How to lower cholesterol in 10 days | Prof. Sarah Berry
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Welcome to ZOE Science and Nutrition, where world-leading scientists explain how their research can improve your health. Today, we're talking all about cholesterol, what it is, how it works, and how to keep your levels healthy. Nearly 40% of people have high cholesterol, a condition that causes fatty deposits to build up in your arteries, increasing your risk of heart attack and stroke. It's really no wonder that many of us fear cholesterol.

But many of us fear it without actually understanding what cholesterol is or how it works. And recent data shows that the way we process cholesterol may differ from person to person. On top of all that, not all cholesterol is actually bad. Today, Zoe's chief scientist is here to explain. Dr. Sarah Berry is a world leader in large-scale human nutritional studies, associate professor in nutrition at King's College London and chief scientist at Zoe.

One of her main areas of research is diet and cardiovascular disease with a focus on blood lipids like cholesterol. And in this episode, she explains the best ways to lower bad cholesterol and raise good cholesterol to improve our health. Sarah, thanks for joining me today. Pleasure. Thanks for having me back. Always wonderful. And this one I think is going to be really fascinating because we get so many questions about it. It's quite complicated and I know you're going to walk us through it.

To start with, are you ready for the quickfire round of questions? I'm ready and raring to go, Jonathan, on this one. Let's jump straight in. Is all cholesterol bad? No. Do we need cholesterol to survive? Yes. Could too much bad cholesterol put me at risk for heart disease? Yes. Can the composition of your gut microbiome affect cholesterol levels? Yes.

Could the right diet improve your cholesterol as much as medication? Yes. And I know how cautious you are, so I'm impressed with that. What's the most surprising thing, do you think, about cholesterol? So I'm going to be greedy, Jonathan, and ask for two surprises here. So the first surprise is that following a high healthy fat diet can actually improve your cholesterol. And the second surprise is that following a high carbohydrate diet can actually make your cholesterol worse.

When the podcast team told me before the show how many people struggle with high cholesterol, I was shocked. Apparently that's 40% of people in the US and the UK, which is an incredibly high number. And I think people who've listened to the podcast often know that, like I have my own story about this, that my father was diagnosed with high cholesterol when he was very young. We were in the States, so it was a long time ago now. And as a result,

he was asked to go on this very low fat, very high carbohydrate diet. And it's interesting hearing what you say, because that's sort of almost the opposite of what you were saying. He was told because of this high cholesterol, he mustn't eat any fats and he should eat as many carbohydrates as possible. So I know that for him, it's had a big impact on how he eats. And I think for many, many listeners, this is one of the things about

their health that they first get this indication about from visiting a doctor, really feel like they have to go and change this diet. They tend to get this very specific advice still, in many cases, to reduce fat. A lot of people are really interested, but it's also really confusing. There's different sorts of cholesterol, which I can never remember. And we're all being told we should lower it, but it feels like the advice is...

It all feels like contradictory. Are you going to be able to like step us through this and give us some clarity? I'm going to try and step you through this, Jonathan. I normally spend several hours teaching this to our students. So I'm going to try and condense it as much as I can. Amazing. Well, could you just start at the beginning? What is cholesterol?

So cholesterol is a type of lipid. So it's a type of fat that circulates in our blood and that we can also eat as well. And it's a waxy kind of substance. And it's something that's actually necessary for us. It plays a really important role in our body. So we need it to make many different hormones. We need it to make vitamin D. We need it to make bile acids that are essential for the absorption of fat.

And actually, it's a component of every cell membrane in our body. Every single cell has this. Yes, has cholesterol. So without cholesterol, we would be in a little bit of trouble. And so if I understand, in fact, total, like we have to have it, we wouldn't live without it. Yeah. And that's why our body makes it. You know, our bodies are so clever. So we don't make things that are bad for us just for the fun of it.

it's where these natural processes become a little bit disbalanced. It's just where the problem comes in. But cholesterol is an essential part of our normal physiological functioning. And when we often hear about cholesterol, we also hear about it being in food we can eat. Is that the same cholesterol or is that something different? So it's slightly different, but more importantly, the way it impacts

our health is very, very different. And so what we know is that dietary cholesterol, so the cholesterol that we eat, that is found in many foods, but for example, we might think of some foods as being very high, like eggs, actually has very minimal impact on the cholesterol that circulates in our blood. Got it. So it's not just the cholesterol in my blood is a result of the food that I eat. No.

So if cholesterol is necessary and it's floating around inside our bodies, I guess my obvious question is what's it doing in our blood? Because that's where I think the doctors are measuring it and getting concerned. And why is some of it considered bad?

Yeah, so we know that there's some type of cholesterol, which we call LDL cholesterol, is bad for us. And we know there's some type of cholesterol, which we call HDL cholesterol, is good for us. But as always, Jonathan, it's not quite so simple as that.

When we talk about LDL cholesterol and HDL cholesterol, we're actually talking about the packages that the cholesterol is in. So LDL cholesterol stands for low-density lipoprotein. So that's the kind of package that it's in. It's the parcel that it's in. HDL cholesterol basically refers to cholesterol that's packaged in a high-density lipoprotein parcel. So you've got these two different parcels, but they actually contain the same type of cholesterol, but it's how they're packaged.

And where it becomes really interesting is the label. So the address label that's put on these packages is where actually it becomes really interesting in relation to disease. So how does this fit with what we eat?

