Updated 17th August 2023

Butter vs. margarine: What does science say?

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    Whether you’re frying, baking, or topping your toast, most of you will eat either butter or margarine at some point today.

    The fact that these spreads are such a staple means that we need to know their effects on our health. And it might surprise you to learn that this impact has changed quite dramatically over the past 20 years.

    In today’s short episode of ZOE Science & Nutrition, Jonathan and Dr. Sarah Berry ask: Which is healthier, butter or margarine?

    Follow ZOE on Instagram.

    Episode transcripts are available here.

    Is there a nutrition topic you’d like us to explore? Email us at podcast@joinzoe.com, and we’ll do our best to cover it.

    ZOE Science & Nutrition

    Join us on a journey of scientific discovery.


    [00:00:00] Jonathan: 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 butter versus margarine.

    [00:00:16] Sarah: Jonathan, this is a debate that's echoed across many households. Are you team butter or are you team margarine? Now, they might appear quite similar, but they affect our bodies in different ways.

    [00:00:28] Jonathan: And do you think we'll be able to crown a champion by the end of this episode?

    [00:00:31] Sarah: Well, what we will be able to do is clear up some misconceptions that we're gonna address and there's some excellent research that will definitely help us get closer to an answer.

    [00:00:41] Jonathan: Great stuff. Let's spread the word! So to start our journey into spreads, I want to take you back to 19th century France. The year is 1869 and France is at war. In an attempt to feed his troops for less money, Napoleon calls for the development of a low cost alternative to butter. Step forward a man with a wonderful name, Hippolite Mège-Mouriès, who used animal fat and milk to create the first ever margarine.

    [00:01:13] Sarah: So not suitable for vegetarians then?

    [00:01:17] Jonathan: I think not.

    [00:01:20] Sarah: But Jonathan, that changed in 1902 when a German scientist developed a process to harden oils using a method called hydrogenation.

    [00:01:27] Jonathan: Okay, that sounds pretty scary. What exactly is hydrogenation?

    [00:01:31] Sarah: Okay, so Jonathan, you're gonna have to humor me here and allow me to get a little bit technical just for a second. So hydrogenation is a process that turns a liquid oil like canola oil or soybean oil into a hard fat like margarine. It's a chemical process that changes the unsaturated fatty acids in the seed oil to a saturated fatty acid. And what this does is changes the chemical structure of the oil, but increases the melting point or more plainly makes it a harder fat.

    [00:02:03] Jonathan: Okay, so I think I understand what you're saying is the oil is now a solid. The unsaturated fat that was in the oil has now become a saturated fat?

    [00:02:13] Sarah: Well, it depends on exactly how it's made. So the techniques have moved on quite a bit and how margarine is made today is quite different to how it was made back then. It also depends on where you live, and we can talk a little bit about this in a minute, but broadly speaking, unsaturated fatty acids usually make up about 65 to 80% of the fats in margarine.

    [00:02:36] Jonathan: So that sounds sort of really amazing. What you're saying is that we can turn oil into margarine with these modern chemical techniques. So how is that different from the process of turning milk into butter?

    [00:02:47] Sarah: So, to make butter milk is solidified by churning. So if you try and imagine an old fashioned butter churn, you're probably picturing someone moving a long wooden plunger up and down in a barrel full of milk.

    [00:03:00] Jonathan: Which I'm guessing is not how fat in the butter turns up in the shop, but it's definitely sort of my mental image that makes me feel good about it.

    [00:03:08] Sarah: Do you know what, broadly speaking, the same principles apply. By churning this milk, the milk is being agitated and the fat molecules clump together, and after a lot of this hard churning, you are left with a solid lump of butter and then a very low fat liquid at the bottom called buttermilk.

    [00:03:27] Jonathan: The fats in the butter that you're referring to here, those are saturated fats, is that right?

