The End of One-Size-Fits-All Nutrition: A Scientist's Guide to Personalized Eating in 2025 with Dr. Sarah Berry of ZOE
Show Snapshot:
Is your body craving something different in 2025? Tired of brain fog, low energy, and a body you no longer recognize? We’ve got you! On this week’s show, leading nutrition scientist Dr. Sarah Berry, Chief Scientist at ZOE and Professor at King's College London unveils the science behind personalized nutrition and explains why cookie-cutter diet approaches are failing us. Drawing from research on 70,000 women, she reveals how dietary changes can reduce menopause symptoms by 35% and challenges conventional wisdom about common pantry staples, snacking, and healthy eating. Make 2025 the year you say good-bye to “one-size-fits-all” approaches to food—and hello to a conversation that bridges cutting-edge science with practical, everyday wisdom about food, health, and the future of nutrition.
Show Links:
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Resources from show:
Nutrition Doctor: Seed oils may lower your risk of heart disease | Prof. Sarah Berry
Quotable:
Transcript:
Katie Fogarty [0:00]
Katie, welcome to A Certain Age, a show for women who are unafraid to age out loud. All month long, we are exploring the Science of Living Well in midlife and beyond. I'm your host, Katie Fogarty, and today, we have a truly exceptional guest who's revolutionizing how we think about nutrition and women's health, and is going to help us make 2025 our healthiest year yet.
Dr. Sarah Berry is the chief scientist at Zoe, the science and nutrition company, and a professor at King's College London, and at both she's leading groundbreaking research that's challenging everything we thought we knew about nutrition. In this episode, we'll dive deep into personalized nutrition and explore why one-size-fits-all diet approaches miss the mark. Dr. Berry will share insights from her pioneering research on menopause and nutrition, unpack some surprising truths about fat and cholesterol, and help us understand the science behind smart snacking. She'll also introduce us to the innovative Zoe MENA scale calculator and bust some persistent food myths that might be holding us back.
Whether you're navigating peri and menopausal body changes, focused on heart health, or simply want to understand how to eat better to fuel your body all year long, this conversation is packed with practical science-backed insights that you won't want to miss. I am so excited to be kicking off our 2025 shows with her. Welcome, Sarah!
Dr. Sarah Berry [1:33]
Thank you, Katie. That was a wonderful introduction.
Katie Fogarty [1:36]
Thank you for being a guest. I'm excited to be here. I'm excited to explore all your various areas of expertise with my listeners. And I want to start by asking, what is personalized nutrition? In the US we grew up, at least with the food pyramid and with a whole range of sort of trendy diets, low carb, keto. Why is personalized nutrition the next right step?
Dr. Sarah Berry [2:01]
When we think about personalized nutrition, we think about a diet that is personalized to an individual. Traditionally, we've thought about it in terms of a diet personalized to someone's biology. So Katie, I'm sure you've seen adverts for companies selling diet plans based on a DNA test, or based on your microbiome, or based on a glucose response. And I think when people think about personalized nutrition, a lot of the time, they think it's about that - the diet to have based on our DNA.
But when I think about personalized nutrition, and the way that we're defining it with all of the research that we're doing at Zoe, it's an approach that's personalized on:
1. Your biology (who you are) - factors like your genetics, microbiome, blood biochemistry, age, and menopause status
2. How you eat - the time of day, how fast you're eating, meal ordering, etc.
3. Why you make the food choices you make - preferences, cultural reasons, etc.
4. Your own goals and motivation
I believe that if we can personalize a diet based on who you are, what you eat, how you eat, and why you eat, we can deliver a diet that is:
- Most effective for an individual's biology
- Most importantly, a diet that people can follow
What we know is that less than 1% of people in the UK, and it's very similar in the US, actually follow core dietary guidelines. This is the biggest problem - people are not following a healthy diet. So if we can personalize on all of these features, I think we'll get the most effective dietary pattern for people, but one that they can follow.
Katie Fogarty [3:58]
I absolutely want to explore all the research that you've been doing both at Zoe and at King's College London. But let's pick up what you just said - how do we get somebody to follow an effective, personalized diet? You said we're going to look at timing, we're going to look at the different inputs based on their personal needs. How does Zoe help close this gap between what's optimal and what 99% of us are not doing?
