Sugar: How Bad Is It Really?

Hi, I'm Meryl Horne, filling in for Wendy Zuckerman, and you're listening to Science Versus. This is the show that pits facts against fructose. Today, we're looking at sugar. Is it really that bad? Sugar has always been the villain in our diets, that thing calling out to us that we know we should resist. And recently, it feels like everyone's piling on to tell us, don't do it. Sugar is one of the deadliest things you can eat. Our bodies are not able to adapt to the amount of sugar that we're consuming, and it's making us so sick. Every time you eat sugar, every time, it does permanent damage to your body. Sugar is poison, and Americans need to know that. It is poisoning us. That last voice you heard was RFK Junior, the Health and Human Services Secretary in the US, and he's recommended that Americans have zero added sugar in their food. Zero. And things get even more heated when the topic of high fructose corn syrup comes up. We hear that this one is way worse for us than other types of sugar. High fructose corn syrup, where do I f*cking start? Literally cheap garbage with zero nutritional value. Ah, high fructose corn syrup actually has a similar effect to obesity as fuel to a fire. But then at the same time, influencers are telling us that there's a loophole here. Just eat natural sugars. Those are way healthier. So the best alternative is agave. I love good honey. I love maple syrup, the thicker, the darker color, the better. Raw honey has been shown to have a ton of health benefits in many studies. Real maple syrup and why you should be chugging it. We're gonna be chugging the research on all of this. We'll find out whether sugar really does such terrible things to our bodies. And if we really can go to town on stuff like honey and maple syrup. Because when it comes to sugar... Where do I f*cking start? Duh, with the science. Science vs. Sugar is coming up after the break. Welcome back. Today on the show, we're looking at sugar. How bad is it really? This is Meryl Horn, and with me is senior producer Rose Rimmler. Hi, Meryl. Hey, Rose. So you're often the one that covers nutrition topics on our show. Are you like a little mad at me for getting in your lane? No, I don't want to do this. I know. Why don't you want to find out about the science of sugar? Do you have a sweet tooth? I do. I, let's see, every morning, pretty much, most mornings, I put honey on my yogurt. That's what I have for breakfast. And also throughout the day, I eat a lot of fruit. Like, I eat fruit at breakfast. I usually have some fruit after lunch. Well, I have some good news for you right off the bat. Can I keep my fruit? Yes, fruit is totally okay. Yay! That's one thing that some of the sugar haters get wrong, is that sugar overall is not poison, because we know fruit does have a lot of sugar in it, but it's also one of the healthiest foods you can eat. Is that because of, like, the fiber and the nutrients? Yeah, the fiber especially. There's a lot of, like, good stuff in fruit, which makes it healthy to eat overall. So one huge review found that eating more fruit is linked to a lower risk of getting heart disease, some types of cancer, types of diabetes. So that's one reason why sugar is not just terrible for us overall. And another one is that we know that whenever we eat stuff with sugar in it, our bodies do use some of that for energy, right? This is, like, quick source of energy. And that's why, like, you see marathon runners having that, like, sugar goo stuff. It can be converted really quickly into energy, unlike other things like fat. Yeah, like, if I was cycling the Tour de France, I would be like, they could have all the syrup I wanted, I assume. Yeah. So yeah, there is some good here. But for the sugar haters, aren't they not really coming for your, like, fruit? You're more worried about the sugar that gets added to stuff, like soda, cakes, your ice cream. Marilyn, I think you're underestimating the cooginess of people on the internet. They come for the fruit, too. Well, they're wrong. Don't let them do that. But this concept of, like, added sugars being the thing you have to worry about, that's familiar to me. And I think I've seen that for sure online. Like, the whole, like, no-added sugars. Yeah, that's definitely, like, a thing that's out there. That's the big concern, right? So that's what we're really going to dive into. Let's look at whether it does make us gain weight first, since there's this idea that when we eat sugar, it really, like, packs on the pounds compared to eating other stuff. Oh, like, sugar is, like, gram for gram, like, more fattening than other nutrients. OK. And so one of the first studies that shed light on this was done by Professor Jim Mann at the University of Otago in New Zealand. He did it, like, 50 years ago, actually, back in the '70s. But funnily enough, I can remember that study very clearly. Oh, really? Because of the way it turned out. Ooh. And so, yeah, it really stuck with him. Like, a tootsie roll that you left in your pocket too long, because something totally unexpected ended up happening. So here's how it went down. OK. The goal of the study was to see what happens when people replace sugar for other types of calories, like, starch, the stuff that's in bread. So they could see, like, is sugar particularly