The 5 best food swaps to lower cholesterol, protect your heart and to live longer | Dr. Alice Lichtenstein

Is fat good or bad for your heart? For decades, we blamed fat and cholesterol for clogged arteries and heart attacks. Now you choose low-fat yogurt to protect your heart, while others cook with beef tallow. In this episode, Dr. Alice Lichtenstein, a world-leading expert on dietary fat and heart health, helps settle the debate. Dr. Lichtenstein explains which fats protect your heart and which to cut back on, you'll learn what raises your cholesterol, and why the type of fat you eat matters more than how much of it you eat. You’ll leave the episode with some practical food swaps to protect your heart and live longer. Have you swapped butter for "low-fat" alternatives loaded with sugar? Could that choice be working against your heart? 🌱 Try our science-backed and tasty wholefood supplement Daily30 🌿Let your gut microbes snack on the ZOE Gut Health Bar Build healthy habits. Download the ZOE app today and start your trial for just £2.30 for your first week. 👉 Join ZOE Follow ZOE on Instagram. Timecodes 00:00 Intro 01:33 The most common myth about fat, busted in one word 03:20 What fat actually is, and why your body needs it to survive 11:29 Why butter and beef tallow turn solid at room temperature 13:12 How saturated fat raises your risk of heart disease 15:36 Heart attack or stroke: which one saturated fat actually raises 17:12 Are all saturated fats equally bad for you? 20:07 The flawed rabbit study that shaped decades of egg advice 21:41 What actually makes your cholesterol go up 24:04 How high cholesterol quietly clogs your arteries 27:04 The 1960s study that proved swapping fat saves lives 30:32 How your liver secretly turns sugar into fat 32:37 The verdict on beef tallow and butter 36:32 Simple food swaps for a heart-healthy diet 38:10 Does eating more fat make you gain weight? 40:35 The truth about grass-fed beef and omega-3 42:53 Is beef tallow really a healthy fat? 44:40 Is fermented dairy actually healthy? 45:19 The checklist to delay premature aging 47:52 The pantry check that could improve your heart health 49:56 The 1990s mistake we made with low-fat yogurt 51:47 Why knowing your cholesterol numbers matters most 📚Books by our ZOE Scientists The Food For Life Cookbook Every Body Should Know This by Dr Federica Amati The Appetite Reset by Dr Federica Amati Food For Life by Prof. Tim Spector Ferment by Prof. Tim Spector Good Mood Food (preorder) by Prof. Tim Spector Free resources from ZOE The Smart Snacking Guide: How to feed your gut, fuel your day, and snack without guilt The Hormone Harmony Guide: Tuning Your Body’s Internal Orchestra Eating for Better Brain Health: Your brain-gut blueprint How to eat in 2026 - Discover ZOE’s 8 nutrition principles for long-term health Live Healthier: Top 10 Tips From ZOE Science & Nutrition Gut Guide - For a Healthier Microbiome in Weeks Better Breakfast Guide Mentioned in today's episode Dietary trans fatty acids and cardiovascular disease risk, Current Atherosclerosis Reports (2014) Unsaturated fats, high-quality carbs lower risk of heart disease, American College of Cardiology (2015) Effect of Low-Carbohydrate and Low-Fat Diets on Coronary Heart Disease, JACC (2026) Rabbit models for the study of human atherosclerosis, Pharmacology & Therapeutics (2014) Have feedback or a topic you'd like us to cover? Let us know here. Episode transcripts are available here.

• 0:00Speaker 00

  Welcome to Zoe Science and Nutrition, where world-leading scientists explain how their research can improve your health.

• 0:14Speaker 00

  A ribeye steak marbled with fat hits a blazing pan. It crackles, spits and releases a rich smoky aroma that fills the kitchen. It hits the plate and the cook digs in with confidence, knowing he's eaten a whole food that his body's evolved to digest. Meanwhile, across town, his friend peels the full lid off a low-fat yoghurt, reassured that she's protecting her heart by avoiding fat. How did one nutrient become both villain and hero? How can we scroll through social media and find one person feasting on beef tallow while sipping butter-infused coffee, convinced that fat is the ultimate health food? Or another embraces the multitude of low-fat yogurts in the store?

• 0:58Speaker 00

  And more importantly, what should you be eating to protect your heart? Thankfully, there is an answer to this question. Today, I'm excited to be joined by Dr. Alice Lichtenstein, who's widely regarded as America's leading researcher on fats and their impact on health, especially the risk of heart disease. Having published hundreds of scientific papers, she's ranked in the top 500 female scientists in the world. Together, we're going back to basics, unpacking what fat actually is, why our body's needed and how what we eat influences our cholesterol levels and our risk of heart disease. For decades, fat has been blamed for clogged arteries and heart attacks. Yet, high-fat diets are booming and supermarkets are now lined with shelves promising to be fat-free

• 1:43Speaker 00

  and more shelves claiming to be fat-fuelled. No wonder we're confused. But by the end of this episode, you will have all the information you need to navigate this fat-filled maze. And you'll understand what Alice's latest research tells you to eat to avoid premature aging.

• 2:01Speaker 00

  Are there healthy fats we can eat to support heart health?

• 2:05Speaker 01

  Yes.

• 2:06Speaker 00

  If you removed all fat from your diet, would you die?

• 2:10Speaker 01

  Yes.

• 2:11Speaker 00

  Does grass-fed beef contain high levels of omega-3?

• 2:16Speaker 01

  No.

• 2:17Speaker 00

  If you have cholesterol in your blood, is that always a bad thing?

• 2:20Speaker 01

  No.

• 2:22Speaker 00

  The latest US guidelines say that beef tallow and butter are healthy fats. Do you agree?

• 2:27Speaker 01

  No.

