal. What we're then able to do is look at what is it that is determining that variability. What is it that's explaining why I respond so differently to how you respond? And then by looking at what explains that variability, we can then deliver back this quite targeted advice. Now, I do think it's really important when we think about personalised nutrition

and when we talk about our Zoroa predict research to say that there are some fundamentals of nutrition that are applicable to everyone. And so there are features of our diets such as having high fiber, cutting down our sugar, for example, reducing our refined carbohydrate, increasing our plant diversity that's going to benefit everyone. But there's other areas where we can give targeted advice. And I think a really nice, simple illustration of this is related to some. sold. And so we know at a population level that if at a population level, so if you were to look in the UK and say, okay, everyone in the UK can you reduce your salt intake? You would see a reduction

in blood pressure on average across the population. You would see, therefore, a reduction in cardiovascular disease. But actually, there'd be a huge variability. What study shows is about 70% of people might get a reduction. About 30% might get no reduction. And of that 70% that get a reduction. Some people will get a huge reduction, so a huge benefit from reducing their salt, but some people will get very limited benefit. And this is because we know that there's certain hormones involved in your sensitivity to salt. So this is that whole idea of delivering that targeted advice of being able to say to someone, okay, you've got high blood pressure, you are salt sensitive because you do have this particular concentration of that hormone.

Therefore, you are going to benefit from reducing your salt. Yet to another person, you'd say, okay, there's no harm in reducing your salt. And there's other benefits aside from blood pressure of reducing your salt, but you're not going to see quite a big benefit. The person that's told you're going to get a huge benefit, they're going to be motivated to make the change. And I think this is a really, really critical point in personalised nutrition as well. As well as improving the effectiveness of the advice,

what we have to work towards in the UK, in many, many populations, is improving adherence to advice. Less than 1% of people in the UK actually adhere to the core basic dietary guidelines. And so I think that when we think about personalised nutrition, we must consider the power of giving the most effective advice, but more importantly, the power of delivering advice that motivates people to really adhere to that advice and follow that advice. And I think if I was told, hey, Sarah, you know, you are salt-sensitive,

therefore you will benefit hugely from reducing your salt. I'd be really motivated because I know what, hold on, this is going to have a big benefit for me. Say I want to know all this about myself if I'm salt sensitive or whatever. How do you go about sort of monitoring all of these things? So there's been huge changes in how we do this from a research perspective, and some of this is now being applied in a commercial context as well. And I think it's important to kind of look back over the last.

10 years, the transition we've seen in how we do this as researchers. So I spent most of my career at King's College London doing randomized control trials, which are like the gold standard of nutrition research, in quite small numbers, in maybe 20 or 30 people, depending on what outcomes I'm looking at. Now, for looking at a very narrow area or a very small research question, that's fine. But to look at the bigger picture, we need to collect data at a breadth, depth and precision that we just haven't been able to before. And so what's really exciting is that now as researchers, and particularly through the work that I'm doing with the ZO predict study,

we can leverage novel technologies that enable us to conduct these kind of randomized controlled trials that I've been conducting before, but in huge numbers, but also looking at a breadth of different measures. So we've been able to look in 300,000 people at lots and lots of different outcomes using technology such as digital devices, remote clinical testing. So where people from the comfort of their armchair can take a saliva sample for DNA,

they can collect a poo sample, hopefully in their toilet, not in their armchair, but for microbiome testing. They can do a finger prick that we can look at hundreds and hundreds of different metabolites. And people can share this data back with us and we can take a community science approach where we share results back with them,

but they also share with us as scientists, their data. And then building onto these novel technologies is the use of apps, mobile phone apps that we can use for this kind of bi-directional sharing of data, but also real-time monitoring of seeing what people are doing at a given time, what time they're eating, how much they're eating, how much they've slept, etc. And this is transforming the field of nutrition research, as well as transforming the application of these results. so that there are commercial products out there that people can buy that can go and get various tests.

They're not all fully comprehensive, some focus on just particular tests, and then they can be fed back information about their health through an app, typically. When you need to build up your team to handle the growing chaos at work, use Indeed Sponsored Jobs. It gives your job post the boost it needs to be seen and helps reach people with the right skills, certifications, and more. Spend less time searching and more time actually interviewing candidates who check all your boxes. Listeners of this shell will get a $75-sponsored job credit at Indeed.com slash podcast.

