Updated 23rd January 2023

Foods to lower your cholesterol

More than half of us have high cholesterol — and new research suggests that having even slightly raised levels in our 30s could significantly increase our chances of developing heart disease.

Medication is a common fix, but it comes with side effects. So, today we’re looking at how much changing our diets can help.

In this short (ish) episode of ZOE Science & Nutrition, Jonathan and Sarah ask: Can we lower our cholesterol by changing our diets?

Studies referenced in the episode:

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This transcript was produced by Fascinate Productions.

Transcript

[00:00:00] Jonathan Wolf: Hello and welcome to ZOE Shorts, the bite-sized podcast where we discuss one topic around science and nutrition. I'm Jonathan Wolf, and today I'm joined by Dr. Sarah Berry, and today's subject is foods to lower cholesterol. 

[00:00:21] Sarah Berry: So Jonathan, around half the adult population in the U.K. and the U.S. have high cholesterol and many people are completely unaware that they have high cholesterol. Medication to reduce cholesterol is projected to be worth almost 20 billion dollars by 2027. Now, we all know that statins are one of the most prescribed drugs globally, but there may be other ways that we can reduce our blood cholesterol levels, specifically the food that we eat. 

[00:00:48] Jonathan Wolf: So Sarah, with your years of experience in the field, I'm sure you have some terrific insight into how dietary changes can reduce cholesterol.  

[00:00:57] Sarah Berry: Yeah. There's some fabulous research out there showing just how much diet can impact our blood cholesterol levels.  

[00:01:04] Jonathan Wolf: Then let's get into it. Let's start with some shocking numbers, Sarah. 

The World Heart Foundation states that high cholesterol causes 4.4 million deaths every year. That's around 7% of all deaths, so high cholesterol is a global health issue.  

[00:01:20] Sarah Berry: Yeah, that's right. Jonathan. Beyond Deaths, the latest data from America's Center for Disease Control and Prevention states that nearly 94 million American adults could be considered to have high blood cholesterol levels. 

[00:01:34] Jonathan Wolf: And I know we've discussed cholesterol before on this show, but if you're like me, you find it all a bit complicated and about 10 minutes after Sarah explains it, you forget the whole thing. So, Sarah, could you just start again and remind us what is? 

[00:01:49] Sarah Berry: So cholesterol is made in our liver and our bodies need it to produce things like vitamin D, bile acids, hormones, and also create all the new cells in our body. 

[00:02:01] Jonathan Wolf: and I know we discussed on a previous podcast that you can go and listen to if you're interested, that there is also cholesterol in some of the foods we eat. And we call that dietary cholesterol cause it's cholesterol we get from our diet. Now, Sarah, I might not have remembered all the details of how cholesterol work, but I do remember that you explained on that podcast that the latest science shows that dietary cholesterol is not very important for affecting the cholesterol in our blood for most people. 

[00:02:27] Sarah Berry: Yeah, that's right. Well remembered. Jonathan.  

[00:02:30] Jonathan Wolf: Thank you, Sarah. Now on that podcast, you also explained that some cholesterol is good while other cholesterol is considered to be bad. Can you explain this again?  

[00:02:42] Sarah Berry: So low-density lipoprotein that we also call L D L. Cholesterol is your bad cholesterol, and simply put this transports cholesterol from your liver around your body. 

You also have another type of cholesterol called high-density lipoprotein, also called HDL cholesterol, which is your good cholesterol. In really simple terms, what this does is return cholesterol to the liver to be removed from circulation. And our bodies have a complex process that maintains the balance of these good and these bad cholesterol in our blood for most people. 

Now we do know that the ratio of good to bad cholesterol, and particularly the amount of bad cholesterol to this LDL cholesterol is really important in terms of our general health. And if we have high levels of this bad LDL cholesterol that can contribute to things like the hardening of our arteries and ultimately lead to heart disease. 

[00:03:36] Jonathan Wolf: Okay, I think I've got it this time, Sarah. So when we talk about reducing cholesterol, what we mean is reducing this bad cholesterol, this LDL, while increasing the good cholesterol, which is the HDL in our blood. Have I got that right at last?  

[00:03:51] Sarah Berry: Yeah. Well done. , top marks, Jonathan.  