• 2:29Speaker 00

  And finally, what is the most common myth that you hear about fat?

• 2:33Speaker 01

  If I eat fat, I'm going to get fat.

• 2:36Speaker 00

  And that's not true?

• 2:37Speaker 01

  No.

• 2:38Speaker 00

  Of everything we eat, I think fat has the most confused reputation when it comes to health in general and heart health in particular. Many of my relatives still refuse to eat food that they consider fatty because they're convinced that it will damage their heart, because their doctor has told them that their cholesterol is high or because they're convinced it's calorie-dense and so it's going to make them put on weight. And I have other relatives who swear that red meat is a natural whole food and so another burger must be great for their health. And so, given how confusing this topic is, I'd really like to start at the very beginning. What is fat?

• 3:20Speaker 01

  Fat is one of three macronutrients. There's fat, carbohydrate and protein. They're all made of carbon, hydrogen and oxygen. But protein also has nitrogen in it. What distinguishes fat from the other macronutrients is that it's what we call apolar. It does not mix with water. So you know, if you have vinegar and you have oil, you can shake it up, but then it'll separate. And that's because it essentially repels water. Therefore, our bodies have to handle it very differently than they handle carbohydrate and protein.

• 3:56Speaker 00

  And you mentioned that our bodies need fat. Why is that?

• 4:01Speaker 01

  Well, there's a whole class of compounds that we refer to as essential nutrients. They're given the designation of essential because our bodies can't make them. But they're essential for our wellbeing, for growth, for maintenance and for repair. And one of those essential nutrients is a fatty acid, linoleic acid. We can synthesise part of it, but we can't synthesise all of it. Therefore, for us, it's essential.

• 4:30Speaker 00

  What does it do inside us?

• 4:33Speaker 01

  Inside us, it is a very important component of things like our cell membranes. And all our cells have membranes, both external, that hold the cell together and then internal. And we also use it as what we call a precursor. We use it as a substance that we turn into something else. Our bodies can modify it. And that other compound has biological functions. So if we don't consume enough essential fatty acids, then there are going to be adverse repercussions because we don't have what the body needs to function adequately.

• 5:15Speaker 00

  And so, when I think about a food that has fat in it, do all of those foods have these essential fatty acids? Is all fat this essential fatty acid or is it more complicated than that?

• 5:27Speaker 01

  It's quite complicated, actually. The main essential fatty acid is linoleic acid. However, there's another one that's called linolenic acid. There's one that's called cosapentenoic acid, that's hexanoic acid. They're all relatively similar. The bottom line is we can't make them. They do occur in different foods. So linoleic acid and alpha-linolenic acid occur mostly in plant foods. So that would be oils that come from plants. Linolenic acid, which is a little bit different than the linoleic acid, is particularly high in soybean oil and canola oil. They're good sources.

• 6:08Speaker 01

  They're sometimes what we refer to as the plant source of omega-3 fatty acids. On the other hand, EPA and DHA are found predominantly in marine products. So that would be in fish and seafood. They too have unique properties. But again, what unites them all is they're essential for our bodies.

• 6:34Speaker 00

  What goes on? What does my body do when I eat something that's got lots of fat in it?

• 6:39Speaker 01

  Okay, well, the first thing is the body has to have a different system for handling it than the carbohydrate because it doesn't mix with water. And our GI system and our whole bodies are essentially solutions of water. So when we eat fat, we have a signal in our gastrointestinal system that results in the secretion of what we call bile acids into the mix of the food that we're eating. Those act as an emulsifier. Emulsifying means it allows the fat that we've eaten and all our digestive enzymes that are aqueous to mix. Then, as with carbohydrate, where it's broken down,

• 7:24Speaker 01

  the starch is broken down to individual glucose units. In the case of fat, most of the fat that we consume is in the form of triglyceride, which is one glycerol and three fatty acids esterified to it, attached to it. And then we have enzymes that can release those fatty acids. Then, once those fatty acids are released, they end up in a cell the same way that the glucose ends up in the cell. But for glucose, it gets into your blood system directly through the portal vein. For fatty acids, again, because they're fat soluble, they're only fat soluble. What we do is we actually package them within the cell into something we refer to as a chylomicron,

• 8:09Speaker 01

  otherwise referred to as a lipoprotein particle. And we actually secrete them, push them out into our lymphatics system, which then feeds into our blood system. So one of the big differences is with something like glucose, it goes directly to the liver and then the liver can either use it, store it or send it out to another tissue. With the fat we eat, it gets incorporated into the chylomicrons and then it actually circulates all over the place before it gets to the liver. And various cells have these enzymes on their surfaces that can pick off individual fatty acids from these chylomicron particles.

• 8:52Speaker 01

  So we handle it differently and that's essentially what happens. But eventually, it gets distributed to all the cells of our body.

• 8:59Speaker 00

  So the good news I'm listening to this is it sounds like my body also finds fats more complicated than carbs. So just like I struggle to understand them, it's like they're also just more difficult to deal with is sort of the picture that I'm understanding. Because they don't dissolve in water, I'm having to sort of wrap them in something to allow them to be transported around in my body?

• 9:16Speaker 01

  Yes, but not exactly difficult. We have beautiful systems to do it. So I don't think the body has any problem doing it. It's just that it takes a few more steps, but it occurs naturally.

• 9:30Speaker 00

  I guess my follow-on question, again, thinking a bit with that analogy with carbs, is the idea about is there such a thing as a good, healthy dietary fat? And like a bad dietary fat? Is it possible to eat too much of this too fast? So could you talk me through a little bit what we understand today? And I guess the thing that's in my mind is just saturated and unsaturated fat, but I don't understand what that means.