Because, you know, one thing I would have thought listening to this is, well, if I'm worried about my cholesterol, I just won't eat any fat. So I can't have any fat in my body. So I'm going to be really healthy. But you just said in the beginning, actually, if you eat certain sort of fats, your cholesterol might get better. And you also said if you didn't eat any fat and you just ate carbs, it could get worse. So...

How does that fit with this good and bad cholesterol? So this is one of the big myths that actually cutting out your fat reduces your cholesterol. It's nonsense. And the fact that it's still a myth out there is really blimmin' irritating. So let's debunk that. What we want to do is we want to reduce our LDL cholesterol. We want to reduce the cholesterol that's circulating in these bad particles.

What we want to ideally do is increase our HDL cholesterol, so the cholesterol that's circulating in these good particles. And the reason we want to do that, very simply put, is because the cholesterol that's packaged in LDL is the cholesterol that is circulating in our blood and delivered to our peripheral tissues. It's delivered along our arteries where it can be actually taken up into the arterial wall. The LDL particles have a particular label on them

which is called the apolipoprotein B label. So it's got like this address label saying that the receptors on the lining of our blood vessels recognize that enables it to cross over into the lining of our blood vessels because of this address label as a way of describing it called apolipoprotein B. It's then taken up by the lining of the blood vessels over time.

This causes this atherosclerosis, so this furring, which causes the narrowing of the blood vessels. And over time, you can get plaque formation. These can become unstable. These can then burst. And that's when you get a blockage, which causes a heart attack. So that's clearly bad. You definitely don't want that. And that's all coming back to this amount of LDL in our bloods?

Yes, so it's about how much LDL there is circulating in our blood, how long it's circulating in our blood. The really good news is that diet can have a huge impact on the amount and the duration that LDL is circulating. It can impact how much LDL we're producing. It can impact how quickly we actually take LDL and remove it from the circulation as well.

I definitely want to get into that for certain. And so we're definitely going to talk about actionable ways you can do this. Before we get there,

Could you talk a bit about the HDL as well? Because I know that when I see my doctor, he talks about the HDL being good and so a high number somehow being positive. It's not just this LDL number that he's at least telling me that I should worry about. Yeah, so that's correct. So HDL is the particle that carries the cholesterol away from the periphery, away from our blood vessels.

back to our liver. So quite a simple explanation, but I think it's the best way to explain it. So you've got LDL that's basically taking the cholesterol and putting it where we don't want to put it. It's delivering that parcel to the wrong address. And then you've got the HDL, then re-delivering it back to the right address. And so that's...

effectively sort of putting a label on it, you're saying in our blood, so it's going to go back to its original point in the liver and get it out of the bloodstream because there's more than you need? Yes, in simple terms, yes, that's what it's doing. So we often talk about it in terms of reverse cholesterol transport, that it's taking it back.

What we know though now is that the focus that we had five, 10 years ago on increasing our HDL cholesterol, that there's many nuances to this about kind of the sorts of particles the HDL is circulating in, the size of these particles and lots of other things that I don't want to kind of get too technical on today.

But the summary of that is that we know now that whilst, yes, we do want high levels of HDL cholesterol, actually what's far more important is to focus on our levels of LDL cholesterol. And so if we have high levels of LDL cholesterol...

and have high levels of HDL cholesterol, we shouldn't be complacent thinking, oh, it's fine because my HDL is high. Actually, what's really important is to bring that LDL cholesterol level down. We know that for every one millimole increase in LDL cholesterol, you significantly increase your risk of cardiovascular disease over 10 years by about 25%. 25% is obviously a huge increase in risk.

Can you help me to understand how the food fits into this story? Because I was definitely brought up as a child with this idea that your cholesterol was high because you'd eat an egg that had lots of cholesterol in it. And I know we've done a podcast on that. You said that's not true. When you eat the egg, you break it down. But-

You've also said that when you eat fat, that fat does go into your blood. So how does that fit into this story of LDL? And I think, again, the sort of really amazing answer to your quickfire question saying that you could actually eat some fats that would reduce your cholesterol, which sounds...

crazy. Help us to understand. Okay. So I think I'd first like to spend a minute just setting the record straight on dietary cholesterol. We have done a podcast, I know, on this before, but just to summarize for people who haven't listened to that, we now know that dietary cholesterol, so the cholesterol that's in our food, for example, eggs, does not increase our circulating level of cholesterol. And

Obviously, I always have to caveat this, Jonathan. If you're consuming 30 eggs a day, then it will have an impact. But at normal, typical levels of intake, dietary cholesterol does not negatively impact our circulating cholesterol. Most people are getting less than 300 milligrams of cholesterol a day. And below that, it's not going to have any meaningful impact. So you can have one to two eggs a day and not impact your cholesterol. What does impact our cholesterol?

is actually not dietary cholesterol, but it's other dietary components. The biggest dietary component that impacts our cholesterol is fat, but not in the way that you think. It can actually have a huge favorable effect on our cholesterol. A favorable effect on our cholesterol. Yes. If you were to say to me, Jonathan, how should I reduce my cholesterol level? I would start by saying, start eating fat. But I would say start eating the right type of fat.

So I'm guessing you're not going to tell me that I should just eat ice cream and butter.

No, I'm sorry. Or cakes or lots of other things. So we know that there's lots of different foods, nutrients that can impact our cholesterol. And I think there's a kind of dietary pattern that has been studied quite a lot called the portfolio diet. And I often use this as a really nice way of explaining how powerful diet can be in impacting cholesterol.

cholesterol levels and most importantly those LDL cholesterol levels because I really want us to focus on those rather than so much on the HDL given how strongly linked LDL cholesterol is with cardiovascular disease. So the portfolio diet is a portfolio of different dietary components.