    [00:03:33] Sarah: Yeah, so butter is what we would call a saturated rich fat, so about 60 to 70% of the fatty acids in butter are saturated. Unlike the margarines, which have about 70% unsaturated fatty acids.

    [00:03:48] Jonathan: So our, our team did some research to look at actually the consumption of butter margarine in the states over the, almost the last a hundred years. So at the start of the 1940s, apparently consumption of butter really started to drop, and in the 1950s, low price margarine took over as the most popular spread and interestingly since then, butter consumption has actually remained pretty stable at around four to six pounds which is two to three kilograms per person per year. However, interestingly in the 1990s, margarine consumption started to dip quite sharply. And since 2013, uh, in the states, butter has once again been the most popular option.

    [00:04:32] Sarah: Yeah, they're really interesting statistics, Jonathan. And this dip in margarine consumption that you've talked about was largely to do with people being concerned about the types of fats that were in margarine.

    [00:04:42] Jonathan: That's really interesting. So Sarah, I'd love for you to take a look at the fats then and the health impacts of both butter and margarine. From what you've told us so far, one of the main differences between the two is the proportion of saturated versus unsaturated fats.

    [00:04:58] Sarah: Yeah. So one of the biggest differences is that butter has more saturated fat and margarine has more unsaturated mono and polyunsaturated fats, and this is largely why butter has been perceived to be potentially unhealthy because of the large amount of saturated fat that's in butter, because we know that saturated fat raises your levels of bad cholesterol, LDL Cholesterol. We know that saturated fat can increase inflammation, we know that it can also affect other processes in our bodies, such as clotting, for example. Now, if you want to find out more about this, we do have various podcasts where we've really dived into the effects of both saturated fats and also fats and oils on our health. So we do have the podcast, ‘Fats and Oils. What's the real story?’ And also one just on saturated fats, whether they're monstrous or misunderstood. So I would recommend people go and have a deep dive into those to really understand this a bit more.

    [00:05:56] Jonathan: So based upon what you're just saying, it sounds like butter is sort of in the naughty corner because obviously that's the one with all the saturated fats. It hasn't been rescued by, you know, magic bacteria at this point. But I think a lot of people listening to this will say, well, hang on a minute, what about the processing that's associated with making margarine? Right? We've talked about processed foods and particularly ultra processed foods many times on this show, and it looks like margarine belongs in that camp. So does that in fact mean that margarine is less healthy than butter?

    [00:06:30] Sarah: So to understand this, Jonathan, we need to first look at how the manufacturing of margarine has changed over the last few decades. 'cause this is where I think there's a lot of misconceptions that we first need to clear up before we look at how margarine is made today. This is most notably regarding the presence of trans fats in how they were historically made.

    [00:06:51] Jonathan: ah, yes. Trans fats. Again, we had a podcast with you explaining this, and Sarah, if I remember correctly, the takeaway is that trans fats are really, really, really, really bad for you.

    [00:07:02] Sarah: So That's right. It is really, really, really bad for you. Industrial trans fats are a product of partial hydrogenation. Now, if you look online, you'll see loads of information warning you about the perils of trans fats in margarine. However, this information is outdated. In 2007, the World Health Organization put forward a global proposal to reduce these industrially produced trans fats.

    [00:07:27] Jonathan: and we've done a bit of research on the effect of this proposal. And in 2021, 28 countries had mandatory trans fat limits in place, which accounts for about 2.8 billion people, which means the majority of people are living in places where they're, they're not limited. But it does mean that for many of us, if you're listening to this in the US or in Europe, trans fat and margarine is not something that we need to be worrying about anymore.