unhealthy for us? So here's what they told the volunteers. We said, look, we want you to replace-- give up x amount of sugar and replace that with starch to see the effect. So ditch the dessert and have some pasta instead? Yeah, yeah, yeah. So we had a dietitian, excellent dietitian, who worked with these people on a regular basis and highly motivated people. And they said, yeah, well, do everything you say. So my dream of having extra mashed potatoes at the end of the meal? Yeah, exactly. It doesn't sound that bad, actually, right? Like, instead of having sugar, you're supposed to basically have everything else. You can have starch. You can have protein. And they wanted them to do it pretty precisely, like, substitute out one for one. Like, the calories that you're going to have for sugar have the pasta instead. But what ended up happening is that instead of doing that one for one replacement, they ended up eating less overall. So like, oh. So yeah, instead of having, like, the exact amount of calories that they're going to have in sugar and pasta, they ended up having less pasta. They just couldn't get that much starch down their gullets. Yeah, yeah. And so they ended up losing weight. And so Jim couldn't do the thing he was trying to do, which was see, like, which is worse, calorie for calorie. Here's what they would need to do instead. You've actually got to do it in a controlled environment where you actually give people all their meals, and you virtually lock them up to make sure that they are actually not going to change their calorie intake. Right. One of these nutrition studies where you get people to live in the lab, and you give them all their meals. Yeah, basically. My favorite. So yeah, he had to wait for these more careful studies to come along. And they have. Wait, so other researchers have done that since Jim? Yes, yes. Other researchers will do what he was trying to do kind of properly. So like, make sure people aren't actually changing the total amount of calories that they're eating to find out if sugar itself causes more weight gain than other stuff. So several years ago, Jim and his team collected a bunch of these studies for a meta-analysis. They ended up looking at 12 of them. So now we can answer the question, right? So are you ready? Yeah. So what they found is that sugar does not have some sort of magical power to make you gain weight. So if you have people eat the same amount of calories, some of them are getting sugar, some of them are getting other stuff, they generally do not gain more weight with the sugar. I mean, to me, I was kind of surprised because it does feel like sugar is bad for our weight. And it is true that people who have more sugar generally will gain more weight. And that's because in the real world, when people have a lot of sugar, they aren't compensating by eating less of other stuff. Maybe because sugar doesn't make us feel as full as other foods do. I mean, you could see this in Jim's study. And it just makes intuitive sense. Like, if you imagine having a bottle of Coke with your lunch, you're not going to be like, oh, I guess I won't be that hungry for a big lunch anymore because I'm having all this soda. Like, no, you're going to have just as big of a lunch as you would have otherwise if you're having water with your lunch. And so even though it doesn't seem like sugar is magically good at making us gain weight, people do tend to just eat more overall when they have a lot of sugar in their diet. It's magically good at being delicious and making you want to eat more and more of it. Yeah, that too. And so we end up gaining weight. And that could increase your risk for some types of cancer, type 2 diabetes, and cardiovascular disease. And there's another thing that sugar can do that's not so good for us. It's bad for our cardiovascular system. And that actually is true even if you're not eating more calories overall. Sugar seems to be bad for our blood, basically. It's not a huge effect. But it's still like a tick against sugar. And why is it bad for our cardiovascular system? It's because of the way that sugar can get converted into fat. That ends up being bad for us. We'll actually come back to that a little later. But first to complete our roundup of why sugar is bad. So number one, if we eat more sugar, we tend to gain weight. Number two, it's bad for our cardiovascular system. And number three, can you guess, Rose, the other main reason why sugar is bad for us? It's bad for your teeth. Yes, it's a big thing. Sugar gives us cavities. We've known this since the 1950s when there was a really terrible experiment Jim told me about. It was done in Sweden. Most unethical by modern standards. Where they gave people who lived in mental institutions, they gave them, I think, those sort of toffee kind of things to chew and other sweet things. Showed that those people in the mental institution who were given these disgusting, sugary, sweet things, they got terrible dental care. Yes, you can't just give people diseases. But yes, OK, so sugar really does lead to cavities. It's not an old myth, OK? No, yeah. Now we know it's because sugar feeds bacteria that are in our mouths. And that creates cavities, or at least little holes in our teeth. OK, so here's where we are. Sugar is not looking great. So far, lots of the studies we've been