Dr. Sarah Berry [4:24]
It will be different for everyone. The starting point with all of the work that we're doing is data. To unravel the complexity in how we respond to food - and we see like a 20-fold difference in how one person might respond to a food versus another - we need to be collecting a lot of data.
In the research phase, we look at what actually matters and what matters for whom. Based on all this data, we're giving feedback to people in an individualized way - feedback that we believe will offer the most effective advice for them as an individual, based on parameters like:
- Their microbiome
- Their menopause status
- Their age
- Their current diet
- Where they have the most scope for improvement
- Their preferences
For example, there's no point in giving advice about the importance of pulses or chickpeas when it's something that individual might not like. We're delivering it in a personalized way that ultimately will make it as easy as possible for people to follow.
Dietary change, as you know Katie, is so hard. It's so much part of our behavior, our culture, our emotions, our social environment. It's not a simple case of just saying, "Okay, go eat this. Hey presto, done, dusted." You've really got to focus on that behavioral side of things and really motivate an individual and also get through all of those barriers, many of which are unseen barriers.
Katie Fogarty [6:22]
What would be an unseen barrier, Sarah?
Dr. Sarah Berry [6:25]
We could go from one extreme, for example, where let's say we encourage someone to cook a beautiful diversity of plants in a stew, but actually, this person doesn't have access to a cooker. That's an unseen barrier - they don't even have access to those cooking facilities.
Another could be around affordability. It's actually very challenging for people who are heavily dependent on ultra-processed food that we know can be significantly cheaper than unprocessed food. There's:
- The affordability
- The accessibility
- The simple fact that many people have lost the skills - they just don't know how to cook a balanced, healthy dinner
These are all barriers that we just don't talk about enough, I think.
Katie Fogarty [7:14]
So what's Zoe's delivery mechanism? Everything that you're saying - there's multiple inputs. Having a healthy diet is multifactorial. It's our personal taste. Like, I happen to love chickpeas, but one of my sons won't eat them. So of course, we're not going to want to say a healthy diet must include chickpeas if it's just a non-starter for somebody. How are you giving the information through Zoe? Is it through an app? Is it through emails? What's the actual system to put the tools in the hands of your users?
Dr. Sarah Berry [7:48]
Users become Zoe members, so they're part of our Zoe community. This gives them access to a whole range of different offerings:
- Our Zoe science nutrition podcast
- Educational material on our website
- An app
The app involves a couple of phases. One is a testing phase, where individuals collect information about themselves through our app. It involves:
- Testing their gut microbiome
- Testing their glucose responses using a continuous glucose monitor
- Testing blood fat and cholesterol responses using a remote blood collection kit
- Answering questions about their health, preferences, and circumstances (like whether they're eating as a family)
We then crunch all the numbers, analyze all of these different tests, and a few weeks later, people start on the main part of their Zoe journey. This delivers:
- Individualized scores on hundreds and thousands of foods (they can log a picture of their food and get a score based on their biology)
- Targeted advice based on their situation
- Recipe suggestions aligned with their preferences
- Guidance on how to eat (being mindful about eating too fast, snacking late at night, timing of meals)
It's all delivered through an app in a very interactive way, and it's really up to the Zoe member to dive as deep as they want and engage as much as they want.
Katie Fogarty [10:02]
It sounds like Zoe does a lot of the thinking for you, which sounds so appealing because modern life runs at full tilt. We have many thousands of inputs every single day that we need to manage. I interviewed a wonderful home organization expert at the end of 2024 who'd written a book about editing your life, and she shared research that we make 35,000 decisions a day. Many of these are unconscious decisions - are we turning left or right, are we scratching our nose - but it's so hard to make all the decisions we need to in our day. It sounds like Zoe does a lot of the thinking for us: this is where you're at, these are the inputs you've given me, these are recipes and recommendations that make life a lot easier.
Sarah, we're heading into a quick break, but when we come back, I want to talk about some of the research that you've been doing on how nutrition and menopause are interlinked. We'll be back in just a minute.