    [00:07:49] Sarah: Yeah, absolutely right. And in fact, trans fats were actually removed from most foods in the UK and the US way before 2007. I think it's this fear of trans fats in margarines that probably explains this dip that you talked about in the popularity of margarine that we saw in the 1990s. Now, the problem is, Jonathan, so with the removal of trans fat, From the margarines as the hard fat, we need to find another way of creating hard fats that give suitable melting points for margarine. What we need to remember with fats and oils is one of the really important roles they play is their functional role in food. And so by this I mean their melt profile that they confer to a food. So I always use chocolate. It's a great example of this. So chocolate contains cocoa butter. It's the main fat and cocoa butter melts at 37 degrees Celsius and this is body temperature. So when you put the chocolate in your mouth, one of the reason it has that wonderful mouth feel is because it melts as it warms up to your body temperature. The same applies to when we think about margarines and we think about butter. What is it that's special about butter? It's the melt profile of the butter, whether it's used in bakery or spread on your toast. And so what the food industry need to do is try and mimic that with the spreads, which is why it's really important to replace the hard trans fats with another kind of hard fat.

    [00:09:13] Jonathan: So, Could you tell us how they now make margarine, given that the old way they did it, created these trans fats and were so dangerous? How does it happen today?

    [00:09:22] Sarah: So Jonathan, it is done quite differently in the UK and the US and I'd like to just spend half a minute explaining how the processes are different so that we can understand. Why the health effects might also be different.

    [00:09:36] Jonathan: Alright, you, you geek out for a minute

    [00:09:37] Sarah: Okay. So in the US margarine is now made through a process called full hydrogenation, typically using soybean oil. So in the process of full hydrogenation, what happens is, is you change an unsaturated fat to a saturated fat. As we mentioned before, this fat then becomes really, really hard. Now the problem is it's too hard to be spreadable, so what we now need to do is blend it with a liquid oil. We need to blend this fully hydrogenated fat with a liquid oil to give it the suitable melt profile. So what they typically do is take this fully hydrogenated fat and blend it with the original soybean oil, which makes this spreadable fat that can be taken straight from the fridge and can be spread from the fridge. So in the UK. It's a little bit different. And this is because in the UK we think of the word hydrogenation to be unacceptable because it's perceived to be the same as partial hydrogenation, which produces trans fat. So, Even though full hydrogenation doesn't produce trans fats, consumers won't buy a product made in this way. So instead, manufacturers use a process called interesterification. And this is actually what I did my PhD on an an area of research that I'm still actively researching. So if you would give me an hour, I'd love to talk about this, Jonathan.

    [00:11:04] Jonathan: Maybe give us the highlights, Sarah.

    [00:11:06] Sarah: So the process of interesterification changes the structure of the fat molecules, which then changes the melting profile of the fat. Okay. It doesn't change the amount of saturated monounsaturated, it just changes the structure of where the molecules sit within the fat. So that, again, you can have a spread that has the suitable melt profile so that it's semi hard in the fridge and then soft for spreading when you take it out of the fridge.

    [00:11:33] Jonathan: What does this mean in the end, these different processing for sort of the health properties of margarine? Does it end up looking quite similar or is there something you really need to look at? You know, um, is one margarine very different from another margarine

    [00:11:44] Sarah: because of the different ways the margarines are made in the US and the UK? The main difference is that in the US the saturated fatty acid is predominantly steric acid. Um, and in the UK the saturated fatty acids are predominantly a saturated fat called palmitic acid and these behave a little bit differently in the body, which is why it's quite difficult actually comparing US spreads with UK spreads. Although I've just recently completed a study looking at exactly this, looking at the palmitic acid rich spreads in the UK versus the steric acid rich spreads in the US And my study has actually found that there's no difference in the health effects. Between these two spreads when they're fed for six weeks to individuals.

    [00:12:30] Jonathan: We talk about this definition of ultra processed food as something that you can't make in your own kitchen. And what seems to me clear is whether that's the US or the UK, like you cannot make this in your kitchen. This is like really, this is like a chemistry lab. Is that fair?