It includes having phytosterols, we can pick up on this. It includes having soluble fiber like beta-glucans. It includes having plant-based proteins and it also includes having nuts and seeds. So it's those four main components.

And this is largely because the effect that those components have on how we process cholesterol and how we also remove cholesterol from the circulation. But the single most potent effect that we can have is by increasing our dietary fat intake to increase the amount of polyunsaturated fatty acids that we include in our diet. If we combine all of those four components that I've just said from the portfolio diet, you can actually reduce your cholesterol immensely.

by about 30%. That's huge. That's the kind of level of reduction that you'd get from a statin. Now, to follow the portfolio diet is quite difficult. To have the right amounts of all of these different components is quite challenging from a normal diet. And this is why I think dietary fat is a really nice, simple, single strategy that we can implement to reduce our cholesterol. Hi, I have a small favour to ask.

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I just want to make sure I've taken away the takeaway here, which is that by increasing the right fats that you eat, you can actually lower your cholesterol levels. Yes. So I think the takeaway here is that there's multiple different ways we can reduce our cholesterol. There's multiple different foods and multiple different nutrients.

And one of the components of the portfolio diet and one of the key single strategies, in addition, is to increase the amount of fat we're having from healthy fat sources. And that can significantly reduce our bad LDL cholesterol. And Sarah, why is it that people have higher levels of LDL? So, you know, if we all start at really healthy levels, because you're saying we have to have some, you're describing, in order to live, like what is it that means that

Living, you know, in developed countries, it seems as though that's just sort of standard. You sort of expect many, many people, like 40% we talked about earlier, getting these test results saying it's too high. What's going on there? So there's lots of different reasons and it varies from one person to the next person. So we know that there are some genetic components to this.

We know that there's some quite serious genetic components such as familial hypercholesterolemia where people can have cholesterol from birth very high, you know, in the region of, you know, for example, 12 millimoles per litre. These people often less treated will not live into adulthood. Fortunately, they can be treated with statins and so it's not so much of a problem now.

We also know that there's lots of other small genetic variations that can impact how efficient we are at removing cholesterol. And a really key component of this is the LDL receptor. The LDL receptor is a receptor that sits on our liver and it's what removes the cholesterol from circulation for it to be recycled for different uses.

And so many of the reasons that some people, compared to other people, have high cholesterol is because they might have slight changes in how this LDL receptor is working. And it's also the reason why diet can have an impact on LDL cholesterol, because it can impact the LDL receptor. So we've got genetic components, we've got dietary components.

mainly act through the LDL receptor, but also some other areas. But we also know that lifestyle can impact our cholesterol levels. So we know, for example, excessive alcohol. We know that living with obesity can also impact as well. We know that inactivity can also impact cholesterol levels. So are they higher now than they would have been a few hundred years ago? That's a tricky one to answer because

we are so good at measuring cholesterol now. So people over a certain age will have regular lipid panel tests, which measures cholesterol along with some other blood lipids. And people are put onto statins, which we know are very effective at lowering cholesterol if it's above a certain level. So because of that, cholesterol is kept in check.

But we know that cholesterol in terms of how it's increased by diet is more of a problem now because we are consuming a kind of diet that is not favorable for our cholesterol. So you're saying the diet is making it worse. But on the other hand, there's this huge number of people on statins, which are sort of keeping it under control. Absolutely.

And you answered a question early on that I'd love to come back to about the gut microbiome. Is there any evidence that that is linked to cholesterol? Yeah. So we have evidence from our own Zoe Predict studies. And there's a paper that we published in Nature Medicine in 2021 where we looked in our Zoe Predict 1 study at 1,000 individuals.

And we found a very close association with the microbiome composition and the different levels of cholesterol. And we saw that specific species could actually be quite predictive of our cholesterol levels, whether it be our LDL cholesterol, our HDL cholesterol, but also many other hundreds of

lipoprotein particles are circulating that for someone like myself that studied lipids for ages is incredibly exciting. I won't bore you with it. We also see different species associated differentially with that. So we actually developed a microbiome signature and this signature clearly separates lipids

that are associated with favourable measures of cholesterol, so i.e. higher HDL, lower LDL, and some of these other particles, and then ones that are associated with unfavourable measures of cholesterol. There's also randomised control trials where people are given probiotics, for example, probiotic supplements, and you see that not always, but most of the time, these probiotics can lower cholesterol as well. And we also are starting to understand some of the mechanisms involved

It's not fully understood yet, but we know that there's particular chemicals that are produced and particular enzymes that are produced by gut bacteria that impact how we metabolize cholesterol.

I'm thinking, do I risk it? And I'm going to go for it. I'm going to push one level more complicated here because I know that as well as this LDL and HDL measure that we've talked about, that there are a number of other measures that you're really interested in and that you talk a lot about when you're doing your own studies and looking at other studies. Can I start with this one called APOB, which I know is starting to be used, I understand, in some clinical tests, but it's not generally the first thing you get from a physician.

Is it real? Does it matter? What's the difference between that and this LDR? Okay, it's real. It matters. But I need to give you a little bit of a physiology lesson to explain why. Go for it. Okay, so what happens when we eat fat? When we eat fat, it's packaged into special parcels. We call these lipoprotein particles. And it gets given a label. It gets given a label called ApoB.

Okay. We also produce fat by our liver. So the fat that circulates in our blood doesn't just come from the fat that we eat. Our liver is continuously producing fat. When the liver produces fat, it also packages it into these nice particles called lipoproteins, and it also gets a stamp label on it called apolipoprotein B.