[Commercial Break]
Katie Fogarty [13:02]
Sarah, back from the break. When we went into it, we talked about how Zoe really helps with decisioning around food nutrition, managing our multiple inputs based on our unique needs. But one thing that's important - we might all have our own unique nutritional needs, but if we are women, we are united by a common experience, which is going through menopause at some point. Menopause is not optional if you're born with ovaries. So I would love to hear more about the study that you have done and how nutrition impacts menopause symptoms. Can you walk us through your findings?
Dr. Sarah Berry [13:02]
Thanks, Katie. We've been doing a huge body of research at Zoe related to women's health, and I'm really proud of this because women are totally underrepresented in research, in health research, in medical research. We have this huge cohort of peri and post-menopausal women that we've been studying - about 70,000 individuals. We've been looking at several areas:
- The prevalence of different menopausal symptoms
- The burden they have on people's lives
- How they relate to diet and lifestyle
- The change in risk factors and chronic disease that occurs during the menopause transition
We're still not talking enough about the fact that when you go through the menopause transition, your risk of chronic disease increases. With that particular research, we studied lots of different risk factors that we call intermediary risk factors for chronic diseases, things like:
- Blood pressure
- Blood cholesterol
- Visceral adiposity (fat around people's waist)
- Inflammation
- Insulin sensitivity
We looked at how these change during the perimenopause transition. What we see is that pre-menopausally, women are doing really well compared to men in all of these risk factors - they tend to have lower blood pressure, lower blood cholesterol, better insulin sensitivity at any given time compared to men.
As soon as they hit menopause, suddenly at that perimenopausal transition phase, these intermediary risk factors change. Blood pressure goes up to at least the level of a man, and sometimes beyond. Inflammation increases, blood cholesterol increases, and insulin sensitivity gets worse.
The good news is that diet plays a huge role in enabling us to reduce this menopause-related increase in many of these risk factors.
Then another area we've been looking at is symptoms, in 70,000 peri and post-menopausal women. We've been examining:
- The prevalence of different symptoms
- The impact they have on quality of life
- The association with diet
What's been really interesting with the symptom data is that typically when women talk about menopause symptoms, people have focused on hot flushes and night sweats - these vasomotor symptoms. Most research related to diet and menopause symptoms has been on these. But what we see in our research is that these are actually the least common - only about 30% of women ever experience these.
What we see in our research is that the huge burden is from cognitive and brain-related symptoms. About 80% of women say they experience:
- Brain fog
- Memory loss
- Fatigue
- Irritability
- Low mood
- Anxiety
- Mood changes
- Sleep disturbances
We found that 99% of women reported having at least one symptom, and 66% said they had 12 or more symptoms. This is why in the UK, and there's similar data for the US, 10% of women say they leave their job during the perimenopausal transition because of these symptoms - they are so prevalent and burdensome on individuals' lives.
But the good news is we have some really exciting data showing that we might be able to help these symptoms through diet.
Katie Fogarty [17:07]
Well, I cannot wait to explore that with you. I'm nodding my head to everything you just said. The data is similar in the US about people leaving work due to menopausal symptoms. I've done probably 70 shows on menopause, and I've been in countless rooms with women over the last four years since I started this podcast. Every single thing you said has been borne out anecdotally.
Women are experiencing brain fog, energy issues, low libido. I had the pleasure of interviewing one of the US's top menopause advocates, Tamsin Fadel, and when I asked her what was the number one concern she's hearing from women as she's been circulating the country with her PBS menopause documentary, "The M Factor," she said they just don't feel like themselves. And not feeling like yourself is that constellation of what you just outlined - the brain fog, irritability, exhaustion, low energy, this sense of dislocation.
It's not surprising to me that 80% of women are experiencing this constellation of symptoms. So what can we do to address these with our diet? I would love to hear from you.
Dr. Sarah Berry [18:20]
The way you described it - not just feeling like yourself - and the way Tamsin describes it, I think, is spot on. This is what makes it very difficult. There isn't a test to say you're peri and post-menopausal. Billions of pounds or dollars are wasted each year on people testing their estrogen levels, but they fluctuate hour to hour, day to day. It is that whole "I'm just not feeling like myself."