    [00:12:46] Sarah: It's fair to say you couldn't make this at home. It involves multiple processing steps as well as extracting the oil. There are chemicals that are added in, so emulsifiers, for example, so that it does stick together. Colorants are often used, so that has that nice kind of yellow orange color that mimics butter. And there's some additives that might be added in as well. A lot of spreads though now that a sold do have quite a low number of these ingredients added in an attempt to make sure they are as healthy as possible. But you are correct that we would not be able to make these spreads in a typical home cooking set up.

    [00:13:26] Jonathan: Is it fair to say that in all these examples, margarine will end up being viewed as an ultra processed food.

    [00:13:33] Sarah: Using the current classification system, you are correct. Yes.

    [00:13:36] Jonathan: So Sarah, we, we've indulged you with an explanation of just how complicated it is to make margarine, but I'd love to talk about what's the relative healthiness of these two, and I think that, you know, one of the things that I've learned over the last few years is that the magic of the food matrix and the complexity of human beings means that, You can look at things just in terms of saturated fat or whatever, and actually the impact on humans is completely different. So could you talk us through like the human research studies that can help us to answer this question we started with; what's better, butter or margarine?

    [00:14:14] Sarah: Yeah. So what we would typically do, Jonathan, when we try and look at the health effects of a food, um, and certainly on the podcast when you and I are talking about it, we'd always start looking at population studies, don't we? We always start by looking at, okay, if we're following different populations, over a number of years, how does this food versus that food impact our health? Now, it's really tricky to do this when we are looking at the health effects of butter. Versus margarine. Given that over the last 20 years the composition of margarine has totally changed. So if I was to look at these studies 30, 40 years ago, it would very clearly show, well, margarines are so bad first because they've got all these trans fats. So what we've had to rely on is firstly looking at studies that look specifically at people consuming butter, and then look at randomized control trials that these very tightly controlled studies that feed people. Different amounts of butter and different amounts of margarines and look at how they impact their health. So what we know firstly, is that if you are consuming butter at quite normal level, so not to excess, and we follow you over many numbers of years, it seems to have a very small impact on your health outcome. If you are consuming large amounts, so for example, in Finland, they used to consume up to about 45 grams per day, and that's huge. So a portion of butter, if you think of those little packs, Jonathan, that you get when you go to a hotel or a cafeteria, you know the little sachets you get typically have only about six grams of butter in them.

    But in Finland, people consume about 45 grams on average, and many consuming even more than that a day. Now, in that situation, we saw that rates of heart attacks, strokes, for example, cardiovascular disease were really high, and it was partly attributed to the fact that they have lots of butter in their diet, but they also have lots of other healthy unhealthy components in their diet. Now at that intake, I think it's quite clear that this population kind of evidence shows that, whoa, that's too high. It's not great for your health. Now, if it's at the level of intake that you know, most people in the UK and the US might consume by just spreading it, for example, on their sandwiches are on their toast, then the evidence at that level shows that it's unlikely to have actually any significant long-term unfavorable effect at that low level of intake.

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    And we always need to think, Jonathan, when we talk about research showing the health effects of foods, about how much of it we actually consume, and it's different across different countries. What we do know though, is that if you were to swap from having butter to the kind of spreads that are out there today, these highly unsaturated fat spreads that contain no trans, that actually you will get a reduction in circulating blood cholesterol, so you'll get a reduction in this bad LDL cholesterol. Now these are short-term studies, typically, the longest these are is maybe 20 - 24 Weeks and I think it's really important to, to say that we need to still understand what the long-term impact is of the spreads. Do we actually see over a long-term this favorable impact playing out? And the reason that I caveat this is because there are these other ingredients that we talked about in spread.

    [00:17:46] Jonathan: And I know that if Tim was here, he talks about this, there are a bunch of things in these margarines because they're ultra process that we know has an impact on, you know, the microbiome like emulsifies and we don't understand what the long-term impact of that is. So potentially, I think he would be saying you might be overstating the benefit. because you might see these short term benefits, you're not going to be able to see the longer term drawback.