talking about are just using basic table sugar. But there are these claims that some sugars are better for you than that, or worse for you than that. And so this opens up a whole can of gummy worms. That's what we'll look into next. Oh, did you bring gummy worms? Discussion? Check your mail, no. Look under your seat. So next up, we're going to tell you whether high fructose corn syrup really is the big bad wolf. Whether honey or maple syrup is the way to go. And the answers might surprise you. That's after the break. Welcome back. Today is sugar day at Science Versus. With me is Rose Rimmler. Hi, Meryl. Next up, we're going to talk about the favorite punching bag in the sugar world, high fructose corn syrup. And the idea that it is way worse for us than other sugar. So this was in the news recently when President Trump praised Coca-Cola for using cane sugar in some of their sodas in the US. And the company confirmed that they're going to do that soon. So of course, all the talking heads wait in on high fructose corn syrup. A lot of folks, I personally agree with this, find high fructose corn syrup kind of creepy. I like cane sugar better because it's more natural. High fructose corn syrup, it comes from corn, but I don't think it remembers what a corn looks like. This is kind of an old one too, right? I mean, this was big in the '90s. I remember this being an issue when I was a little kid. Yeah, that high fructose corn syrup is like particularly bad for us. Yeah, maybe it's a California thing. I don't know. Did it just reach the East Coast? Because in California, we've been talking about this. It's like 1975. So do you get bad vibes from high fructose corn syrup? Everybody in California knows that the vibes are really bad for high fructose corn syrup. But to find out if it's more than just bad vibes, I called up Dr. Kimber Stanhope. She's a research nutritional biologist at the University of California, Davis. And her specialty is sugar. So she's been very popular this past news cycle. Have you been getting flooded by requests from reporters to talk about this right now? Definitely a lot. You're late. I don't know. So there actually is a legit reason why high fructose corn syrup might be bad for us. It's because of the fructose. That's one of the basic sugar building blocks, along with glucose. And at one point, like in the '80s, scientists were thinking that fructose might actually be better for us than other stuff, like glucose. Because fructose doesn't raise our blood sugar like glucose does. So maybe good, especially if you have diabetes. But those glory days of fructose didn't last long. Because pretty quickly, studies started coming out, finding that fructose has its own set of problems. So one big one is that it often gets turned into something called triglycerides. And triglycerides are what fat is made of. So Kimber told me, imagine you got someone who was willing to donate some of their body to science. And then-- You took a big chunk of their fat. Most of that fat is triglyceride. Oh, so it's like the currency of fat in the body. Right, exactly. Does it look like anything under a microscope? Pure oil. So most of your oils at home that you cook with, that is nearly pure triglyceride. Oh. So in the blood, it forms these droplets. And over time, though, these droplets can start stacking up in our blood vessels. They almost sort of round out the edges and look like bricks, but freeform bricks. You like squishy bricks? Yeah, yeah. And that layer of squishy bricks narrows the blood vessels, and that can raise your blood pressure and up the chance of you getting a stroke. OK, so the reason fructose is a bad guy is that it gets turned into triglycerides. Triglycerides cause these fat bricks that can cause all these heart disease issues. That makes sense. But wouldn't that happen with any type of sugar that you eat? Like, why are we blaming fructose here? Would that also happen with glucose or something like that? It can. So it can happen with glucose under certain conditions, but fructose basically gets converted into triglycerides more easily. It's sort of fructose's evil superpower. And so now some scientists think that fructose is worse for us than glucose. But earlier, you said that fruit is OK, and doesn't fruit have a lot of fructose in it? It does, but the fructose in fruit is OK because it's bound up inside the fruit. It's alongside all that fiber we talked about. But with something like high fructose corn syrup, the fructose there is just kind of free-floating. And so there's this concern that that's particularly bad for our bodies. But is it? So Kimber wanted to know what actually happens when you give people the stuff and just compare it to table sugar. So let me tell you about one of the clinical trials she's done. She got 52 adults. And they actually had them move into the wing of a hospital for three days in the beginning of the experiment, where they could run a battery of tests on them. We collect blood all day long. We start at 8 o'clock in the morning, and we go all the way to 8 o'clock the next day, at least every hour. Wow. And this was to check for stuff like triglycerides and cholesterol. They also got liver MRIs done, since some of those triglycerides can build up at the liver too, which is not good. And they basically wanted to get a really