• 9:58Speaker 01

  Sure. Well, with fatty acids, we have a whole range of them, both in our bodies and in the food we eat. There are various ways of categorizing them. One has to do with whether they're saturated, monounsaturated, or polyunsaturated. Saturated means that the carbon atoms that make up these fatty acids essentially are just linked straight across to each other, so it's a long chain. When we get into unsaturated fatty acids, whether it's mono or polyunsaturated fatty

• 10:37Speaker 01

  acids, we have one or more of these carbon-carbon structures that actually have two linkages, not one linkage, and we call it an unsaturated fatty acid bond. When we have one of those, it actually causes what we refer to as a conformational change, a change in the way that the string of carbons lays out so that there's a kink, a bend in it. If the unsaturated fatty acid is a monounsaturated fatty acid, as the name implies, there's one double bond. If it's a polyunsaturated fatty acid, it means it's two or more double bonds, and

• 11:21Speaker 01

  it means that you might have a lot of kinks. Now, why is that important? And why are we concerned about the difference between saturated mono and polyunsaturated? Well, saturated fatty acids are these straight chains. So fats that are very high in saturated fatty acids would be something like butter and beef tallow and lard. Why are they solid at room temperature? Because the fatty acid chains are in straight lines, so it's easy for them to sort of pack together. Monounsaturated fatty acids, so you have the one double bond, it's sort of in the middle, and if you have experience with olive oil, olive oil is normally liquid. However, if you put it in the refrigerator, it becomes semi-solid.

• 12:06Speaker 01

  That's because the carbon strings can't quite align with each other because you've got that kink there. If you have a polyunsaturated fatty acid, and a lot of polyunsaturated fatty acids are in things like soybean oil and corn oil and fish oil, they can't align at all. So whether they're in a refrigerator or whether they're on a shelf, they're going to be liquid at room temperature. Now, in our bodies, we have these fatty acids that are also saturated, monounsaturated, polyunsaturated, that make up our cell membranes. There, we regulate it very carefully so that there's a certain amount of the fats, monos

• 12:51Speaker 01

  and polys, so that the fluidity of our cell membrane is where it should be. We don't want it too stiff, and we don't want it too wobbly. So we actually can preferentially take some of those polyunsaturated fatty acids, those essential ones, and incorporate it into the membrane to make sure that we maintain an optimal level of fluidity, but the idea is the same. It's because the structures are different, and it has to do with those little kinks from the double bonds. Now, they're trace amounts of all the fatty acids in all the fats we eat. However, as I implied, you can almost tell if the predominant class is saturated or

• 13:36Speaker 01

  unsaturated based on the physical appearance. So fats that are high in saturated fatty acids would be things like beef tallow, lamb fat, butter. The exception is what we refer to as tropical oils, coconut oil and palm oil. They're highly saturated, but they're liquid. Why? Because they happen to have really short chains of fatty acids, so they can't quite align as well.

• 14:07Speaker 00

  How do these different fats have an impact on our health?

• 14:13Speaker 01

  Okay. As far as our health, what we have found is that diets that are higher in saturated fatty acids raise LDL cholesterol. They result in higher LDL cholesterol compared to fats that are high in polyunsaturated fatty acids. That's important because the higher your LDL cholesterol, low-density lipoprotein cholesterol, the higher your risk for cardiovascular disease. Now, you may ask, well, why? Why do saturated fatty acids raise LDL cholesterol and unsaturated fatty acids lower it? We don't quite understand. There've been a number of what we call lipoprotein kinetic studies that try to look at the

• 14:54Speaker 01

  turnover of these lipoproteins, and it seems that they stay in the plasma longer when you consume more saturated fatty acids than unsaturated fatty acids.

• 15:07Speaker 00

  I think what you're saying is, if you're eating food that has saturated fat in it, and you're describing butter and the fat from like beef and lamb and things like this, but I think also coconut oil you mentioned, that you're going to have a higher level of LDL cholesterol, and that's the bad cholesterol in my blood, that's going to raise my risk of like a stroke or a heart attack or something like that?

• 15:32Speaker 01

  More heart attack than stroke. Stroke is more related to blood pressure.

• 15:34Speaker 00

  Okay, so raise my risk of heart attack, but I didn't understand why?

• 15:41Speaker 01

  Sure. Well, we don't understand it completely. What we do know is that your concentration of, let's say, LDL, the bad cholesterol, is determined by two factors. The rate of synthesis, you're making it, and the rate of degradation, pulling it out. And the balance with saturated fatty acids or diets that are high in saturated fatty acids tends more towards higher production and lower metabolism, whereas diets that are higher in polyunsaturated fatty acids, less production and more metabolism.

• 16:22Speaker 01

  It's not 100% clear because it's really hard to study that in a human being. But what we do know is that when we feed people diets that are high in polyunsaturated fatty acids and compare them to diets that are high in saturated fatty acids, their LDL is lower, and that's good.

• 16:40Speaker 00

  Now, I also understand from, you know, many of these conversations that there's been a sort of shift in nutrition science, was thinking more about the food than about sort of the nutrient within it. And so that within saturated fat, for example, you might have a slice of steak, you might have bacon, but you might also have like a dairy product, even a fermented dairy, and that those would be different examples, I think, of saturated fats. Do all saturated fats affect health in the same way? What is the latest?

• 17:14Speaker 01

  100% sure that they're all going to have, if those fats and consume more of the plant-based fats, it's more likely to be beneficial. So if we're not 100% sure, but there are some data to suggest that it might have a negative effect, and there are no data indicate that it would have an adverse effect, we're probably better off going towards the plant-based fats. And then in the plants, there tend to be this other whole group of compounds that are called phytochemicals, there are thousands of them. But we also, if we're eating diets that have more plants in it and fats from plants, we're probably getting more of those also.

