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  • Hello, and welcome to Zoe shorts, the bite-size podcast, where we discuss one topic around

  • science and nutrition.

  • I'm Jonathan Wolf.

  • And as always, I'm joined by Dr Sarah Barry and today's subject is high cholesterol foods.

  • Cholesterol in our food has a really bad reputation.

  • I think.

  • And many people think of it as a bad thing, but like many of the foods and nutrients we

  • discuss here, it's not quite as simple as that.

  • And cholesterol can be found in every cell of our body and we need it to be able to function

  • normally.

  • And in this episode, we want to find out which foods are high in cholesterol and whether

  • it matters if we eat them or not.

  • You'll also notice that this is a word I find hard to say.

  • So spot how many times I say it wrong.

  • Fortunately, I find it quite easy to say the word cholesterol.

  • Cause it's something I've researched for about 20 years.

  • I think there's quite a clear answer to this one as well.

  • Jonathan.

  • Excellent.

  • So let's get into it.

  • So let's start with what is cholesterol.

  • So you said cholesterol is essential to the normal function of our bodies.

  • Many of our listeners will consider it to have a bad reputation.

  • Some of our listeners may even be on medication like statins to reduce their cholesterol.

  • So before we delve any deeper, what is it, Sarah?

  • Yeah.

  • So, Jonathan, cholesterol's a waxy substance and it's made in our liver.

  • Our bodies need it to make ourselves and to produce vitamin D for example, bile acids

  • and hormones, as well as making cholesterol in our liver.

  • We can also get cholesterol from our diet.

  • Our bodies have a complex, but a very good process that maintains the balance of cholesterol

  • in our blood.

  • So this is another one of those things, you know, like carbs or something where people

  • like, oh, this is bad.

  • And then it turns out that we all have it and it plays an essential role inside our

  • bodies.

  • And reality, you know, is more complicated than the first picture.

  • Is that right Sarah?

  • Yeah.

  • And when we refer to cholesterol as being good or bad, we are referring to the cholesterol

  • that's circulating in our blood.

  • So we're not referring in this scenario to the cholesterol that we get from our food,

  • which we call dietary cholesterol.

  • Now, most of the cholesterol in our blood is produced by our liver.

  • And it's this cholesterol that's released from the liver to move around the body in

  • your blood in little packets, which we call lipoproteins.

  • Many people think of these lipoproteins as cholesterol.

  • There are two main types of lipoproteins.

  • One is LDL.

  • And this is what we refer to as our bad cholesterol, and very simply put it transports cholesterol

  • from your liver around your body.

  • The other type is HDL, and this we call your good cholesterol.

  • And again, in really simple terms, what this does is return cholesterol from your body

  • to your liver in order for it to be broken down again.

  • Got it.

  • So high levels of HDL cholesterol keeps our risk of heart disease low.

  • As we know our body is removing cholesterol, but if we have high levels of LDL, that's

  • the bad cholesterol, then this can contribute to things like hardening of the arteries,

  • heart disease, and lots of other diseases, which I know you've been studying for many

  • years, Sarah, in terms of the link from food through to how this happens.

  • Yeah, that's right.

  • It's quite a simplistic way of saying what's happening, but you're correct overall in that

  • summary.

  • Now for many years, though, the consensus was that if we wanted to lower our blood cholesterol

  • levels, we should make considerable efforts to reduce the amount of cholesterol that we

  • were consuming so that we should try and reduce our dietary cholesterol to reduce our blood

  • cholesterol level.

  • So Sarah, you said that our bodies make all the cholesterol we need, but what about foods

  • that are high in cholesterol?

  • My dad was diagnosed with high cholesterol in his thirties, and this was, you know, 40

  • years ago.

  • And the doctors in America at that time advised him to move to a very low-fat diet and a diet

  • that was very low in cholesterol.

  • Which meant that he had to move out of all of those foods.

  • And as a result ended up eating lots of, um, carbohydrates, highly processed carbohydrates.

  • Yeah.

  • And that's part, of the problem with the advice that was given that there was a move for people

  • to consume these low cholesterol, low fat, and highly processed diets.

  • Now we know that the cholesterol that we eat has a very small role on the cholesterol that

  • circulates in our blood.

  • Now, typically the foods that we know are high in cholesterol, mostly come from animal

  • sources.

  • So do contain a high amount of saturated fat.

  • And these include red meats, pork, chicken, shellfish, butter and cheese, but there are

  • also eggs as well.

  • And so what about eggs?

  • I know they are the poster child of a food that's associated with high cholesterol and

  • there was definitely, always a naughty treat at home when I was growing up.