So what happens is, is you have circulating in your blood, whether you're fasted or whether you've just eaten loads of these particles that have an address label on it called apolipoprotein B. Okay. These at the beginning tend to be really rich in triglycerides. So triglycerides are the main source of dietary fat. They're the main way that fat is produced in the liver.

What happens is, as it circulates in your blood, gradually you remove the triglycerides from these lipoprotein particles with the ApoB label. And you remove them because, you know, your muscles want them for energy, you know, etc. What you end up with is you end up with quite a small particle that's still got the ApoB address label on it, but it becomes very cholesterol rich and doesn't have much triglycerides.

And that is the LDL, the low density lipoprotein particle, because it's tiny. That's why it's called low density. It's a low density particle and it's got that ApoB label on it. We know that all of those lipoproteins that have this address label called ApoB on aren't very good for us. Okay. The reason they're not very good for us is because it's the ApoB

So it's the address label that actually our blood vessels recognize. It's not the cholesterol in the LDL, it's the label. So that's why I refer to it at the beginning as kind of the address label. So the ApoB is the address label saying, hey, please take me to the blood vessels so that I can enter the blood vessels safely.

fur them up and cause you a bit of a problem. That's the byproduct of them sort of hanging around for too long? Yes. So if we're eating a healthy diet, then what's happening is our LDL receptor is, you know, happy as anything and it's removing these apolipoprotein B particles.

And that's happening in your liver? So they're on the surface of the liver, yes. And it's removing these apolipoprotein B particles in a timely manner. However, if it's not working very well, which could be, like I said, through genetics, through poor diet or poor lifestyle, then these apolipoprotein B particles are sticking around for a lot longer. When they stick around for a lot longer, they're in the form mainly of the LDL.

apolipoprotein B particles. So that's why we can think of LDL cholesterol as a proxy for apolipoprotein B. The more direct risk is actually the amount of this ApoB that you have. And so measuring the ApoB directly would be more accurate measure of sort of your risks than the LDL? Correct. So why don't we just all measure ApoB when we see the doctor? It's more expensive and it's harder to do. It involves quite specialist...

So I measure apolipoprotein B in my research. In fact, I measure the 200 different types of lipoproteins that can circulate, which I would love to tell you about all of them, but you're going to fall asleep within a minute. And they all tell us something slightly different. But the apolipoprotein B is, we know, the single most important protein

of cardiovascular disease in relation to cholesterol. But LDL is very cheap, very simple, very quick and easy to measure. Every hospital lab can measure it in minutes. That's why most people have LDL measured. It's still really important. We mustn't lose sight of the fact that actually LDL cholesterol is a problem. It's just that in an ideal world, Jess would measure ApoB. And I know that people are increasingly talking about ApoB. But

But most of the evidence that we have out there shows, you know, as long as you're measuring or trying to reduce LDL,

Because if you had a high LDL, you're likely to have a higher ApoB in two. So they're like different measures, but they're pointing in the same direction. This is just a more accurate one, which is why you've convinced us to measure it on many, many thousands of people doing ZOE in the next year as part of this big new study. That is why we're measuring on thousands of people to look at how following the ZOE program impacts the

whole host of different health measures. And ApoB is one of the ones that I know, you know, it is a lot more expensive for us to do it. We're doing it as part of our research, but it's because I believe that it tells us that little bit more and gives us more insight. But we're also measuring, Jonathan, about 30 other lipoproteins as well. There are probably like 100,000 or more listeners right now who are saying,

Hang on, Sarah, help me to understand what happened when I did my initial test when I became a member of Zoe. And you talk about something called triglycerides and you measure it over time. How does that fit into this story, which I think for most people is really saying, I'm worried about my cholesterol and I'm worried about what I should eat?

Okay, so let's step back to that physiology lesson I gave you about five minutes ago. And if you remember, I said when you eat dietary fat, you eat it in the form of triglycerides and it gets packaged into these lipoproteins. They get the ApoB address label put on them and then circulate in our blood. The triglycerides are slowly removed and you end up with this LDL ApoB parcel. And so just to check, you know, if I, so if I eat a piece of cheese, you're saying that

Once I chew that and swallow, it goes into my blood as something called bits of triglyceride. Yes. So when you...

Eat food and you eat fat. 98% of the fat that you're eating is in the form of triglycerides. The other 2% is in the form of cholesterol, phospholipids. But the dietary fat is basically triglycerides. It's also triglycerides that the liver is constantly making that are also packaged into these proteins.

proteins. What we know is that as well as the amount of circulating LDL cholesterol in your blood, we also know how much triglyceride is circulating is quite important. Now, the liver is constantly producing triglycerides and you can measure that in a fasting triglyceride measure. So when you go to the doctor and have a standard lipid panel, you'll have a measure of your total cholesterol, HDL, LDL cholesterol, and also triglycerides.

But what we now know is that the extent to which your triglycerides increase after you have a high fat meal is also important in terms of your disease risk.

So what happens when you eat a high-fat meal, you have an increase in circulating triglycerides because the fat in the meal are triglycerides. So it increases the triglycerides that are circulating. They peak about four hours to five hours after you've had the meal, and then they return to baseline about eight hours. Considering we consume many meals over the day, you actually spend very little of your time in this fasted state.

given that it takes about eight hours to clear the fat. So one of the things that we look at when we're looking at blood fat control with our ZOE test in

In addition to looking at LDL cholesterol, which we look at as part of this test to look at how well your blood kind of fat control is, we also look at how high your triglycerides become and how long they take to return to baseline. And this is important because we know that people that have elevated levels of triglycerides after a meal have increased risk of cardiovascular disease.