[00:03:54] Jonathan Wolf: Alright. Thank you. I think it's important to emphasize to people, not just to look, therefore, at the total cholesterol, because a change in your diet might not show a huge change in your total cholesterol, but you might see that you're reducing some of your bad cholesterol while slightly increasing your good cholesterol. 

So, can our diet change our cholesterol levels, or are drugs the only things that can have a big impact?  

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[00:04:21] Sarah Berry: So the best way to illustrate just how effective food and our diet can be at lowering cholesterol comes from the portfolio studies, and these are key nutrition science experiments showing the power of food in relation to our health. the concept of the portfolio diet isn't very straightforward. What you do is replace certain foods in your diet with other foods and ingredients that have been shown to lower cholesterol, and it's centered around four key elements. It's centered around soy protein, plant sterols, tree nuts, and soluble fiber.  

[00:04:53] Jonathan Wolf: And did it work?  

[00:04:54] Sarah Berry: Absolutely. So it was shown to reduce cholesterol by 30%. 

Now, this is similar to the level of reduction that we see in cholesterol-lowering from medication like a statin.  

[00:05:05] Jonathan Wolf: So 30%, that sounds pretty incredible. So does ZOE recommend this diet to people with high cholesterol?  

[00:05:12] Sarah Berry: It is an incredible dietary pattern to follow, but there's a catch with a portfolio diet that it's really difficult to follow. 

So it's therefore more of a science experiment showing us what is the potential of food in terms of lowering cholesterol rather than something really practical I think in the long term. I think there's a more realistic dietary pattern that's also been shown to be effective in reducing cholesterol, and this is the Mediterranean diet. 

[00:05:40] Jonathan Wolf: I love the concept of the Mediterranean diet, which I think was invented by a bunch of nutritional scientists living a long way away from the Mediterranean because I've spoken to a lot of nutritional scientists now, and every single one has a slightly different definition, of what's in it, which is probably not surprising when you think that people living in Italy, Greece, Morocco, and Israel all think they're eating a Mediterranean diet. If you go on holiday to these places, they're eating a very different diet.  

However, I think everyone agrees, Sarah, that it's about eating plenty of fruit and vegetables, whole grains, nuts, and olive oils. And then I think people start to argue a lot more about, fish and lean meat and dairy products and the exact proportions. 

[00:06:24] Sarah Berry: While it's not quite as drastic as the portfolio diet in reducing your cholesterol, it's a sustainable diet that lets you enjoy food that would be cut out if you followed a more restrictive diet like the portfolio.  

[00:06:38] Jonathan Wolf: And so Sarah, to be clear for people who are listening to this, while eating foods like eggs that are high in cholesterol won't necessarily raise your cholesterol, some foods can make your cholesterol go down. And if so, can you explain sort of what those foods are?  

[00:06:53] Sarah Berry: Yeah, so we know that dietary cholesterol, so cholesterol that's in the food that we consume has only a really small impact on our blood cholesterol levels. But what we do know is that saturated fat-rich foods and particular types of saturated fat can have quite a potent effect on raising our blood cholesterol. 

These are the kind of fat that is found in red meats, lots of ultra-processed foods such as pastries, and also in some dairies such as butter.  

[00:07:25] Jonathan Wolf: And what about carbohydrates? Because lots of people will be listening to this and saying, "I've got high cholesterol, so I'm not gonna eat any fat, and therefore my cholesterol is going to go down." which sounds logical. Is it correct?  

[00:07:38] Sarah Berry: No. So this is a big mistake I think that lots of people make, and unfortunately, there's lots of really poor misinformation out there about people with high cholesterol being told to follow a low-fat diet. What we do know is that if you consume healthy Fats and healthy oils, you can improve your circulating blood cholesterol levels. 

So rather than worrying about the amount of fat that you are consuming, you should be thinking about the types of fat. So the types of fat that we know, increase cholesterol, as I've just said, are saturated fats. But we know that the poly and monounsaturated fats that are found in many vegetable oils, nuts, and seeds can reduce our blood cholesterol levels. 

Now the problem is if you take out the fat from foods so that you choose low-fat versions of foods, It's gotta be replaced with something because fat is the component in food that gives the lovely creamy mouth feel. It carries much of the flavor. So if you strip out the fat, you've got to replace it with something that still confers that nice mouthfeel and that great flavor to the food. 

