ZOE Science & Nutrition - The truth about the Mediterranean diet

Episode Date: January 24, 2024

Each day this week, we examine one of the world’s most popular diets. Putting the latest scientific evidence under the microscope, we’ll discover these diets' true impact on your health. Today, we’re talking about the Mediterranean diet. This indulgent diet champions vegetables, beans, fish, and even red wine, all with a liberal helping of extra virgin olive oil. However, this relatively high-fat diet undergoes many regional adaptations, and the wide range of options can be confusing, even intimidating, if you’re not that confident in the kitchen. In this special episode of ZOE Science & Nutrition, Jonathan is joined by Christopher Gardner, Professor of Medicine at Stanford University and the Director of Nutrition Studies at Stanford Prevention Research Center. Together, they discuss this diet's potential health benefits and pitfalls.  🌱 Try our new plant based wholefood supplement - Daily 30 *Naturally high in copper which contributes to normal energy yielding metabolism and the normal function of the immune system Learn how your body responds to food 👉 zoe.com/podcast for 10% off Follow ZOE on Instagram Timecodes: 00:00 Introduction 00:42 Topic Intro 02:42 What is the concept of the Mediterranean diet? 04:22 Why do we have more data on this diet? 06:08 What are the main differences between this and other diets? 07:30 How much meat is in the Mediterranean diet? 08:20 Is the Mediterranean diet a “whole food” diet? 09:10 How do whole grains fit into this diet? 10:06 Where do oils and legumes come into this? 11:31 What happens when you switch from a US/UK-centric diet to a Mediterranean diet? 13:23 What is going on inside the body to deliver the health benefits? 14:08 What are the possible challenges of the Mediterranean diet? 16:05 Keto vs. Mediterranean diet study 19:09 What's the verdict? 19:50 Outro Mentioned in today’s episode:  Adherence to Ketogenic and Mediterranean Study Diets in a Crossover Trial: The Keto-Med Randomized Trial, from Nutrients   Effect of a ketogenic diet versus Mediterranean diet on glycated hemoglobin in individuals with prediabetes and type 2 diabetes mellitus, from the American Journal of Clinical Nutrition                                                                            Have feedback or a topic you'd like us to cover? Let us know here. Episode transcripts are available here.

Hello and welcome to Zoe's Science and Nutrition and our special daily series about diets. Each day this week, we're examining one of the world's most popular diets, putting the latest scientific evidence under the microscope. We'll find out these diets' true impact on your health. I'm your host, Jonathan Wolfe, and I'll be joined throughout this series by Professor Christopher Gardner. Hello, Christopher. Good to be here, Jonathan. Christopher is a professor of medicine at Stanford University

and the director of nutrition studies at the prestigious Stanford Prevention Research Center. He's one of the world's leading researchers on how our diet impacts our health. So what's on our plate today, Christopher? In episode six, Jonathan, we're taking a trip to the Mediterranean for lunch. Christopher, I definitely know this one. You're talking about the Mediterranean diet, right? Yes. So we recently had on the show Professor Walter Willett from Harvard, and he's sort of widely hailed, I think, as sort of the godfather of modern nutrition. And he's been talking about the benefits of the Mediterranean diet for decades now.

But what exactly is the Mediterranean diet? And I like to ask this of all Americans because I feel I've visited lots of places in the Mediterranean and they seem to eat very different food if you're in Spain or Italy or somewhere like Morocco. I think this is an excellent question to ask, and the answer is olive oil. It is only olive oil. Eat whatever you want during the day, and at night, put a jigger of olive oil next to your bedside, gulp that down, and in the morning, you can claim your Mediterranean. I feel that maybe there's a bit more to this. Hi, I'm delighted that you're here to find out if eating the Mediterranean way can

improve your heart health. If you haven't already, please hit follow in your podcast player so you'll know whenever a new episode arrives. This will help us and continue our mission to improve the health of millions. I don't think the average person could describe the Mediterranean diet to you. We actually have several Mediterranean diet scores. And you should eat more vegetables, more fruits, more beans, more whole grains. They have a controversial one where they say you should have some alcohol. Not none, and not a lot, but you actually get dinged for having none, which is quite controversial right now.

You get a point for eating moderately, but you're supposed to cut back on meats and dairy. But even the dairy part is controversial. So as I find and I look through this, I see some of the scores count dairy against you, whereas some say, oh, yogurt is Mediterranean. And so what is the overarching idea of this, which I guess is a bit in the name, but help me to understand what is the sort of the concept of the Mediterranean diet? It really is a whole food plant-based flexitarian diet. So of all the names that you could give it, Mediterranean sounds kind of sexy. Ah, I love the temperate climate and I love all the foods from all those different cultures.