• 17:57Speaker 00

  So I guess I'd love to talk a bit about cholesterol now, because that's the thing that we're all used to being told when we go and visit the doctor, like, I've measured this number. Most of us, as we get a bit older, the doctor starts to say, oh, this is getting a bit higher, or maybe I am worried about it. And they explain that this is also related to fats, so I think that makes, historically, the advice has been cut back, the fats, not just the saturated fats, but all of these fats. Could you start maybe by explaining what this cholesterol thing is?

• 18:32Speaker 01

  Cholesterol is a molecule, it's called esterol. It's just found in foods of animal origin. It is the same cholesterol that circulates in our blood that our healthcare provider tells us about. However, the amount of cholesterol we eat does not, for most people, determine how much cholesterol is circulating in the blood. Now, why is that? Number one, we need cholesterol. All our cells need cholesterol because it's also a critical component of cell membranes. So all our cells have the capacity to make cholesterol.

• 19:12Speaker 01

  Number two, we absorb between 40 to 60% of the cholesterol we consume if we do consume high cholesterol foods, plus we turn over the lining of our gastrointestinal tract about once every three days, and all those cells have cholesterol too that can be absorbed. So what the research has shown is that really has to do with the relative amount of unsaturated to saturated fat that determines our LDL cholesterol concentrations and not just the amount of cholesterol we eat. The historical thing is, in the turn of the 20th century, there were some studies done

• 19:52Speaker 01

  by some very good Russian investigators, and they studied rabbits, and they fed rabbits a lot of cholesterol, and sure enough, their blood cholesterol, that was the only thing they could measure, then went up, and they developed cardiovascular disease essentially in these rabbits. So it was just assumed the same thing would happen in humans. However, what wasn't taken into consideration is rabbits are herbivores. Their bodies can't control the amount of cholesterol they synthesize. When we consume a lot of cholesterol, our cells get a signal because the cholesterol then will go into a cell and it, we actually stop synthesizing. We really, it's called down regulation, the rate of cholesterol synthesis.

• 20:35Speaker 01

  So we, so for people who can maintain on their own a healthy LDL cholesterol level, it's because they actually can regulate how much comes in versus how much is synthesized. Unfortunately, a lot of us don't have that regulation.

• 20:50Speaker 00

  So I think what you're saying is in terms of the cholesterol that's in our blood, we don't need to worry about cholesterol in food. So that is something that we believed a long time ago. The science has moved on. We understand that's not true.

• 21:02Speaker 01

  Right, but we were tying it mostly to eggs. We just have to remember, and at least in the United States, a lot of eggs are consumed with bacon or sausage. That is a problem because that's where you're getting a lot of saturated fat.

• 21:19Speaker 00

  So it helped me to understand what does cause my cholesterol to go up?

• 21:24Speaker 01

  As far as dietary factors, the biggest one is the amount of saturated relative to unsaturated fat. It's not the total amount of fat, it's the type of fat. Then if we gain excess body weight, our cholesterol tends to go up. There are certain, very common genotypes that there, there's a family tendency for that to happen. We understand it has to do with the cells being less sensitive to the cholesterol that's in our blood to, to down regulate. But it really has to do with the quality of dietary fat. And there's a very interesting paper that came out two weeks ago and they actually looked at the high and low fat diets.

• 22:08Speaker 01

  And they looked at it on the basis of whether most of the fat was coming from animal sources, which would be more saturated fat, or plant sources, more unsaturated fat. And their conclusion was regardless of whether it's a high or low fat diet, it's the type of fat that matters, not the amount of fat.

• 22:26Speaker 00

  If I've been told I have high cholesterol by my doctor, the latest science does not say that you need to reduce the amount of fat that is in your diet. You just want to make sure that you're eating like healthy fats rather than unhealthy fats.

• 22:44Speaker 01

  Correct. And then you also don't have to worry about the cholesterol because cholesterol is only coming from the animal fat.

• 22:50Speaker 00

  So could I eat a diet that's really high in fats as long as they are healthy fats, even though I have a high cholesterol?

• 22:59Speaker 01

  If you achieve and maintain a healthy body weight. We have to leave room for protein and we have to leave room for carbohydrate because we get important nutrients from carbohydrate and fiber and we get important amino acids from the proteins. So it's not clear exactly how high you can push it, but just blanketly restricting fat, but consuming most of it from meat and butter, regardless of how much the total is, is not a good idea.

• 23:35Speaker 00

  What is it about this LDL cholesterol that is bad and means that I've got this risk of, of heart attacks?

• 23:42Speaker 01

  Okay, what's bad about it is that there's certain cells in the body, particularly in our blood system, our arterial system, that if the surface gets damaged, we have these cells that, they're called macrophages, that will gobble up LDL cholesterol. That if the LDL cholesterol is really high, they'll just keep catching it. Whereas under normal circumstances with other kinds of cells, as I indicated, if you've got a lot of cholesterol in the bloodstream, it'll go into the cell and the cell will turn off its endogenous cholesterol. But these macrophages actually don't, they just gobble it up and they lodge in the arterial wall.

• 24:25Speaker 01

  They ultimately actually get renamed to something that's called foam cells because they actually look foamy because they just gets, collect so much of this LDL cholesterol that they die. And that's what causes our fatty plaques.

• 24:42Speaker 00

  I've got this raised LDL cholesterol in my blood and what's happening is that my body is responding to this in some way. This is what you call these macrophages, these cells?

• 24:52Speaker 01

  Right.

• 24:53Speaker 00

  And they end up, you're saying, like trying to consume these?

• 24:57Speaker 01

  Absolutely, they're called scavengers. They just keep taking it up depending on how much is there until they die.