  • So for a long time, Jonathan, eggs have been thought to be bad for your heart because of

  • their cholesterol content.

  • The large egg contains around 200 milligrams of cholesterol.

  • And 200 milligrams sounds like a lot.

  • So I guess that explains why my dad felt that eating an egg was naughtier than ice cream.

  • However, I think looking at the latest science it's clear that we don't believe in this advice

  • anymore.

  • Yeah.

  • So I think that in the last decade, research has shown that at normal intakes are around

  • three, 300 milligrams.

  • A day, which is, the typical intake, in most of the US or the UK, dietary cholesterol has

  • very, very little influence on a person's blood cholesterol level.

  • And I think this is another great example of how much the latest nutritional advice

  • has changed from what we were told in the past.

  • And I think that leads into what you said in an earlier episode, Sarah, that no food

  • is entirely good or bad.

  • So we know that eggs are an excellent source of protein.

  • They've got lots of healthy fat and also got lots of vitamins and minerals.

  • So there's sort of, you know, I think.

  • Tim has said, this is probably a bit like a nut, right?

  • That's going to ultimately feed in this case a little chick instead of growing a tree.

  • If that means that for people like me with very poor blood sugar control, but quite good

  • blood fat control eggs can actually, I think be a great part of the diet.

  • And if eggs have been redeemed, does that mean that we no longer need to worry about

  • any of the other foods that are high-end cholesterol, and you talked about, you know, these red

  • meats and things like this?

  • For many years, the dietary guidelines for Americans have recommended keeping cholesterol

  • intake from our food.

  • So the dietary cholesterol is low.

  • So to know more than about 300 milligrams per day, and that's equivalent based on what

  • I've just told you about one and a half eggs per day, but large studies and many studies

  • that have gone on to look at this, actually do not find a conclusive link between the

  • amount of cholesterol that we are eating in our diet and circulating bad cholesterol.

  • So the LDL and also the risk of heart disease.

  • We also know is when you eat foods with cholesterol, the levels in your blood do go up.

  • But as a result, your body changes the amount it produces.

  • Overall, we know that increasing dietary cholesterol alone is not associated with increased heart

  • disease risk.

  • And actually, as a reflection of this in 2015, the dietary guidelines for Americans removed

  • the 300 milligrams per day recommendation.

  • And we all know it takes a long time to change guidelines, but the fact they've made that

  • shift shows you pretty conclusively, right?

  • That the science has concluded that this whole guidance about focusing on cholesterol in

  • food is not something that's believed in.

  • So all of this information might come as a surprise to some of the audience.

  • And many of you like me might feel better about enjoying eggs regularly in your diet.

  • , but what if we have been diagnosed with high cholesterol, what can we do about it?

  • Again, we looked at the latest advice.

  • It turns out that there may be some significant ways in which we can reduce cholesterol in

  • our blood that don't require medication or a change in diet.

  • So there's some research that's been published recently showing that quitting smoking.

  • Can improve HDL cholesterol levels and apparently within a year of quitting your risk of heart

  • disease is half that of a smoker.

  • Apparently, we also know that increasing your physical activity, losing weight and dietary

  • changes can reduce the level of that bad HDL cholesterol in your blood.

  • What about specifically thinking about dietary changes, Sarah?

  • Yeah.

  • So I think the best evidence to illustrate just how effective food and a whole dietary

  • pattern change can be at lower cholesterols comes from the portfolio studies.

  • This constitutes a dietary pattern that focuses on four key elements.

  • These are soy protein, plant sterols, tree nuts and soluble fibre.

  • This portfolio-style dietary approach has been shown to reduce cholesterol by up to

  • 30%.

  • And this is similar to the kind of reduction that we see in cholesterol from people taking

  • statins, which are drugs often given to lower cholesterol.

  • That's amazing.

  • And Jonathan, this is because the specific components of each of these four parts of

  • the portfolio separately have quite a reasonable effect on circulating blood cholesterol.

  • Now, one thing to say is that the portfolio diet isn't very easy to follow a diet.

  • It's a fantastic proof of principle that I use when I'm teaching students about how diet

  • can modify cholesterol, but it is quite hard for the majority of people to follow.

  • So a more realistic diet that can be followed and that we know is effective in lowering

  • cholesterol is a Mediterranean diet.

  • And we know that there's a very broad range of what a Mediterranean diet is, but all of

  • these tend to be much gut healthier than the sort of typical diet that we have.

  • To come to conclusion out of all of this, it seems that in the past dietary cholesterol

  • was considered to be a bad thing, but from what we've discussed today, am I right in

  • thinking that our opinions have changed significantly?

  • Yeah.

  • So there has been a change in opinion, a