It certainly includes fish and it probably includes modest amounts of meat. But I actually, some of my favorite descriptions of the Mediterranean diet are the lifestyle that goes with it, which often doesn't get discussed. So in some of the older data where they recognize that people on a quote-unquote Mediterranean diet had better health outcomes, they were shepherds who walked miles each day tending their flocks. And they took a siesta every afternoon for three hours because it was hot. I would like to take a siesta every afternoon. I want a three-hour nap every day.

I'd settle for 30 minutes, Christopher. So really, if you go back, some of the original data were from the inhabitants of Crete who did this. And, you know, as time has gone on, it is one of the few diet patterns that actually has data. They've actually randomly assigned thousands of people to this and tracked them for years and years and saw that it saved lives, it saved hospital bills. Okay, so that's amazing because it's very rare in nutrition science, right, that there are studies that actually intervene, get people to change what they're eating and study this for long enough that you can sort of see long-term effects on like the end health conditions, like having a heart attack or stroke, because it's very, very hard. But you're saying in this case, there's actually that real hard data?

And I have an underlying reason for this. So it's fun. It's tasty. It's not low fat. It's got avocados and fatty fish and nuts and seeds. So I can imagine randomly assigning people to eat your usual diet or change to this Mediterranean diet, which a lot of restaurants will serve and sounds good, as opposed to, I need you to eat vegan or keto or some other restrictive diet where people aren't willing to sign up for that. Or if they are,

they're able to follow it for a short amount of time. And you made an excellent point there. There's a difference in these studies as to whether we're studying long term health outcomes or short term impacts on risk factors, which is actually what I do for a living. I study blood cholesterol, blood pressure, blood glucose, insulin. These are all things that you can change in your diet in weeks or months. But the real thing we're interested in is long-term health. And to study that, you have to follow it for years and years and years and years. Because you want to know, do people live for many more healthy years? So,

I guess by definition, you've got to wait for years to find out if that happens. What if you lowered your cholesterol, but died of misery or boredom or something, right? It's like, yay, I lowered my cholesterol, but I hate life. So Mediterranean is sort of indulgent. If you think of the things that come from the cultures that practice this so-called Mediterranean diet, but you are, you're right. I'm sure it's different in Morocco and France and Italy and Greece. It is not one diet, but it does have this theme. It's a whole food plant-based diet. So I think people listening will be like, okay, that sounds really interesting. I'm still completely confused about what it is. Maybe you could contrast it with, for example, like the typical American or British diet, which are quite similar. What's the difference between

that? If you were switching to a Mediterranean diet, which are quite similar. What's the difference between that? If you were switching to a Mediterranean diet, what would you be doing? So I actually think the best contrast is with this low-fat diet that has been so pervasive for so long. The Mediterranean diet, by the time you get the fatty fish and the avocados and the nuts and the seeds and olive oil poured liberally all over your salad is 40% fat or more. Okay, so it's quite a lot of fat in that diet. Quite a lot of fat. And in fact, we did this study of ketogenic versus Mediterranean diet, and it was a lot

of fun. We actually got the Mediterranean diet up to about 50% fat. And fat feels good in your mouth. It tastes good, but it's unsaturated fat. And so when we get back to that sort of misunderstanding of the low-fat message, it was always trying to get to low-saturated fat. Mediterranean diet is a low-saturated fat, high-unsaturated, whole-food, plant-based diet. So there's not much meat in the Mediterranean diet.

Yeah. When you look at the scores for Mediterranean diet, you get dinged for meat and livestock and processed meats and things like that. Yep. So it's again, not necessarily, as I understand it, completely excluding meat. You could eat a Mediterranean diet with some meat, but somehow this is the sort of once a week or something rather than the three times a day. Or it would be a smaller portion. So it's not a steak or a pork chop or roast beef at the center of the plate with some vegetables and starch on the side. So it's like a Mediterranean salad with Greek cheese on it,

or it's an eggplant moussaka, or I mean, this is just great, wonderful sounding names. And so you might actually be having meat quite a few times a week, but it's just sort of on the side rather than like a large piece of meat with a little bit around the side. It's one of the ingredients in here. So you've added some fish or you've added a small amount of lamb

or you've added some lamb. And so what else would be the difference as you shift from like this low-fat diet to a Mediterranean diet? Really the main focus for me is whole foods. Okay, I know whole food doesn't make any sense. So really what we mean is, yeah, those bakeries that you would have bread, where you would go to the bakery every day, you wouldn't get this white wonder bread that will last forever on the market because it would go bad. They sort of took out all the things that would have perished on the shelf,