    [00:18:12] Sarah: Yeah, I think that's a really fair representation of how we need to think about this. And especially for people that have high cholesterol, if you do consume. A reasonable amount of butter swapping to one of these unsaturated, fat rich spreads will have a benefit on reducing your cholesterol. But I think that Tim has a really important point to make is that because these spreads that we are now consuming are relatively new, we need to really try and think about understanding what the long-term health impact is.

    [00:18:49] Jonathan: I'd love just, you know, as we're summing up, share, I guess what I, I'm doing as a result of talking to both you and Tim and other people, which is I mainly use extra virgin olive oil. So, you know, in the past I think I would've cooked quite a bit with butter. I definitely use extra virgin olive oil there for sort of everything that I'm, I'm frying, but also I use it a lot on, you know, if I have toast in the morning and I have toasted rye bread, quite often I pour lots of olive oil over it and that's fine and I use a knife and fork and it tastes fantastic. I've got used to it. And I think that everyone is agreeing that the health properties of the extra virgin olive oil are much better than the margarine. Or the butter. So it feels to me like, you know, to me, part of this answer is I wouldn't go and put margarine all over my food every day, I wouldn't put butter all over my food every day because it adds up. I like that. And then every so often I have, like if I'm out at the restaurant, there's butter, I definitely put it on the bread. It tastes delicious. And I think about that as being like a treat in the same way as other things are a treat and I really enjoy it. I have to say I like the flavor and the taste of the butter. Now that it's something I don't have as often, I actually think I appreciate it more. It's a bit like, you know, you might decide to have a glass of wine. It's like tastes good. Nobody's telling you that it's really gonna be great for your health but you know, life is for living and you know, feeling that nothing should really be off the table, which I know is, is something that we believe a lot and I have been sold on.

    [00:20:15] Sarah: Yeah, absolutely, Jonathan. So I think Extra Virgin Olive oil, without a doubt, is the healthiest fat or oil that anyone could consume. But it takes us back to that point about functionality that we talked about earlier. I don't want to be putting extra virgin olive oil on my toast or my bagel in the morning. I want that lovely, creamy texture. Now, personally, I go for butter because of the creamy texture, the richness of it. If I had high cholesterol, I would probably still have butter just on my toast, but I would avoid using butter, in other kinds of cooking. So I think at low levels it's fine, but I think that what we should be trying to do is find other oils, to cook with where we don't necessarily need that or desire that kind of creamy texture of butter.

    [00:21:04] Jonathan: I think that's brilliant and I think everyone's always really interested in what you're actually doing. Sarah, and I guess the point to leave this is I know that you and Tim are working with a number of other scientists really to work more on this question around ultraprocessed foods to try and understand based upon the latest data with all this new microbiome information, everything, to try and better understand, you know, what is it within ultra processed foods that seems to be really causing the damage that we see and that might allow us to better understand like, you know, actually margarine is maybe not quite as good as we've been thinking, or do we continue to feel good about its you know, relatively high score. I would say if you look for most people within ZOE compared to butter.

    [00:21:44] Sarah: Yeah. Jonathan, I've been teaching undergraduate nutrition students at Kings College London for the last 20 years about the health effects of fat. And I start every lecture by telling them what I'm telling you now might be different next year or in five years or 10 years, which I know can be quite frustrating for listeners. But actually it should be something to have confidence in that we are actively researching all of this so that we can make sure that we give the best, most recent evidence to people.

    [00:22:16] Jonathan: Amazing. Thank you very much, Sarah.

    [00:22:18] Sarah: Thank you for having me.

    [00:22:19] Jonathan: Well, if after all of that you want to know how your body responds to butter and margarine, then you may want to try ZOE's personalized nutrition program.

    [00:22:27] Jonathan: You can learn more and get 10% off by going to joinzoe.com/podcast. I'm Jonathan Wolf.

    [00:22:32] Sarah: And I'm Sarah Berry.

    [00:22:34] Jonathan: Join us next week for another ZOE Podcast.

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