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alive and gives it emotional texture. Today, in partnership with French acoustic specialist focal, name audio creates systems that deliver exceptional sound and unforgettable listening experiences at home. Try it for yourself at a focal powered by name boutique. Visit focal powered by name.com for more information. So sticking with the apps, I don't want to use the word gamification, but you get sort of, as I understand, almost like, credit scores for these different things. I mean, is that there to motivate the people? It's like, oh, I've done something good. I can keep doing that now. Yeah, so every app is very variable. There are a lot of apps out there. I am as well as a professor of nutritional sciences at King's

College London. I am chief scientist at Zoe. And we have an app which I have spent the last eight years contributing all the science towards, which I think is an incredible app, but I do need to declare that conflict of interest related to that. We have found through our own work that we've been doing over the last eight years that actually the user engagement, the user experience is so critical. And that feeds back to the point I made earlier that actually the adherence to dietary advice is the biggest problem. And so if a gamified approach is an approach that works for some people, then I think that that's a good approach for those individuals. But we need to use a different approach for different people depending on their own goals, their own motivations,

etc. And that's the kind of approach that we've really focused on with our work at Zoe. So another thing that I've heard that I found really interesting that's kind of taking off is the idea of us having a digital twin. So I find this really fascinating. It's sort of real science fiction and stuff, isn't it? So what exactly is that? And, you know, how can that help us? So a digital twin is really simply put just a digital version almost of yourself. So a digital version of where you are now that follows you over time. So what your current bloods are, what your current genes are, what your current microbiome are, and also what you're doing at that given point in time. And the beauty of a digital twin, it can,

continually evolves because we continually evolve. So if we start a dietary intervention, many of our measures are going to change after two weeks or three weeks or four weeks. And so the beauty of the digital twin is your digital twin evolves and change as you change and as your health journey changes and as your results change and enables us to deliver that very targeted advice at that individual level that is most relevant for you as an individual. Yeah, so you mentioned earlier that one of the issues is adherence to this advice and this data, this knowledge. But could it be that some people don't even get this in the first place and some people are missing out? This will only be available to a select few, like people who are interested in actually finding this out and trying to act on the advice.

Like you said, what did you say? One percent of people actually follow just the general guidelines, which that's quite, quite shocking. Yeah, so it is shocking. Only 1% of people or less follow the core UK dietary guidelines. It's the same in many other populations. The kind of approaches that many of the personalised nutrition apps are using are the kind of approaches that dietitians all over the world have been using for many years, but not everyone can have access to a dietitian. Many more people can have access to apps, and apps can also use very low-cost ways of delivering back the information, they can, as we do at Zoe, use the vast amount of data that

we have, use prediction algorithms, deliver back advice without the need for lots of complex testing as well. The reality is that, yes, at the moment, many of these apps are not necessarily accessible or affordable for everyone, and it's something that we're working on very hard, at Zoe, it's something that many app-based companies are working on. But I think the beauty of certainly the research that we're doing is the findings that are coming out of our research are also being made available to the general population. So we're learning so much along the way that we can feed back to the general population at no cost, whether it's through our podcasts, whether it's through the kind of communications that I do. So for example, speaking to you today

and so many free resources that can educate both healthcare professionals but also individuals without always the need for all of these less accessible tests. Yeah, so having said that, I've got one sort of final question. So what's the future of personalised nutrition? Where is it going to go next? I think the future is really exciting. I think the future is exciting because of the continued evolution of novel technologies and remote clinical testing that allows us at scale and at a lower cost,

year after year, it's becoming cheaper and cheaper to measure different outcomes like the microbiome or, you know, so many other factors. And also the ability to measure lots of other health-related outcomes is just making it even more accessible, more exciting for the future. I also think what's really exciting is our growing understanding of what matters for who. And I think the future of personalized nutrition is really going to leverage the first. full scope of personalisable features. I think five, ten years ago, we were very focused on biological features, on our genes, on our blood markers, on just our microbiome. But I think now that we're really seeing the beauty of personalising on other non-biological factors such as how we live,

and this is an area I'm really excited by. So for example, we know how fast you eat your food matters. We know that if you just slow down how fast you eat your food without even thinking about it, you reduce your energy intake by 15%. We know the time of day that you eat your food matters. So again, nobody needs any expensive testing to be told, okay, you're typically having a big meals or snacking at 10 at night. Try and avoid eating after 9 o'clock at 9. Try not to eat, you know, continuously morning till night.

Try and have fast periods. These are all still personalisable features because how fast you eat versus how fast I eat or how late I eat versus how late you eat is personal to you. And so I really think that's where, for me, the really exciting area of personalised nutrition is, is personalising based on how you live your life, how you eat your food, and other lifestyle factors and not only on biological features. Thank you for listening to this episode of Instant Genius, brought to you from the team behind BBC Science Focus. That was Professor Sarah Berry.

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