so it'll stay there forever. No, no, no. This has some oils in it. This has some nuts and whole grains in it. Yeah, that would go bad and the bugs would eat them if you left them out on the shelf, because we expect you to buy this food and eat it soon. It's fresher. It is perishable. Yeah, and it really is just these cultures, you know, for centuries had those kinds of foods. They're just built on thousands of years of wisdom and they taste great and sound great. And you talked about sort of whole grain. Could you help people to understand a little bit? I think you've explained the fat side of this. What would it mean for sort of the sort of carbohydrates on your plate? Yeah. So especially in the U.S. for grains,

we eat mostly wheat and refined wheat. So what about millet and quinoa and barley and farro? And there's a whole lot of grains where you can make a grain-based salad or a grain-based dish, put vegetables and nuts and seeds and maybe some fish or some yogurt with it. So the whole grain would be not the flour that's all pulverized. It would be the, as it grew, as you were agriculturally growing this crop and you harvested it, eat the whole grain before you powderize it and grind it to a pulp. It's interesting. I was in Athens early in this year, which is where my co-founder George is from. And I was struck by a couple of things.

It's obviously definitely a heartland of the Mediterranean. First thing is sort of how many beans they eat as part of their sort of traditional dishes, which is something that in the States and the UK, we're really not used to. We've like really pushed it to the side. And the other thing is the enormous amount of olive oil that they put on everything. Yes. So yeah, very liberally putting on olive oil and other oils. So I don't want to overhype the olive oil. I think most oils are fine as long as you're not just drinking them, right? You're cooking with them and seasoning with them. The beans, I'd love to build on that. Beans are so underappreciated in the US. So many cultures have a diet based on grains and beans because

their storage capacity is really great. You dry the grains and the beans. They're packed with nutrients. They're packed with fiber. They're inexpensive as a whole. So they're really good at feeding populations that might not have all the resources for fancy food. So beans are very much underappreciated. And so many types types of beans kidneys and chickpeas and lentils and pulses like the overall name is legumes i don't know about in the uk but nobody in the u.s says legumes like nobody says like i mean like honestly i have no idea what legume is but legume is the overarching name that covers soybeans and peas and lentils and pulses and garbanzo beans, which technically, botanically are all different subcategories of legumes.

So Christopher, what happens in your body if you switch from this traditional US or UK diet to the Mediterranean diet and why are you seeing those benefits in your heart, for example, as a result? Well, I think the biggest deal, which honestly isn't played up that much, but it was in the study that we did of keto versus Mediterranean, we actually called it Mediterranean plus diet. Our main emphasis was getting rid of added sugars and refined grains. And that's in the US, that's 40% of our calories.

So here's some math that I would love to share on this question. So picture that 60% of your calories is some combination of three types of fat, saturated, mono, and poly, let's say 10 each. And then you're getting 10% of your calories, as they do in the U.S., from good carbohydrates, and 10 roughly from each of animal and plant protein. That adds up to 60. 40 left is added sugars and refined grain. So 40% of people's calorie intake is from like added sugar, just crap added on top of something else. Yeah, it's from crap. And so this is like ultra processed and... So as soon as you eliminate those 40% of calories, that would be a low carb diet because it was all carbs, refined grain and added sugars.

So this is the way I would love to frame it. So what if you replaced all of those with beans and veggies and plants? You would have a very low fat diet because you replaced the crappy carbs with good carbs. I don't, most people can't eat that many calories from beans and vegetables. It's very bulky. So you got the low carb people would say, oh, all of that should have been fat. Please move all 40%

over to fatty things. And that's pretty hard too, unless you're going to eat meat. That'd be a lot of avocados, a lot of nuts and seeds, a lot of fatty fish. And so what's going on inside your body when you make that shift that is actually delivering these health benefits? So I still think our major problem is too much simple carbohydrate that gets delivered too quickly to the bloodstream, which causes too much of a spike in insulin. So this is like blood sugar jumping in your... Blood sugar, monitoring these now with the continuous glucose monitors that I know Zoe has based a lot of their studies on, which is just fascinating that we're learning about the time sequence of what you're absorbing from your diet going into your blood

and being put away. And this Mediterranean diet, because it's fewer added sugars and refined grains and fewer carbs in total, because you've've got more fat is really going to slow all that down. So what are the possible challenges for someone saying, well, that's the first one, Christopher, that you sound like you quite like. What are the possible challenges with trying to adopt this diet? So it is a whole food diet and it requires some cooking. I know a lot of people don't cook, don't shop, order out. I will say there's lots of people making this. Like if you want to go out and find Mediterranean,

there's certainly plenty of restaurants and plenty of food delivery services that provide this. It takes more time to cook like that at home. It's easier to cook at home in some of these other ways. The downside with the Mediterranean is it's got enough flexibility that some people are going to be confused. Is this Mediterranean or not? I'm not sure if I'm doing the right thing. I read this recipe, so I don't think there's many downsides to it other than getting over-focused on olive oil or just not being sure exactly what meets that category.