Can I do anything about it? Well, yes, our research shows that you can. We looked at the association of symptoms across lots of different exposures, as we call them. We looked at how diet was related to symptoms, how people's BMI was related to symptoms, whether they smoked, their physical activity. Let me run you through the top line of those results, and then we can dive deeper into the diet results.
What we found was:
- People who smoked had more symptoms and a greater burden of symptoms
- People who were less physically active had a greater prevalence and burden of symptoms
- There was a really strong association between BMI and symptoms
For example, people living with obesity had about a 70% higher chance of having brain fog compared to those of normal weight. We see that for other symptoms as well.
Then we did a deep dive looking into diet. We looked at both peri and post-menopausal women separately in our 70,000 individuals, because perimenopausal women have been quite understudied in the field of diet and menopause. Generally, most studies have been undertaken in post-menopausal women, but we know it's that perimenopausal transition that can be two to ten years that's particularly burdensome.
What we found was that diet was really strongly associated with menopause symptoms. People who were on a generally healthy diet - a Mediterranean-style diet rich in plant-based foods, healthy fats, and a variety of different foods, low in ultra-processed foods - had significantly reduced likelihood of having a whole array of symptoms, particularly the brain-related symptoms like brain fog, memory loss, irritability, etc.
Then we followed a subgroup of 4,000 peri and post-menopausal women over 12-18 weeks. We measured their symptoms at the start of this period and measured their diet - most were following a very typical UK/US style diet, which we know isn't particularly healthy. We then asked them to modify their diet by following the Zoe personalized nutrition program, which has the same underlying principles of a healthy diet: high fiber, plant-diverse, healthy oils, with limited ultra-processed food.
At the end of the 12-18 weeks, we asked them again about their symptoms and diet. What we found was that, on average, those following the Zoe program had an overall reduction of about 35% in their symptoms. The reduction was strongest for the brain/psychological symptoms - brain fog, memory loss, irritability, low mood, anxiety, etc.
We looked at results according to whether women were:
- On HRT or not
- Perimenopausal or post-menopausal
For perimenopausal women not on HRT, we saw an average 35% reduction in symptoms. If they were on HRT, they had a lower initial starting point for symptoms but still had about a 35% reduction. Post-menopausal women had a slightly lower starting point but still saw around a 30% reduction in symptoms - just from improving their diet.
It's important to caveat that this is not a randomized control trial - this is an observational study. To confirm that this is truly causal, we would need to do a clinical trial comparing one group following a typical UK/US diet with another group on this healthy program. But what's really exciting is that this data reaffirms other studies showing that those following a Mediterranean diet have a lower prevalence of symptoms.
Katie Fogarty [24:00]
It's such marvelous news for people who are not interested in taking HRT. Obviously this is an observational versus a clinical study, but I know from recording the show and from being in different rooms of women in the menopause space that not everyone can take HRT and not everyone wants to. It's important to recognize that there are other tools in our toolkit that can help us with some of our symptoms, and diet is one of them.
You flagged that this was most impactful according to your studies on some of the brain, the neurocognitive symptoms, and that it helped with things like brain fog and sharpness and maybe word finding. What are the types of foods that we're eating that help improve our brain function and help us eliminate brain fog?
Dr. Sarah Berry [24:51]
We saw this improvement even with quite small dietary changes. We're not talking about someone going from a typical UK or US diet - and by that, I do mean quite a poor diet, many of your listeners probably are on a slightly healthier diet than that - to a diet that's devoid of any salt, sugar, or processed food. We saw this improvement with quite small changes, and I think that's the first thing to really focus on - actually just small changes are going to help.
We looked at individual dietary components to see which were most strongly associated with improvements. Again, this is observational, not a clinical trial, but certain food groups really stood out:
- Nuts and seeds
- Vegetables and fruits as a whole group
- Pulses (things like chickpeas, beans)
Katie Fogarty [26:27]
We heard a lot of this similar talk when I interviewed Dr. Annie Fenn a couple of months ago. She is the author of "The Brain Health Kitchen," and she echoed exactly what you said and also shares some really wonderful recipes in her cookbook and on her website.