• 25:03Speaker 00

  And so you basically describe there's so much of this that basically these things sort of die and then they're stuck and accumulated and this then starting to effectively sort of block these arteries?

• 25:14Speaker 01

  Exactly, that narrows the arteries. So we have in our arteries, you know, we got lots of blood that's going through it. And particularly when it branches off, we, there are some, there's edging of this blood flow. And every so often, a couple of cells get knocked off from our lining and then they reform. But what happens is when you have really high LDL cholesterol and some of these cells get knocked off, it sort of allows these cells to work their way into the lining of the artery. And then those are the cells that are gobbling up all the cholesterol, dying, forming this

• 25:53Speaker 01

  stuff that looks like foam, eventually narrowing the artery and then setting you up for a heart attack. Or if it's the carotid artery, in that case it could be a stroke.

• 26:07Speaker 00

  So the very simplest level, if you've got high LDL cholesterol, this is bad news. Over time, this is going to sort of fur up your arteries. So you do want to avoid it. My realization, this is very complicated.

• 26:22Speaker 01

  Very.

• 26:22Speaker 00

  And I guess I would love to move a bit back from the complexity of the biology and a bit more about why did dietary fat, like the fat in the food we eat, become this incredibly feared macronutrient? When did that start?

• 26:42Speaker 01

  Well, the fat, so I told you about the carbohydrate, the fat really, we started hearing about that in the 1960s. So there was a theory that saturated fat, animal fat was associated with increased risk of cardiovascular disease. And then actually some of the studies were done in England, in London, where they took individuals who had had a cardiovascular event that were very high risk for having a second event, where they counseled people to reduce their saturated fat intake, mostly from animal products, replace it with soybean oil and a group that they didn't. Five, 10 years later, the group that replaced the animal fat with soybean oil had lower rates of cardiovascular events.

• 27:24Speaker 00

  So they actually had like fewer heart attacks if they swapped out?

• 27:27Speaker 01

  That's right.

• 27:27Speaker 00

  The meat for this plant based, you said it was a soybean oil?

• 27:31Speaker 01

  Mm-hmm. There are a few other studies that were done and they all showed the same thing, that if you replace saturated fat with unsaturated fat, there was a benefit in terms of what we call heart endpoints, essentially the cardiovascular disease events.

• 27:48Speaker 00

  What was happening is they were getting a lot of their fat from meat and red meat. And then the thing they were swapping to was generally still fat, but it was fats that were coming from plants.

• 28:02Speaker 01

  Yes.

• 28:02Speaker 00

  And in those cases, these studies showed really clearly that this was reducing the level of deaths and heart attacks.

• 28:11Speaker 01

  Then somehow in the nineties, people started getting into this thing about low fat. Well, if you have, eat a low fat diet, you're eating low saturated fat, so that's probably a good idea. And we saw in the 1990s, this suddenly fat phobia, everyone should be on a low fat diet. And what we also saw was this proliferation of fat-free foods that were really high in refined carbohydrate. So fat-free donuts, fat-free, ice cream, fat-free, cookies, all that. And even salad dressing that would have healthy fats, suddenly you could get a fat-free version. Somehow there was this misalignment that low fat meant low calories. You could eat all this stuff, wasn't the case. And that's why in 2000,

• 28:56Speaker 01

  Dietary Guidelines for Americans, the American Heart Association, I assume associations in other countries too, changed the guidelines from low fat to moderate fat, but still low in saturated fat. What was happening was, first of all, people in general knew that you shouldn't be eating a lot of cookies and brownies and ice cream and those things, but now they were all fat free, they were probably good for you and they were low calorie, they weren't. They started eating more, so suddenly the refined carbohydrate content of the diet went up and people's triglyceride levels went up. Now, why is that? There's something that's called carbohydrate-induced hyper triglyceridemia.

• 29:37Speaker 00

  You're going to have to explain that one day.

• 29:39Speaker 01

  I absolutely will. So you have carbohydrates and you break it down to glucose. Glucose goes into the bloodstream and normally we eat a certain amount and our different cells in the body take up the glucose, we use it for energy, we store it as glycogen, everything's good. However, when people have a really high level of carbohydrate intake, you have this incredible influx of glucose and it exceeds the capacity of the body to take it out of the blood. So it goes to the liver and the poor liver has to do something with it. And our liver is really very metabolically active. And what it does is it takes all this extra glucose, it can't store it because we don't

• 30:22Speaker 01

  have a large stirring capacity for glucose as glycogen, it turns it into fatty acids and it sends the fatty acids out into the bloodstream.

• 30:30Speaker 00

  So can I just make sure I've understood that? So I've now adjusted my diet, as I've been told, to eat all of these low-fat foods, which are suddenly all over the supermarket and which are now high in sugar and also sort of these refined carbohydrates that get turned into sugar. I eat them, I get all of the sugar in my blood and then you're saying my liver, which is really clever, just swaps that back into fat. So I've literally gone to all that hard work and I'm ending up with fat in my body, just like I would have done otherwise. Am I ending up with the good fats or the bad fats in this story?

• 31:03Speaker 01

  It doesn't matter if it's good fats or bad fats. Well, first of all, we can't synthesize our essential fatty acids, but what happens is the liver, it's synthesizing all these fatty acids from the glucose. It's got to get it out of the liver, it'll become sick, it'll become a fatty liver. So it puts it out on lipoprotein particles. Well, the lipoprotein particles that are high in triglyceride, that's what the fat gets turned into, fatty acid. And that increases your risk of cardiovascular disease.

• 31:31Speaker 00

  And so does that mean that therefore I don't need to worry about any of these, you know, heart attacks and things, like by not eating the fat, have I now avoided all the risk?