And the reason is, is because it affects these kind of lipoprotein particles that we've talked about. And in a very simple way, it creates in the long term LDL particles that we know are more atherogenic. So they're more prone to causing atherosclerosis as furring of the artery. And so what our test does is it combines both this postprandial, this post-meal triglyceride measure, as well as looking at the very traditional LDL cholesterol measure.

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It's selling out in the UK and we're working hard to bring it to the US as soon as possible. Sign up to the waitlist at zoe.com slash daily 30. To make sure I've got that, Sarah, you're saying that we sort of measure this response in your blood after you eat this standardized meal and that in the same way that you've been describing that for your body to be healthy, it needs to be able to clean up.

clear away this LDL and not have it hang around, you're sort of measuring the same thing with this big input of fat from your diet. And you're saying, well, if your body can't clear that away, then you start to have all the same sort of negative effects that you're describing with just having high LDL all the time. Whereas if your body is functioning well, your liver is sort of going to clear this away. And you're going to see that actually, even though you did eat, you know,

all of that cheese or whatever it is, it's sort of pulling it back to this low level that your body is meant to be running at. Yeah. I think that it's important to say that it's two slightly different mechanisms. So what's happening with your LDL cholesterol that we've talked about a few minutes ago versus what's happening with the change in triglycerides that happens after you have a meal.

It's two slightly different mechanisms, but it all is in the end increasing our risk of cardiovascular disease and all of it can be modified by diet. And in this case, the benefit of the focus on the triglycerides is that's actually what happens with the food. And so if you're trying to understand what happens as I eat food, like should I be eating a high fat diet or less, you're actually able to sort of measure directly what's going on inside your blood as a result. Yes.

And this is where I think it gets interesting of how changing the type of fat that we eat

depending on your cholesterol levels, depending on this post-meal triglyceride increase can actually have quite a big impact. You know what, that's a brilliant transition. I would love after like a pretty complicated explanation of what's going on because this is obviously quite complex. Let's start to talk about actionable advice. So let's say somebody's listening to this and they're like, that's great. You've explained to me that this is important, that there are these risks. What can people do if they're worried about their high cholesterol?

So this is the good news. You can do a lot. That's brilliant news. And the great news is that there is so much evidence for just how beneficial diet can be in lowering your cholesterol and lowering your LDL, your apolipoprotein B levels. So what I would start with is I would start by thinking about the type of fat we're eating. And so this is where I would caution anyone to change to a low-fat diet because they have high cholesterol. Don't do that.

And I think that's radical for lots of people. I've had this discussion with members of my family who are still being given official advice saying, you have this high cholesterol, you should eat a low-fat diet. So I just want to say this really clearly. If you have high cholesterol, should you switch to a low-fat diet? No.

However, and Jonathan, there's always a however. You need to make sure you're eating the right types of fat. This is really important. So whilst I think that people should follow a moderate fat diet, I don't think people should go to a low fat diet. I think what's really important to say is it has to be from the right types of fat. It has to be from...

poly and monounsaturated fat sources, not from saturated fat sources. And this is where there's overwhelming evidence that adding polyunsaturated fatty acids to your diet, and these are the kind of fats that are found in seed oils, are found in many different plant-based products, many different nuts and seeds, for example, actually have a huge impact on lowering our LDL cholesterol.

So just by increasing your intake of polyunsaturated fatty acids, you can reduce your LDL cholesterol. This is why evidence shows, again, from my own research, if you add nuts to someone's diet, you can significantly reduce cholesterol by 5% to 10% just by adding nuts into the diet. Obviously, it's instead of what we're assuming we're adding nuts in in place of unfavorable fats. We always have to remember that. What are we displacing in order to add them in? And what about animal fats?

Because I feel like what I was always like, well, you know, you've got to eat less red meat. That's correct. Because that is full of fat, but that's fat. So saturated fat we know has a cholesterol raising effect. Saturated fat is one of the most potent factors in our diet that raises cholesterol, increases our cholesterol.

And so what else are the key things maybe just to understand? Also, apart from red meat, is there anything else you definitely should be eating less of? So this is where I want to do a caveat again, is not all saturated fat is equal, actually, in terms of how it impacts

And this is why we need to really be taking a food first approach. And this is something that we do at ZOE and this is something I've spent a lot of time in the work I've done at ZOE in developing our fat scores for foods is thinking not just about the type of fat, but thinking about the food that it's in.

And so we know that as a whole saturated fat is bad for cholesterol, full stop. But we know that we need to worry about some saturated fats more than other saturated fats. So saturated fat from processed red meats, for example, saturated fat from other red meats, saturated fat from some dairy, not all dairy. So for example, butter, we know, yes, it increases our LDL, our bad cholesterol. What we know though is that there are some saturated fats that don't seem to have this negative effect.

And this is because of the cleverness, the amazing food matrix of the structure that these fats are found in. So fermented dairy, such as cheese, such as yogurt, for example, we know does not have a cholesterol raising effect. So I know traditionally, and you've often told me this, Jonathan, that I know, you know, for example, your father was told, no more cheese, you know, you've got high cholesterol. Definitely no cheese. I think that was like, well, you know, it was one of the worst things you could possibly eat.