You mentioned nuts and seeds are good for your brain, which is good news for me since I like both. But this brings me to a question about seed oils. We hear a lot of buzz around seed oils and whether or not they're good for us. One of my three children has really taken a stand on this, and we are almost seed oil-free in my home to accommodate that kid's preference. I've done a lot of reading on this, and I would love to hear your perspective on seed oils.
Dr. Sarah Berry [27:21]
I've actually recently produced a podcast on seed oils because it's something that, before I started working in personalized nutrition and on menopause with Zoe, I spent a lot of time working on and done quite a lot of RCTs on. This is on the Zoe Science and Nutrition podcast.
I don't hold the view that many people hold if you go onto social media. I do not believe that seed oils are toxic. I do not believe that based on current evidence, they're bad for us. Based on the current evidence, including evidence from my own clinical trials as well as many other published research, seed oils are actually a very healthy part of a balanced diet.
I think that the evidence is misinterpreted, and we need to be very cautious demonizing seed oils because we then have to think about what we're going to push ourselves to eat instead. The kind of king or queen of all oils is extra virgin olive oil, and I would advocate that we should be eating as much of that as we like and enjoy. We know it's really good for us.
Seed oils are very high in a fatty acid called polyunsaturated fatty acid. This is part of the reason they're demonized, but actually it's the reason that I think they're so healthy for us. We know that polyunsaturated fatty acids have a very potent cholesterol-lowering effect. Having a decent amount of seed oil in your diet can significantly reduce our blood cholesterol, which we know is linked to heart disease.
There is evidence talked about in terms of seed oils being associated with the pandemic of ill health we're living in. What we do know is that over the last 50 years, our intake of seed oils has increased dramatically - about 100-fold compared to what it was 50 years ago. In line with that increase in seed oils is increased obesity, increased levels of type two diabetes, increased cardiovascular disease, etc. But what's also increased is all of these heavily processed unhealthy foods.
Unfortunately, a lot of seed oils are found in these heavily processed unhealthy foods. But if we disentangle the effect of the seed oil from all the other unhealthy ingredients in these heavily processed foods, I believe that they're a healthy component of our diet.
There's one study that people often refer to as an example of why seed oils are bad for us. This was a study done in the 1960s where men who had had a previous cardiovascular event were randomly allocated to follow a high seed oil diet, and they were given the seed oils in the form of either a spread or the oil itself.
At this time, seed oils were used in spreads having undergone a process called partial hydrogenation. The process of partial hydrogenation produces industrial trans fats, which we know are so bad for us - they increase our cholesterol, they increase inflammation, they affect so many different areas of our health negatively.
Katie Fogarty [31:25]
For clarification, and by the way, this is all good news for me because when you eliminate things from your home, it's very tricky to manage diet and cooking. We're a family that cooks, and it was tricky to accommodate this preference, which we were willing to do because it was important to one of my sons. But what are seed oils? Let's fill our listeners in on what those are, and what are ones that you would recommend as being an important part of a healthy diet.
Dr. Sarah Berry [31:55]
Seed oils are the oil from a seed of a plant. In the UK, the most commonly consumed seed oils are:
- Rapeseed oil (also known as canola oil)
- Sunflower oil (second most common)
In the US, the most common are:
- Soybean oil (comes from the seed of the soybean)
- Sunflower seed oil (second most common)
There are different ways that you can produce seed oils:
- Cold pressing: literally squeezing the seed and the oil comes out. That's very inefficient - a lot of oil gets left in the seed, which is why cold-pressed seed oil is quite expensive
- Commercial production: uses solvents as well as physical means to extract the oil, making it very efficient and getting all of the oil out
They're used in many different foods and applications in cooking, whether it's frying or being added to foods by the food industry. Which oil you use will depend largely on the function you need it for:
- Soybean oil and rapeseed oil tend to have a decent amount of monounsaturated fatty acids, so they're a little bit more stable and quite good for frying
- Oils with more omega-6 and polyunsaturated fatty acids have a slightly different smoke point, so they're slightly less stable for cooking
- There's also the factor of taste - many seed oils like soybean, rapeseed, and sunflower tend to be quite odorless and tasteless, unlike sesame seed oil or extra virgin olive oil which are very fragrant. This makes them very good vehicles to use in many cooking applications
Katie Fogarty [34:14]
Thank you for this. This has been a wonderful primer on oils. I don't know if you knew you were going to be our oil expert today!