• 31:41Speaker 01

  No, no, because what happens is that liver's just made all that, those fatty acids that they've kicked out of the liver, you know, to keep the liver healthy, as triglycerides and they're on lipoprotein particles. And those lipoprotein particles then can get converted to LDL cholesterol. So no, you can't get around it that way, by just not eating fat. For most individuals, it would not be a good idea to consume a very low-fat diet unless you were really very vigilant about consuming high-quality carbohydrate.

• 32:14Speaker 00

  You were describing how there are all these studies in like the sixties showing that if you reduce the animal fats and swap to like plant fats, you got better, then in fact, the advice got people to switch from animal fats to this like low-fat. I'm coming back to your original question, you said beef tallow and butter are not healthy for us, am I saying that, are you?

• 32:38Speaker 01

  Yes, I would say that one should minimize intake of that, but instead of then choosing fat-free cookies, choose some kind of a plant oil. So cook with a plant's oil, use it to make salads, bake with it, those kinds of things.

• 32:56Speaker 00

  Do you have friends or family who are worried about high cholesterol levels, perhaps worried about the future of heart disease? If so, why not share this episode with them right now? So they understand what the latest science tells them about risks of heart disease, the importance of fats, and how to prevent premature aging. You might just help them live more healthy years. I would love maybe to talk now to understand this, maybe in a way that's getting a bit more practical for everybody listening. So maybe start with a big one. Is a low-fat or in fact a low-carb diet best for heart health?

• 33:35Speaker 01

  I would say it depends on what the choices are of the fats and the carbohydrates, that there's a lot of flexibility. And now we talk more about dietary patterns. It's not just the absolute amount of carbohydrate or fat, it's what your choices are within those categories, but then the whole picture. If you think about a dietary pattern, you say, okay, well dietary pattern definitely should have lots of fruits and vegetables. And it's nice to have a variety because different fruits and vegetables have different nutrients, but in reality, don't split hairs.

• 34:17Speaker 01

  If somebody really wants to eat iceberg lettuce and not romaine lettuce, go with it. You want to choose sources of carbohydrate that are made with whole grain as opposed to refined grain. It's relatively simple now. You can buy whole grain pasta, you can buy whole grain bread, brown rice, it's out there. It would be a good idea to get a lot of your protein from things like legumes and nuts. If you eat animal products, there's fish, pescetarians, dairy is an excellent, dairy products are an excellent source of high-quality protein. And if you're going to consume animal products, if you're going to consume meat, because

• 34:59Speaker 01

  that's what you want, then go for the leaner cuts. Watch the frequency, and this is where it comes down to the dietary pattern, the frequency and also the portion size. So most people can craft a dietary pattern, a healthy, what we call a heart-healthy dietary pattern, that will accommodate their personal preferences, their ethnic and religious backgrounds, and importantly, the availability and feasibility.

• 35:26Speaker 00

  I think that one of the things I've found, even just in my personal experience, is that a lot of people still really worry about the caloric density of fats. And so you're here saying like, there are some really high-quality fats and you haven't talked maybe as much about extra virgin olive oil as I was expecting, because people talk a lot about that on this show, but you know, just as an example, and you've talked about a whole bunch of other plant oils, people are still very worried, they're like, well, but it's got lots of calories in it, so if I eat lots of this, surely I'm going to put on weight.

• 36:06Speaker 01

  The data has not shown that there's really a one-to-one relationship with the absolute amount of fat in the diet and body weight. It really has to do with the whole package. Now, we're not talking about extremes, but if it's a little higher fat or lower in fat, people seem to adjust. I think plant oils are good. I think the best ones actually are soybean oil and canola oil, because they're also high in alpha-linolenic acid. Olive oil is a very good oil also, it's high in monos, it's not high in essential fatty acids, but if you prefer it, most of the time, I would say, well, have a few oils in the house and use them depending on what your preference is. So if you like olive oil in your salad, go for it. And if you're sauteing, then you know, you should consider maybe soybean oil or canola

• 36:51Speaker 01

  oil. And then of course, for a heart-healthy diet, in addition to lots of fruits and vegetables, whole grains over refined grains, plant sources of protein, fish, dairy, you want to watch the sodium and the added sugar, because those can have adverse effects on blood glucose levels, on blood pressure, and that will also contribute to cardiovascular disease. We talk mostly about cardiovascular disease, heart-healthy diets and the type of fat, but there are a lot of other factors that will modify it also. So if one thinks about the whole package, and there are various ways of accomplishing

• 37:31Speaker 01

  it, it may be, okay, now I know sort of what I should aim for. What am I eating, something in my pattern that I really think I could just sort of swap to make a healthier choice. I think if you think in those terms and then try it and see if it works, and then work on something else, and it may end up that you discover some things that you really enjoy. But I also think there's something else that's really important and I feel very strongly about that. And I think particularly in people that have, live in households with children, you're role modeling and you're really setting them up for developing dietary patterns that are going to be heart-healthy.

• 38:16Speaker 01

  One needs to think about that and for some people, that may be an incentive.

• 38:19Speaker 00

  So I'd love to maybe pick up on two food groups that are clearly quite controversial and discuss your thoughts about them. So on meat, why do a lot of people think that grass-fed beef is high in omega-3s, if it isn't? I'll never forget the moment that everything shifted for me. I was at a public talk on nutrition, listened to a speaker explain that my gut had trillions of microbes in it and that these bugs shaped every aspect of my health. That speaker was Professor Tim Spector, one of the world's top 100 scientists, who became my co-founder here at Zoe. Nine years later, Zoe runs the world's largest gut health research study, and the conclusion is simple. Gut health is health.