Quite often refined carbohydrates or sweeteners or other kinds of ingredients are added back into the food. We know that these are bad for us because we know that they impact your liver, which is involved in the production of cholesterol. But also they increase another type of fat that circulates in your blood, which is called triglycerides. 

And we know that this is unfavorable in terms of cardiovascular disease if it's elevated. 

[00:09:13] Jonathan Wolf: Amazing. So I think now that we understand a bit more than what we eat can cause high cholesterol and it could be a carbohydrate or a fat, can you be a bit more specific about what a listener should do to change their diet if right now their doctor has told them that they have high cholesterol or they know that it's in their family, and are there any smart swaps that they could do without completely changing the way that they eat. 

[00:09:37] Sarah Berry: Absolutely, and I think it's making simple smart swaps, as you call them, Jonathan, that is personalized to your body, but also your preferences. They're the ones that people will most likely stick to and therefore lead to sustained improvements in blood cholesterol and your blood cholesterol can change quickly from dietary changes. 

So we see changes in our studies as little as 10 days to 14 days in blood cholesterol. That should motivate people that quick changes, but sustainable changes will have an impact.  

The kind of things that you could do is to try and eat less red meat and less processed foods because these have the types of fat that we know increase your bad cholesterol. You could introduce many fiber-rich foods such as beans and vegetables, and also plant-based protein sources that we know will lower your cholesterol. Spreads are also a good substitute for butter since most spreads are made from vegetable oil. So they contain these healthy, unsaturated good fats that I've talked about, the poly and monounsaturated fats. Although Jonathan, this is quite a controversial area.  

[00:10:46] Jonathan Wolf: I remember from our previous episode that many of the foods that are high in cholesterol are also high in saturated fat. And this may have led to some of the previous misinformation suggesting that it's the cholesterol in some food such as red meat that explains why red meat, for example, is bad for us. 

[00:11:04] Sarah Berry: Yeah. And with regards to cholesterol, Jonathan, saturated fats are what's increasing the bad cholesterol in our blood, not dietary cholesterol.  

[00:11:13] Jonathan Wolf: Yes. And there could have been this confusion, right when they looked at it because some of those foods happen to have high cholesterol as well. So we now understand the mechanisms today and therefore the high cholesterol in the egg or the meat is no longer being blamed for it. But the red meat is still in the dock, still in trouble. We just understand that it's sort of different properties of red meat that are causing us problems. 

[00:11:37] Sarah Berry: Absolutely. So if we think of the liver, for example, the liver is high in cholesterol, but also high in saturated fat. If we eat lots of liver, we'll have an increase in bad cholesterol, but it's not the cholesterol in the liver that's going to cause this. It's the saturated fat that will cause this. 

[00:11:56] Jonathan Wolf: Well look, Sarah, I think it's a brilliant way to come around and we've had a slightly longer podcast than usual. Because I think it's such an important topic and it is complicated if you're gonna sum this up for somebody listening and saying, 'okay, so I am worried about my cholesterol.' what should they do? 

[00:12:10] Sarah Berry: So I think that there's really clear evidence to show that our diet can significantly alter our cholesterol. There's clear evidence to show that. It's the type of fat that's important and not the amount of fat that's important to consider. So please don't follow a low-fat diet, but please change to healthy oils and also be motivated in knowing that a dietary change can induce a change in your cholesterol, and it's little as two weeks. 

[00:12:39] Jonathan Wolf: I'd like to pick up on, the first part of what you're talking about, which is the misinformation. It's something I've talked about before, that when I was growing up, my dad was told that he had, very high cholesterol, he was, living in the States at the time, and he was told to eat a very low-fat, and therefore a very high carb diet. And I think today, we know, every nutritional scientist I talk to says, 'oh yeah, we know that isn't the right advice and yet I still hear stories from friends and family that, they get a note from, you know, their physician or the NHS here in the U.K. saying you've got high cholesterol and therefore here's this guidance on what you should eat. 

And is basically saying you should be eating all of this low-fat food. You should be avoiding all of these high fats like olive oil and nuts and things like that. What's your take on this, Sarah?  

[00:13:28] Sarah Berry: My thoughts are that's the wrong advice to be giving to people We now clearly known the amount of fat in our diet is not what the problem is. 

It's the type of fat that's the problem. And pushing people to high carbohydrate diets we know is not good for our heart health. So, for anyone that has high cholesterol, I would encourage you not to cut down on the amount of fat you are consuming. But I would encourage you to think about the type of. 