Dr. Sarah Berry [34:20]
No, I didn't! I love talking about oils. Just one thing actually, while we're talking about it - something that I get asked so much about oils is "Oh, but they're dangerous to cook with, aren't they? They're really dangerous because they get oxidized."
Well, firstly, oils and plants, just like humans, are so clever. Plants make sure that their oils are packed with antioxidant vitamins. Sunflower, soybean, rapeseed - all of these oils that we typically cook with are packed with vitamin E, for example, and other antioxidant chemicals. So actually, that keeps the oils quite stable.
For proper storage and use:
- Don't leave them out in the light
- Don't leave them out in the air
- Don't leave them in a warm environment for excessive periods
- Keep them in a dark bottle in the cupboard with the cap screwed on
- They will be very stable when heated
- Only if you're repeat heating at excessive heat the same oil time and time again might you get the production of compounds that we know are unfavorable for health
- In most home kitchen uses, you would not be producing these harmful chemicals
Dr. Sarah Berry [35:57]
We did a really deep dive in our Zoe predict cohort into snacking habits, and it's actually really understudied. Partly it's understudied because there's no clear definition of a snack. Is a snack an eating event between a meal, or is a snack a type of food? If you have a crisp, is that a snack?
So that's why there's actually very little research out there - if scientists don't agree on a definition, then it makes it very challenging to research it. We define snacking in our research, and I think generally now this is how snacking is being considered, as an eating event between a main meal (breakfast, lunch and dinner). Any eating event between that we define as a snack.
What we found in our research is that:
- 20-25% of our total energy in the UK and US comes from snacks - that's huge, a quarter of our energy coming just from snacks
- That's as much energy as we get from lunch, for example
What we also found was that snacking itself wasn't a problem. People often say, "Oh my gosh, how we eat in the US and UK, where we're grazing constantly and constantly eating is a real problem. This is why we have these increased rates of obesity, type two diabetes, cardiovascular disease."
What our research showed was that as long as you were snacking on healthy foods, having multiple eating events (multiple snacks) throughout the day wasn't a problem. Where it became a problem is:
- If you were snacking on unhealthy foods
- Particularly if you were snacking late at night
We found that:
- 30% of people were snacking after 9 in the evening
- 50% snack after 6 in the evening
- If you were snacking after 9 in the evening, even on healthy snacks like nuts and fruits, those individuals had worse health, worse metabolic health
- They had worse insulin sensitivity
- They had worse blood lipids
- They had higher body mass index
This snacking research showed us that snacking itself isn't a problem, but:
- Be very mindful about what you're snacking on
- Be mindful of the time of day that you're snacking
Then Katie, where it gets really interesting is we also did some research as part of a project that I ran at King's College London a few years ago. We ran a clinical trial where we asked people to modify their snacks:
- One group: eat the typical US/UK style of snacks (we provided these to individuals), eating 20% of your energy from these snacks
- Another group: eat almond nuts instead of typical snacks
- We monitored lots of different health outcomes over six weeks
What we found is, just by changing your snacks to almond nuts (and we asked people, don't change anything else in your diet), they significantly improved a whole host of different health outcomes:
- Improved blood lipids (cholesterol)
- Improved insulin sensitivity
- Improved blood vessel function (using a specialized measure called flow-mediated dilation)
Katie Fogarty [40:11]
That is absolutely fascinating, and this is a serious question - what if the almonds are covered in chocolate? Chocolate-covered almonds are my preferred snack. I'm assuming that these were chocolate-less almonds.
Dr. Sarah Berry [40:28]
So in our study, they were chocolate-less almonds. But it depends on the type of chocolate, Katie. If you had almonds covered in a very good dark chocolate that's rich in polyphenols, then actually that could be really beneficial. We know that dark chocolate that's high in polyphenols can actually be really good for us. We know it can reduce our risk of cardiovascular disease, because the polyphenols themselves are these magical substances we call bioactives that really impact our health beneficially.