• 39:02Speaker 00

  How you feel, your long-term health and your digestion are all shaped by the state of your gut. As a listener to this show, you know how important it is to feed your good gut bugs, but I suspect that like me, you have a busy schedule and often you feel you haven't given them all the different plants they crave. And that's exactly why we created Daily 30. It's a gut health supplement packed with over 30 plants that you sprinkle onto any meal. It tastes great, adds a satisfying crunch and gives your gut the diversity it craves. Finally, a healthy, happy, that's easy to stick to. I should know, I take it every day. And because we're Zoe, we don't just guess, we test. We put our original Daily 30 formula through a randomized controlled trial, the gold standard of testing.

• 39:47Speaker 00

  The results blew us away and proved it supports your digestion, energy and gut health. That trial helped us develop the formula we have today. Today, Daily 30 is a non-negotiable daily habit for me. So don't put your health off for the future. Go to Zoe.com/daily30 and try it today.

• 40:05Speaker 01

  Because technically it is higher than grain-fed beef. However, they're both so low, it's an insignificant amount. It's one of those things that you can't just take it face value because you're going to lose. If anyone thinks that grass-fed beef has the same amount of omega-3 fatty acids as salmon, that's really unfortunate.

• 40:34Speaker 00

  And so if you do want to get omega-3s, where would you find them?

• 40:38Speaker 01

  The common oils that have omega-3s are soybean oil and canola oil, as I indicated. Flaxseed oil and flax, it's not something that we consume commonly, but that has a lot of omega-3. And again, it's alpha-linoleic acid. And then I think there's certain nuts. Then in terms of marine sources, it's what we refer to as the fatty fish. That's an unfortunate designation, but it's things like salmon or mackerel or bluefish. They tend to be the darker-fleshed fish. They tend to be the ocean fish. And as I mentioned earlier, the polyunsaturated fatty acids have these lots of curves

• 41:21Speaker 01

  and they stay very fluid at cold temperatures. Well, that's how those fish actually survive. It's that they're really high in those fatty acids and that's why they don't freeze down there. A chef once told me that salmon that's caught in the winter is actually here thinks it's a better quality than salmon caught in the summer because of that. Now, I don't have any verification on that, but seafood is an excellent source of omega-3 fatty acids. Any fish is probably better than no fish. So it's, and there is omega-3 fatty acids in other fish, it's just the higher ones tend to be those. If someone's not eating much fish, choose whatever fish you enjoy and enjoy it. The other thing is if someone, and this goes back to dietary patterns, if someone's consuming

• 42:05Speaker 01

  a lot of omega-3 fish, then they're probably not, for that entree, consuming a hamburger or a sirloin steak. So you're getting double benefit.

• 42:19Speaker 00

  I'd like to move on to beef fat or beef tallow, as it's called here, because it's definitely having a moment in terms of this idea that, well, cooking in beef tallow is healthy because it's a natural fat. But how strong is the evidence?

• 42:37Speaker 01

  I'm not aware that there's evidence that it's a healthy fat. I'm aware of the evidence that dietary patterns that are higher in beef and red meat and processed meat are associated with less favorable cardiovascular outcomes. It's not clear where this suddenly arose from, but I don't think right now it's adequately evidence-based that there's a real benefit and there may be a disadvantage avoided.

• 43:12Speaker 00

  And can I ask a follow-on question, which is wild game, like a deer or something like that, tends to have much lower levels of fat than the sort of animals that we, you know, eat, like a cow or lamb or something like that. And so in your opinion, to the best of just your judgment, is it the red meat that's bad for us or is it the fat in the red meat that's bad for us?

• 43:38Speaker 01

  I think it's the fat in the red meat. And if you had a cow that wasn't fattened up before slaughter or a pig that wasn't fattened up before slaughter, I mean, when you look at the way meat is graded, my understanding with red meat is if you have a very marbled piece, it's considered prime, the best. And it has to do with what you, what you're habitually eating.

• 44:06Speaker 00

  Can I talk about dairy now?

• 44:07Speaker 01

  Sure.

• 44:08Speaker 00

  Which I would say is much more controversial amongst nutrition scientists. And actually, just in these podcasts in the, in the last 24 hours, I've, I've had a couple of nutrition scientists say quite strongly that they think that particularly sort of fermented dairy, like yogurt, is, in their opinion, healthy.

• 44:31Speaker 01

  Fermentation, that's fine. It's probably good for the gut microbiome.

• 44:36Speaker 00

  I'd like to move on to something different now, actually, which is what should you do if you want to delay premature aging?

• 44:45Speaker 01

  Achieve and maintain a healthy body weight. Find out if you have elevated glucose levels. If you do, control it either with diet or drugs. Check out what your blood pressure is, if it's elevated. Control it with, by either restricting sodium or medication or whatever. Find out what your LDL cholesterol is and your HDL, your good cholesterol. We can modify our LDL cholesterol through diet and drugs. It's harder to modify your HDL cholesterol, the good cholesterol. Keep your numbers in healthy ranges. Obviously, you want to avoid smoking and exposure to tobacco products. You want to get adequate sleep.

• 45:28Speaker 01

  We're finding that is very important for healthy aging. And also easier said than done is, but managing stress. It's all one big package. I think there's no easy fix. What you want to do is adopt a healthy dietary pattern and mirror that also with physical activity as opposed to lying on the beach, go hiking in the mountains, something like that. But the thing is, you want to, if you want to live a long, healthy life, then you set yourself up early, you set your kids up early as far as healthy habits in terms of physical activity and diet.

• 46:07Speaker 00

  And I'm interested that one of the things you picked up there was this idea of checking where you are before you go elsewhere and that those things you were checking weren't super complicated, but you're saying like, know your blood sugar, know your blood pressure, know your HDL cholesterol. None of those things you can just tell about yourself, right? You actually do need to see a doctor, get a test to understand where you are. So you can't just say, oh, I feel fine.