And 15 years ago, this is what I was teaching the students, that we have to get people reducing their saturated fat intake, reducing red meat, reducing dairy. But actually fermented dairy, which is the cheeses, which is the yogurt, actually doesn't have a cholesterol-raising factor.

effect. I'm not saying that we should gorge on cheese, please let's caveat that. But it's not the primary thing that you're worrying about. And so what my father did was like, as a result of like cutting out all this fat, was eat way more carbs. So we'd like eat lots of white bread and rice and things like this. You know, we talked elsewhere about how that's in general, not great for your health.

Does it have any impact on cholesterol? Yeah, and I get to go back to the physiology lesson to tell you why. So when you eat lots and lots of refined carbohydrates, they're very rapidly absorbed. These are things like white rice, white bread, sugar, etc. The kind of carbohydrates you get in these very heavily processed types of foods that we're eating far too much of now. What happens is they're delivered to the liver.

And then if you're eating them in excess, i.e. your body doesn't need them at that immediate point in time for energy, they're converted then in the liver into triglycerides, which are released, if you remember what I said earlier, in these parcels that contain that apolipoprotein B label on them. Basically, I'm eating my carbohydrate. I'm eating my low-fat diet.

It goes into my liver and my liver says, oh, I've got all the carbohydrate that I need, all the sugar. And it then turns it into fat and pushes it into my blood in exactly the same way as you described to me would have happened if I'd eaten a piece of cheese. Is that...

or the net result is I've got this- Yes, the net result. The net result is I was avoiding, I was trying to avoid getting fat in my blood and all that's happened is my body has basically said, oh, you know, I'm not getting enough fat in my blood so I'm just going to swap this over. Is that- Yes, that's correct. There are going to be an awful lot of listeners feeling like I followed all of this advice from my doctor and the government about like having to eat low fat and hang on a minute, you're telling me that my body just went and sort of did this anyway and had to give up the stuff I wanted to eat. Yes.

Some reason to be a little frustrated by this? I guess if you're following that advice, for sure. And so what happens is then you've got these fats being released from the liver and

that's ultimately come from the carbohydrate, they tend to be slightly high in saturated, in particular monounsaturated fatty acids as well. And we know that saturated fats, the reason as well they're bad for us is because they downregulate this LDL receptor, which is the receptor that I've told you now a few times, Jonathan, if you were paying attention, is the receptor that's on the liver that's responsible for removing cholesterol from our bloodstream. Okay. So having saturated fat,

reduces the activity of the LDL receptor, which is why saturated fat is bad for us because it's preventing the LDL cholesterol being removed. So Sarah, I feel like one of your worst students. Clearly, I can see you saying that you're going to fail the exam. So what you're saying is if you're eating like,

red meat and processed meats and things like this that have these saturated fats, they're actually affecting my liver. So it's suddenly doing a worse job of getting rid of the LDL. Yes. And if you're having excess refined carbohydrates that are churning out saturated fat from the liver. This is like the French fries with my steak.

Yes. Okay. Yeah, love that. Then what's also happening is you're reducing the LDL receptor activity because of that. So you're kind of having a double impact on then preventing the LDL from being removed. Converse to this, if you're having a high polyunsaturated hormone,

fat diet, then you upregulate the LDL receptor. So what happens is you're actually kind of sucking out more of this LDL and you're removing it more quickly. So it's interesting. A lot of this is about sort of making your liver work either better for you or worse for you, depending upon the sorts of

foods that you're eating? Yes. I mean, there's some other kind of things going on as well, but this is kind of, yeah, the main thing. And this is why actually if you increase the amount of fat you're having from these healthy sources, so particularly from polyunsaturated fats, but also some from monounsaturated fats, but it's primarily the polyunsaturated fats that have this very potent effect on

on the LDL receptor, you're going to reduce your LDL cholesterol quite significantly. And this is why all of the evidence shows that people following a high polyunsaturated fat diet reduce their risk of cardiovascular disease by 10, 20, 30%. Do you know someone who's worried about their cholesterol? How about you share this episode with them right now so they can have the best, most up-to-date scientific advice?

And what about foods that say low fat on the label? Because again, this is one of the big things that lots of people even today have been sort of given that advice as a way to try and navigate to like a better diet for their cholesterol. So I'm always cautious of any label that says low, no or reduced because what's been taken out or rather what's been added in

in order to create a food that still functions in the same way when it says low, no or reduced.

Fat actually has a really important role for food, not just because it's important for our bodies, but actually it's what carries the flavor and the texture of food. So I don't know if you've ever tried like low-fat cheese or, you know, low-fat, it just doesn't taste the same. It's the fat that gives it that beautiful kind of mouthfeel and flavor. And so in order to retain some of the pleasure of a food, when you take the fat out, you're going to have to add lots of stuff to it.

And a lot of the stuff that's added to it, firstly, we don't know how it impacts our health. But secondly, what tends to happen is you're creating a food that's very high in these unfavorable types of carbohydrates. So they sort of put in lots of sugar to compensate for taking out the fat, for example. Yeah, I mean, it depends on the type of food. But often, yes, they're often less healthy for us.