I mean, one of the things that we see with, you know, sort of the thousands of people who are starting the Zoe members and starting on their program each week is that for many of them, it's complicated to understand how to go from what they're eating now, because people eat in so many different ways, right? If we were to just, you know, talk to everybody who's listening right now, there's this extraordinary diversity of the way that we all are used to eat. Understanding how to change and make steps for you to get to something much healthier is a lot harder with what you've just described, which I think for most people is quite close to the, you know, the core principles that they're likely to end up with than just saying, you know, cut out all fat or cut out all carbs, right?

That's like very simple. Count your calories. It's very simple. Whereas what you're describing, I think, is more complicated. And so I think there is a real challenge for people. And it's one of the reasons we do this podcast over a lot of time to help people to understand more about how they might adjust, you know,

many aspects of their life to improve their health. It's very consistent with a separate paper we wrote for ketogenic versus Mediterranean diet study. It was just on adherence, like how do we measure adherence? And we had constructed the Mediterranean diet to be similar to what a normal score would be, plus less added sugar and refined grains. We actually called it Mediterranean plus. And ketogenic, we had a well-formulated ketogenic diet. And so for some of these scores, the Mediterranean folks were doing not as well as the keto folks. And as we looked into this more closely, we said, ah, keto was just eating low carb. They got a lot of points for eating low carb. Mediterranean, they were supposed to hit higher fat, more legumes, more whole grains, more.

And we recognized pretty soon that that was a lot of categories they were supposed to hit every single day to be on this Mediterranean diet plus. So much to your point, yeah, there's many more goals and targets to hit at once so that as you're transitioning, yes, I nailed the beans one. Oh,

I forgot the whole grains. Yes, I nailed the olive oil, but I left this other one out. It would take time, which is fine. I think listeners should allow themselves some slack here and say, I'm learning about the olive oil. I'm learning about the beans. I'm learning about the whole grains. I don't have to do it all at once. I enjoy this. I enjoy that. I'm going to give myself months to figure out what this is. And I'm going to appreciate all the different options I have. And now I'm more comfortable with the whole packet.

It's not an easy thing that you can figure out for tomorrow. I totally agree. And I think I would just add, we were talking about this, you know, just before recording that it can be really hard if you're going shopping, you know, in the grocery store to understand what to buy, because so much of the food that we have today has all of these labels that these big manufacturers are putting on it, which, you know, basically are deceitful. Like they say in great big letters, you know, low fat, and they don't mention like all the things they've done to this food or, you know, how much of the food that is

on the shelves actually is, you know, very highly processed, ultra processed, but that's not very visible. And so it's, you know, I think quite hard for something like this diet that you're describing to figure out, okay, well, is this the ultra-processed, highly added sugars that you're describing, Christopher, or actually, is this the whole grain? Because there's a lot of things, sadly, that are pretending to be healthier than they are. True. Yeah. And I know shoppers want a simple thing. They'd like to be able to go to the store and say, on the label, I saw that sign, that symbol, and it meets my criteria. We don't have the Mediterranean diet symbol because there's so many different ways you could meet it.

And so, sorry, it's not as easy to identify until you adapt it and embrace it and enjoy it. Well, it's definitely something that I want us to be able to solve in the future. But I think that is, I think we should recognize one of the challenges. That's the challenge. So Christopher, what's your verdict on the Mediterranean diet? Double thumbs up. And again, you might misinterpret it and think it's just olive oil, but get past that and go ahead and take your afternoon siesta if you have the chance and go out and walk your

flock of sheep. But if you can't do that, go out for a walk because it's part of a Mediterranean lifestyle. It's like get outside, have some exercise, get enough sleep and eat well. Whole food, plant-based diet with enough room for some animal foods you could include or exclude. Brilliant. Well, I'm excited tomorrow to bring all of this together in our normal long form. I'm excited too. Thank you, Christopher. All right.

Thank you, Christopher, for our journey through the Mediterranean diet, part of our special series of daily episodes about diets and our health. I'm Jonathan Wolff. And I'm Christopher Gardner. Join us tomorrow for our regular weekly full-length episode of Zoe Science & Nutrition, where we'll be rounding up our analysis of diets and delivering our verdict on the healthiest diet to follow. As always, the Zoe Science & Nutrition podcast is not medical advice.

It's for general informational purposes only. See you next time.