• 46:33Speaker 01

  Exactly. That's exactly it. You don't know. And you should also listen to your clinician because if your clinician says to you, you know, you're getting older and your blood pressure, systolic blood pressure is going up, I really think it would be a good idea if you started taking medication. Listen to your clinician. Come back, make sure it's working, not too much, not too little. And it's, that's something that's probably going to be lifelong. You don't cure hypertension, but you can control it. And the same thing with LDL cholesterol and with glucose.

• 47:08Speaker 00

  Final question. If you could give our listeners one piece of advice on what to do to improve their heart health that they could sort of start tomorrow with, what would it be?

• 47:18Speaker 01

  I think it would be sitting down and taking a real hard look at if they get most of their food at home, what's actually in their pantry and in their refrigerator, and if they get most of their food outside the home. And, and think about, now that they know what a heart-healthy diet, a dietary pattern is, they think about dietary patterns, think about their personal preferences, where can they make changes? Where can they shift to make it healthier? And then it's a matter of as they replace food in their pantry and in their freezer and refrigerator, the more healthy choices. It's more likely that you're going to eat what's available.

• 47:58Speaker 01

  I think also the consumer has a lot of power, is more people, let's say, shift to buying more, and we've seen it with, let's say, with pasta, whole grain pasta, you see more whole grain pasta. But, but I do think on an individual level, it's just really taking a serious look at what their patterns are and really honestly deciding what they can do to shift it, to make it healthier.

• 48:22Speaker 00

  Wonderful. Thank you so much. I'd like to do a little summary and share maybe the key things that I've taken away from this. I mean, the first and most obvious is that fat has been really demonized over the last 40 or so years. And not only is that unreasonable, actually, like, we would die if we weren't getting this essential fat. So like, you need to have fat in your diet. And interestingly, it seems like we've known even back from the 60s that if you reduced your consumption of these animal fats, that actually reduced your levels of like heart attacks and risk of death.

• 49:03Speaker 00

  But in those cases, they weren't swapping towards a low-fat and high-carb diet. Actually, in those studies, they were swapping to plant-based fats. And so interestingly, like, we've got half of this right, which is like eating this diet that was very heavy in animal fats and, you know, and the butters and the beef tallow that we talked about and the steaks was good. But then we made the horrible mistake of saying, oh, so you should eat, you know, low-fat yogurt, as we would say here. And actually, that is not what the science showed. And now, as we jump forward to today, we can see we've had this epidemic of obesity and all these other health problems. And so trying to push down fat was a mistake.

• 49:48Speaker 00

  And the right message really was more about how do you increase the healthy fats in your diet? And you've talked about the oils that we would like to have in our diet, whether that's like canola, which is rape seed in Europe, or soybean. You've also talked about the benefits of sort of oily fish, all these things that have omega-3s in them. And you explained how essential this is for our body, down to the fact, like, every one of our cells needs these fats. That the story that we're used to getting when we visit our doctor, which is, well, hang on a minute, your LDL cholesterol is high, you need to do something about it. Well, that part is right. You said that one of the key things is to have that measurement and know what it is, but that what you don't want to do as a result is say, oh, okay, so I'm not going to eat

• 50:32Speaker 00

  any fat, I'm going to go and eat all these carbs. Because what you said is, well, actually, you know what? If you just eat lots and lots of these, like, refined carbohydrates, you'll get too much blood sugar in your blood. And magically, your very clever liver is going to say, well, I haven't got enough fat and I've got too much blood sugar. And it just turns into fat in your blood.

• 50:49Speaker 01

  It's not that it doesn't have enough, it's just it's overwhelmed with glucose and it's the only thing it can do.

• 50:54Speaker 00

  You can't avoid it. Your body is sort of swapping between these and that critically, fat is not bad. We need to understand the sources. Your advice, I think, overall about what we should eat is very much think, well, someone would think about is sort of like the Mediterranean diet, lots of fruits and vegetables, lots of whole grains. I think the other thing that I took away was, you know, if you want to avoid premature aging and make sure that you actually live like the sort of the longest, healthiest life that you can, then clearly thinking about heart disease is a really important part of that. And what you were saying critically is like, sort of be aware of your own numbers.

• 51:35Speaker 00

  And this is sort of like knowing what your blood sugar is, knowing your blood pressure, knowing what that LDL cholesterol number is, because that's in guiding you like, where am I and what do I need to do? And then if you're putting around this like good diet and exercise, then you're able to have probably very big impact on those final numbers.

• 51:54Speaker 01

  Exactly. Well done.

• 51:57Speaker 00

  As you can imagine, hosting this podcast, running Zoe, juggling family life, it all keeps me pretty busy. So I try as best I can to stay energized and show up well in all those parts of my life by fueling my body with the right food, by exercising and by adding a scoop of Daily 30 to my meals every day. If you haven't heard of Daily 30 yet, it's the gut supplement designed by our gut health scientists here at Zoe. It's made of over 30 high-quality, hand-picked plants, including seaweed, fungi, and different types of fibre. Better yet, it contains ingredients to support gut health, digestion, and energy, which is ideal for packed calendars and busy lives. Simply add one scoop a day

• 52:42Speaker 00

  to any meal for an extra boost of fibre and plant diversity. And because it tastes delicious on just about anything and adds a satisfying crunch, it quite quickly slots into your life, becoming a daily healthy habit you'll always have time for. By the way, whenever we talk about Daily 30 as a good source of fibre, we're required to say that it contains four grams of total fat per serving. Obviously, that's all amazing, healthy fats from plants. So order yours today at Zoe.com/daily30. Thanks for listening and see you next time.