I do think, Jonathan, while we talk about carbohydrates, it's really important not to demonize all of them because we know that whole grain carbohydrates, so if we think of whole grain bread, for example, we know that whole grains actually do have a beneficial effect

in terms of our cholesterol. So whilst I'm very pro-increasing the types of healthy fats in our diet, we shouldn't do it at the expense of whole grains. We must do it at the expense of these refined kind of white carbohydrates. So just to make sure that I'm picking up on that right, you're saying it's not like all carbohydrates are bad for your LDL. You're talking about these ones that are high

highly processed that can be, or that just get turned, you know, like a potato or something gets turned into sugar in your blood really fast because then it's like your body's going to end up saying, oh, there's too much of this and I'm going to start creating fats or store it in my fat. Yeah, absolutely. We know that if you increase your whole grain intake, you can reduce your cholesterol levels. We also know if you increase your fiber intake, you can significantly reduce

your cholesterol levels. And fiber is one of these really important components of that portfolio diet that I mentioned, particularly something called soluble fiber. So many people will have heard of something called beta-glucans. I don't know if you've heard of that. Go on, Sarah. Many people who you hang out with will have heard of beta-glucans. I'm going to be the voice of many of our listeners saying beta-what?

Okay, so beta-glucan is a type of soluble fiber. So you've got two different types of fiber. You've got soluble fiber, insoluble fiber. Soluble fiber, such as beta-glucans, is found in oats, but there's other soluble fiber found, for example, in legumes, you know, beans, that sort of thing, pulses, which is why they're so good as well for our cholesterol.

these particular types of fiber can significantly reduce our cholesterol as well. So having a decent amount of those can reduce our cholesterol. And is that back to helping feed the right sort of bacteria in our guts? Or we just don't really know why this is happening? So we know that with soluble fiber, the reason it's beneficial is because actually it changes how we absorb cholesterol. So we know there's a very distinct mechanism for that.

But we know that insoluble fiber, which is the fiber that does reach our gut, that improves our cholesterol via the gut microbiome. And so adding oats, for example, daily to our diet, but I'd have to caution that with a massive, it needs to be the right kind of oats, increases our beta-glucan to the extent that therefore you can reduce your cholesterol. But I would caution against having the kind of oats that are heavily refined against that.

We also know that there's other dietary changes we can make as well as reducing our refined carbohydrates, as well as increasing our fat, healthy fat intake. And the other that's often talked about is adding sterols and stanols to our diet. I haven't seen them in the grocery store last time I checked. So they're actually part of every plant that we eat. Okay.

And they act a little bit in the same way as the soluble fiber. So kind of preventing the absorption of cholesterol. However, you have to have a certain amount of them. You have to have about two grams a day in order for it to be beneficial. It's very difficult to get that on a plant-based diet. You might get near to that, but it's actually quite difficult even if you're on a fully plant-based diet. You can buy products that contain these.

And these are your sterile and stanol kind of shot drinks that you get. So you might have heard of like flora proactive, et cetera. And so to get the required amount, you do need to really be buying these kind of products. They're very expensive. And so for someone that is really concerned about their cholesterol, I might often suggest they try these. But I would say as a starting point, actually increase the amount of polyunsaturated fats in your diet.

I feel like that's a natural transition. You've gone from food to something that's starting to feel like a supplement. It's moving then to medicine. We had many, many questions about statins. And so I'd love to sort of wrap up with that. Many people will either be thinking about taking them, offered them or on them. What are your thoughts? So I need to caveat that as I'm often caveating with that. I'm not a medical doctor and I don't think I'm

comfortable making a decision you know on whether someone should or shouldn't go on statins i think it's something that you need to do in consultation with your clinician i think you need to look at what your current cholesterol level is as well as your overall cardiovascular disease risk is i think the evidence for their effectiveness is overwhelming

that's one thing I'll say from a kind of research perspective, it's undoubtedly they reduce your cholesterol. I do think for people that don't have excessively high cholesterol,

that they could start by looking at their diet, given that we know that diet can have such a big impact on cholesterol. So I would suggest if someone was to ask me what's my personal view, but please, this is not a medical opinion, that look at your diet first. Can you increase your polyunsaturated fat intake? Can you increase your fiber intake? Can you reduce your refined carbohydrate intake?

can you increase the amount of legumes you're having, beans, pulses, etc. And try that for a few weeks and see what happens. The good news is, Jonathan, diet changes cholesterol really quickly. We see a change in cholesterol after about 10 days when people are following a kind of diet that reduces cholesterol. Within two weeks, you see quite a big change. Within a month,

you've seen a huge change. So you can make these changes and then go back to your GP and see a month later, has it significantly reduced your cholesterol? If it's still alarmingly high, that's when I think you need to continue that discussion about statins. With Zoe, the program involves small changes.

you know, that accumulate over time because we know that making small changes are the changes that are going to stick. So if you're making small changes that you progressively add to over time, then I would suggest waiting two to three months till you go back to check.

if you are going all out, and this is what we do in our studies, then you will see it quite quickly. But the reason I'm emphasising how quick it is, is because I think it's a really good motivational factor to say, look, you can quickly change it. And I think a really important point to make as well, Jonathan, is

that it's the duration over the years at which your LDL cholesterol is elevated that's important in terms of cardiovascular disease risk. So I said earlier that if you reduce your LDL cholesterol by one millimole,

over 10 years, you reduce your risk by 25%. If you reduce it over 50 years, you reduce it by 50%. What we want to be doing is making sure there's less time that you have with an elevated LDL cholesterol. That's really helpful, Zara. And of course, I can imagine the team back at Zoe saying, make clear that Zoe is not for the treatment of any disease. Yeah. And I think one last point, I do want to make sure we say during this podcast that

given that we are doing a lot of research in this area of menopause, I would really quickly like to say that you do see a change in cholesterol levels, whether you're peri or postmenopausal. So we see in our own data from our ZOE predict studies that postmenopausal women have a sudden rapid increase in their LDL cholesterol, increases by about 25% compared to if you're... 25% increase? Yes, compared to if you're premenopausal. Now, some of that is a natural effect of ageing.