Now, if instead they're coated in a very typical UK/US chocolate that's packed with sugar and saturated fat, less so. But it's all about balance. If it's a case of either having just the chocolate, either the not-so-healthy chocolate, or having almonds coated in chocolate, then absolutely have the almonds coated in chocolate. I'd rather you go for that than not have almonds full stop.
Katie Fogarty [41:28]
Or a bag of potato chips - absolutely another that was probably on the unhealthy snack list. So polyphenols, these are things that are good for our body. We're beginning, at least I am, to add these nutritional sort of glossary terms where we recognize what we need to be looking for in our foods.
But one of the things I know is a challenge when we're trying to make healthy food choices is that sometimes what's labeled on a box or on the back of the bag doesn't always tell the full story. What do we need to be paying attention to to make smarter decisions when we're not at the produce aisle? I mean, the produce aisle is pretty clear - a head of broccoli is going to be a head of broccoli. But when we're buying packaged goods, what do we need to be paying attention to?
Dr. Sarah Berry [42:15]
I mean, I think this is a difficult question because yes, you're right - we all know that we should be eating minimally processed foods, trying to avoid really heavily processed, packaged food that's got hundreds of different additives and emulsifiers. The reality is, though, often those foods are:
- Cheaper
- Easier
- More convenient
Particularly if, like me, and you probably, we've got kids, we're working full time. I do think it's a challenge, but I think where we can, going for whole foods as much as possible is really important. The reason for this is because they have their matrix intact. This is something I spent a long time researching, looking at food structure.
Something we focus on a lot right now, particularly as our awareness about ultra-processed food is growing, is around additives and emulsifiers. If you look at the back of pack labeling, if it's got lots of chemicals you wouldn't have naturally in your kitchen, or it's got loads of different ingredients, perhaps it's not so good for us.
So I think you can:
1. Look at whether you recognize all the names of these ingredients
2. Check what kind of additives and emulsifiers are present
3. Look at whether you actually recognize this food - does it resemble the food it originally came from?
Katie Fogarty [43:52]
What do you mean by structure of food?
Dr. Sarah Berry [43:55]
Structure of food means the food matrix - the actual physical form that the food is in. I can give you an example from work that we've done. If we take almonds, since we've been talking about them in relation to snacks, if you eat a portion of almonds (28 grams), what the back of pack label tells you is that there should be 170 calories per serving.
But when you eat whole almonds and chew them, you swallow the almonds when the particles are about one millimeter in size. If I was to say Katie, at the point at which you're about to swallow those almonds that you've just chewed, spit them out, you'd have lots of these one-millimeter chunks of almonds. For anyone that's got kids listening, if you've ever given nuts to your kids, when you look at their poo, which obviously as parents we often do when they're young, you will actually see chunks of nuts there.
What this means is a lot of the structure of the almonds, this food matrix, is remaining intact. The cell particle size of most plant foods, and in this case almonds, is tiny - less than a grain of sand. So when you're swallowing the almonds, you've got thousands of cells that are intact, that have these very rigid cell walls, and the fat, carbohydrate, and protein is within these cell walls.
As they pass through your gut:
- You'll digest some of the cell walls
- You'll digest some of the fats, protein and carbohydrate
- But actually a lot comes out in the poo
What that means is:
- Back of pack labeling says 170 calories per portion
- You only absorb about 120 calories
- About 30% of the calories are actually excreted because of the structure of nuts and their rigid cell walls
Now, if I was to commercially process these nuts and grind them so they're smaller than what would be in a nut butter - using industrial processes where you break every cell wall open to tiny grains of sand - all of the fat is therefore available to be absorbed. You would actually absorb 168 calories. But the back of pack labeling for these really finely ground almonds would be exactly the same, because you've got exactly the same ingredients, just in a different physical structure.