And so this takes us back to what we mentioned earlier, so increasing the amounts of these healthy oils, so the mono and polyunsaturated oil. So these are vegetable oils, extra virgin olive, and reducing the saturated types of fat that you find in ultra-processed foods and red meats.  

[00:14:16] Jonathan Wolf: Thank you, Sarah. And just before I wrap up, I'd love to talk about individually personalized responses. I think one of the things we do in this podcast is we try hard to make sure that all the advice is available for everybody and don't say, 'Hey, you have to go and do these tests' but I think in this particular case, it feels wrong not to talk about the differences that we see because I think they're just so striking. We've had more than 50,000 people do these tests, which I think Sarah, you can describe in a minute, which is the same as the tests we originally did on thousands of people in these labs where we look at your responses to the sort of standardized meal. 

We see this amazing variation in response to high-fat meals, which seems to have some very big implications for what's right for me as an individual. Could you maybe touch on that a little bit and explain what's going on there?  

[00:15:03] Sarah Berry: Yeah. So one of the things that we test at ZOE is people's blood fat responses to a high-fat meal. 

So we give people these muffins that contain 50 grams of fat, and we look at how quickly and for how long circulating levels of blood fat change. We measure this from a measure called triglycerides. The fat in the meal that we consume increases the levels of blood triglyceride levels.  

People respond hugely different in terms of how much their triglycerides go up and how long they stay elevated. This is even despite them having the same meal as other people, and we see about a tenfold difference in how one person responds. Versus another person's response, and we know this is down to loads of different factors. 

It's partly down to our genetics. We know it's partly down to our gut microbiome, which is the trillions of bacteria that are living in our gut. We also know it's partly down to our age or our sex, or even how much we weigh. There are loads of different factors that shape how we respond to high-fat foods and how our circulating levels of fat change following our consuming these high-fat meals. 

[00:16:22] Jonathan Wolf: And I think what's interesting is it's not just if you have high cholesterol, therefore you're in the third of people who have this bad response, or if you have low cholesterol, you're definitely in the good response, it's very different. So basically without doing this test, you don't know what's going to happen. 

Obviously, are people who have very high fasting fat levels, so you have some idea of certain people. But in general, this response to food is a different measure, isn't it, than just the sort of high cholesterol levels that you would get tested by your doctor. 

[00:16:55] Sarah Berry: Yeah. So when you go to a doctor and they test your cholesterol levels, they do what's called a full lipid test. That isn't just your cholesterol, so it isn't just your HDL and LDL cholesterol. They also always test something called your triglycerides, and we know that triglycerides are equally, as important as cholesterol in our health. This is something that's been understudied and it's really interesting because we know that diet can play a huge role in changing our triglyceride levels. And this is what we've been testing a lot with the work that we've been doing at ZOE.  

[00:17:32] Jonathan Wolf: Amazing. And I think for me, this is one of the big takeaways in the same way we talk a lot about blood sugar. Which is, as you understand your own sort of fat control, it has a lot of influence on what you do. 

It doesn't mean you need to give up fats. You know, extra virgin olive oil is generally good for everybody, but certainly thinking about the amount that you want to take and certainly thinking about what's going to happen if you're starting to eat these less healthy fats, you see this very big change. 

And so you could have somebody. Who has high cholesterol, but actually whose fat control is pretty good? They're told to move to this low-fat diet and they swap, they've been able to deal with this fat. Well, it turns out their blood sugar control is bad and they're switching to something much, much worse Right? That their liver is then struggling with and it's terrible advice. And so I think it is one of the most striking things that's come out of ZOE for me over the last five years.  

[00:18:20] Sarah Berry: yeah, If there's one thing that I could say to people is do not go on a low-fat diet.  

[00:18:27] Jonathan Wolf: amazing, and we've been lucky to have one of the world's foremost experts on fats and nutritional science today, Sarah. If out of today, learning more about cholesterol means you'd like to understand more about the right diet for you based upon how your body responds to food. You might want to try ZOE's personalized nutrition program to improve your health, and if so, you can get 10% off by going to joinzoe.com/podcast

I'm Jonathan Wolf.  

[00:18:52] Sarah Berry: And I'm Sarah Berry.

[00:18:53] Jonathan Wolf: Join us next week for another ZOE podcast.

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