Okay, as you age, your cholesterol increases irrespective of your diet. But what we know is that men are on a certain trajectory, that their LDL cholesterol is increasing a little bit each year. Women are increasing a little bit each year. What's fascinating, and we've published research on this, as you know, Jonathan, is as soon as you hit the menopause, suddenly your trajectory changes. You actually overtake men as women in your LDL cholesterol levels.

And this is because we know that estrogen, which is what you lose during the menopause, is a really strong activator of that LDL receptor. So we know why this happens. And so this is when diet becomes even more important. But the good news is, again, is that you can somewhat try and reduce that increase that you have in cholesterol postmenopausally by following a healthy diet, according to what we've just suggested.

Amazing. Sarah, thank you so much. I have so many more questions, but we're definitely at time. I'm going to try and do a little playback and correct me if I got this wrong. My takeaway from discussing the complexities of what's going on is, in a sense, it's quite simple that today you're saying the latest science says really focus on this LDL number. You don't want that to be high. If it is high, it's a problem. It's going to lead to big increase in risks around heart disease.

You were saying HDL, you don't feel quite as strongly about it as people have probably done even five or 10 years ago. So focus on that LDL. There is this APOB measure. So some people have seen that from their doctors, and I think that's increasingly happening in the States. That's an even better measure, but they're sort of saying the same sort of thing.

Don't worry about the cholesterol in your diet. That's got nothing to do with this. Actually, your cholesterol is very much driven by processes that are going on inside your body. So it's a marker that something that's bad going on. And interestingly, your liver is playing this important role, which I'm not going to try and play back because I don't think I've understood it.

well enough to be able to do that. There's both like, you know, clearing it away, but also making these fats, these triglycerides. And so a lot is like, is your body working in the right way that there's this sort of parallel, um, mechanism that's going on when we eat food and eating fat is really important. The right sort of fats can really lower, um, our cholesterol. The wrong ones can make it worse. One of the reasons why we do this test for everybody, um,

who becomes a Zoe member is to understand how your body is working actually with eating food, eating these fats, because that's so important for understanding how to give you the right advice. That there's a 25% increase in LDL as a consequence of going through menopause, which is an enormous shift. And you're saying before this, suddenly women have much lower levels than men and like afterwards they end up above. So you can see why there's such a profound change in your body.

And also I think why, you know, I'm thinking now about sort of friends and family, it's sort of striking how often they seem to have this diagnosis around this time period, which I guess is not by chance then, Sarah. And then you said like, what can you do? And the good news here, I think, is beyond statins, which you said can be very effective, there actually is an enormous amount that you can do through diet and lifestyle, which I think is always really exciting to hear that you're not just stuck with it.

And that the advice is basically exactly the opposite of the advice that my dad was given 40 years ago. So rather than saying, don't eat any fat, you're actually saying that if you're eating the right healthy fats, you can actually reduce your cholesterol. And so what that does mean is, yes, my dad was told to eat less red meat. So that's true. But he should have been eating more healthy fats as a result.

Instead, he moved to eating more bread and potatoes and things like this. And Sarah is rolling her eyes because she's like, "Well, that's terrible advice," because your body has this ability to take these carbohydrates on. And if you're eating too much of them, that liver you talked about again is turning it into fats, and then you can end up actually having this high LDL as a result.

Don't feel you have to move to a low-fat diet. Do feel that you really need to change what you're eating. Also, do really think about your carbohydrates, though. So actually eating these sort of poor-quality, highly refined food or ultra-processed food could be really bad for your fat. However, eating things that were high in fiber and whole grains could be really good. And I think the final thing that you said is if it says low-fat food on the label, it's almost certainly something to avoid.

Yes. I'm always cautious saying almost certainly, but yes.

I think that's fair to say. I believe we did a podcast on ultra processed food. And I just remember this thing about like almost any food that has like a printed health claim on it, you know, like low fat or added protein or any of these things you should be very cautious about. So that has stuck in my head. I think almost is the right word. I mean, you can take Greek yogurt and you can have some very good low fat Greek yogurt that hasn't been, you know, fiddled with all of these other ingredients.

Sarah, thank you so much for walking us so clearly through a very complex topic. I feel I understand it much better than I did at the beginning of the podcast, and I'm sure lots of listeners will as well. Thank you. Great. Pleasure. Thank you. I loved having Sarah on the podcast today, and I hope you learned something new from her. Now, if you listen to this show regularly, you already believe that changing how you eat can transform your health, but you can only do so much with general advice from a weekly podcast.

If you want to feel much better now and hopefully live many more healthy years, you need something more. And that's why more than 100,000 members trust Zoe each day to help them make the smartest food choices. Combining our world-leading science with your Zoe test results, Zoe is your daily companion to better health for life. So how does it work? Zoe membership starts with at-home testing to understand your unique body.

Then Zoe's app is your health coach, using weekly check-ins and daily guidance to help you shift your food choices to steadily improve your health. I rely on Zoe's advice every day, and truly it has transformed how I feel. Will you give Zoe a try? The first step is easy. Just take our free quiz to find out what Zoe membership could do for you. Just go to zoe.com slash podcast, where as a podcast listener, you'll also get 10% off.

As always, I'm your host, Jonathan Wolf. Zoe Science and Nutrition is produced by Julie Pinero, Sam Durham, and Richard Willem. The Zoe Science and Nutrition podcast is not medical advice. And if you have any medical concerns, please consult your doctor. See you next time.