Katie Fogarty [46:45]
That's so fascinating. So people would need to be doing a little math to understand that. We're talking specifically about calories, like the 170 calories of the almonds. But I'm assuming that the nutrients differ too based on what's either being absorbed by the body or not. This is important because if we are looking to fuel our body with certain levels of nutrients, we need to better understand that simply because we're eating whatever's in that label package, the level of nutrients we might expect - I'm assuming the same thing is true, that we're not actually absorbing that level of nutrients. Is that correct?
Dr. Sarah Berry [47:23]
It's a double-edged sword. In the obesogenic environment that we live in, where many people are trying to be careful about how many calories they're eating, you would want to say, "Okay, eat the whole almonds, because 30% of the calories are coming out." But the double-edged sword is that all the vitamin E, for example, that's contained in the cell walls where the fat is, is also excreted when that fat is excreted out.
This principle applies to lots of other foods. Take oats, for example - I've done a study on this where I fed people:
1. Whole large oats (the steel-cut oats that our grandparents might have had)
2. The next day, exactly the same oats but ground up in a blender
We see a big difference in metabolic responses:
With the large steel-cut oats:
- Small, slow increase in blood glucose (favorable)
- Absorbed lower down the gastrointestinal tract
- Packed with fullness receptors, so you feel full for longer
With the ground oats (same ingredients):
- Absorbed more quickly
- Big peak in circulating glucose
- Absorbed higher up the gastrointestinal tract
- Less release of fullness hormone
- You feel hungry sooner
This is another great example of how you could have two things that back-of-pack labeling shows to be identical, because they're the same starting ingredient with the same nutrients, but how your body processes them and how they make you feel is actually very different, purely based on the physical structure.
Katie Fogarty [49:46]
And how does the average person sort this all out? Because, as we just said a few minutes ago, everyone's got a lot on their plates. They've got kids, jobs, calendars full of to-dos. When we're trying to assess what we're eating, how can we manage these sort of lack of clarity?
Dr. Sarah Berry [50:07]
I think sometimes we're making it too complicated. If we want to optimize, then yes, it does become complicated if we want to optimize for every tiny health gain we can get. But actually, if we just go back to really healthy basic eating principles, you're getting 99% of the way there. And these healthy eating principles are as boring as hell, I know-
Katie Fogarty [50:38]
No, tell me! This is what you're here for, Sarah. There's no silver bullet.
Dr. Sarah Berry [50:42]
It's the boring message of balance, of having balance. A little bit of what's bad for you occasionally is fine - don't worry about that. It's about having:
- Lots of unprocessed, plant-based whole foods
- Nuts, seeds, pulses
- Fruits, vegetables
- Healthy oils (extra virgin olive oil, seed oil)
- A wide variety of foods to get different phytochemicals and bioactives
Then limiting:
- Refined carbohydrates (white breads)
- Heavily processed foods (pastries, cakes)
- Processed red meat
I don't think there's much more to it. The key things are:
- We need to be getting more fiber
- We need to be getting diversity of plant-based foods
- We need to be limiting our sugar, saturated fat, and salt intake
If we go for as much whole plant-based foods, with some healthy oils, a bit of fish if you like, some chicken and some red meat (as long as it's not processed), then fine - add that in occasionally as well.
Katie Fogarty [51:56]
Sarah, that is a wonderful note to end on that feels manageable and doable, and it's just a great reminder and a great reset as we look ahead to the rest of 2025 and choose options that make us feel our best, fuel our energy, and help us have a joyful life.
I am very excited and appreciative that you are kicking off the year with us, and that you came on to share about the work of Zoe and share so much of your nutrition smarts. Before I say goodbye and let you go, where can our listeners learn more about Zoe and learn more about your work?
Dr. Sarah Berry [52:33]
Thanks, Katie. We have:
- A science and nutrition podcast called "Zoe Science and Nutrition" (weekly podcast with scientists and experts)
- Website: join.zoe.com
- For those interested in menopause: free online tool called the Menoscale calculator at zoe.com/menoscale (measure and track your symptoms)
- Zoe Instagram account
- My own Instagram account: @dr.sarah.berry where I give updates on new research
Katie Fogarty [53:27]
Thank you so much, Sarah.
Thanks, Katie.