good baseline of where people are at before they started giving them any sugar, like everyone had to eat the same food while they were there, like salad. The complaints I got about that salad went on and on. I got so tired of people saying, oh, I can't eat all this salad. Like this much. I mean, it was not an enormous salad. Was it like iceberg lettuce and really bad bland tomatoes, though? She defended it. She was like, no, this was like a tossed salad. So I had tomatoes, cucumbers. Oh. But people did seem to like the next part of the experiment more. They get to go home now, and they get to drink lots and lots of Kool-Aid. Now, what was the Kool-Aid flavor? Was it the fruit punch one? They got to choose. I actually many times stunned the cashiers coming through with easily 1,000 packets of Kool-Aid. Oh, my gosh. Oh, my gosh. You really like Kool-Aid, don't you? But I usually waited for it to be on sale, but-- And the Kool-Aid they got was sweetened with either table sugar or high fructose corn syrup. So that was the big difference between the two groups once they went home, was they either drink a lot of table sugar, sugary Kool-Aid, or high fructose corn syrup Kool-Aid. Yes, exactly. Yeah, they had to have it three times a day, and they didn't know which one they were getting. So now, after 12 days of that, they go back to the hospital again so they can redo all those tests, and now we can finally see how bad the high fructose corn syrup is. So I asked Kimber, was high fructose corn syrup any worse for people than normal table sugar? No. No. There was never a difference, a significant difference between the two. Wow. So what would they have seen if there was a difference? So they're looking for at the triglycerides, like fat in the liver, and you'd expect that if high fructose corn syrup was worse, you would see more triglycerides, more liver fat in that group. But instead, they saw a rise in both groups. But there wasn't a difference between the two. So yeah, I asked if Kimber was surprised. No, I wasn't surprised at all. The results were actually pretty much exactly what I would have expected. She didn't drink the Kool-Aid about high fructose corn syrup. No. Are you? I'm surprised. I don't know. I mean, I guess I am, and I'm not. I know that so much of what we are told about nutrition is BS. So I'm not surprised this thing is BS. But I do have this internal feeling that high fructose corn syrup has got to be pretty bad. And that's interesting that at least on these measures, it was the same as plain old sugar. Yeah. Yeah, I was surprised too. But the reason, once you find out what high fructose corn syrup is, it makes a lot of sense. So I've been kind of holding back on you for dramatic effects. But basically, high fructose corn syrup does not actually have that much more fructose in it than normal table sugar. Really? Yeah, despite the name. But it's just the net, yeah. So basically, both are made out of two things, fructose and glucose. High fructose corn syrup is often 55% fructose. Do you want to guess how much fructose is in table sugar? Well, you told me it's not that much of a difference. So 50%? Yeah. It's half and half. So yeah, they're pretty much on par. So slightly high fructose corn syrup? Yeah. It's in this case, it was slightly higher. And so that's why Kimber also wasn't surprised. That difference is not enough to show up, at least in a two-week study. So it's actually-- it's not like it doesn't deserve its stigma of high fructose corn syrup. No. And others, did I just have to back this up? It's funny. You'd think that if this is the case, the people behind high fructose corn syrup would have rebranded ages ago. Yeah. Because if they could just be like-- if they just call it something else, then they wouldn't have had this whole mess, maybe. They actually tried to. Yeah, there was a campaign where they tried to change it to just corn sugar. But the problem is, when they first invented it, they called it high fructose corn syrup, because the thing that came around first was just corn syrup. And that didn't have any fructose in it at all. So that was low fructose. That was basically no fructose. And then they started adding fructose to it to make it sweeter. And that's why they called it high fructose corn syrup. It's higher than nothing. So it's sort of a misnomer. And sometimes it actually has less fructose in it than table sugar. But I bet, yeah, I think they're probably regretting their decision pretty strongly now to call it that, because now it's kind of stuck. So maybe this is ignorant. What table sugar? That's from beets, cane, sugar cane, or both. Yeah, those are the two main sources, are either beets or sugar cane. And that, in both cases, it's half and half. So 50% fructose, 50% glucose, which, by the way, means that there's no real reason to think that cane sugar is especially healthy for us when it's basically the same thing as high fructose corn syrup when you look at what makes it up. But so does this change your mind? After all, your brainwashing growing up in California about how terrible high fructose corn syrup was, are you going to go put some of that now on your yogurt? Corn-- it's very hard to undo brainwashing. But I do-- genuinely, now my question is, maybe high fructose corn syrup isn't worse than other types of sources of sugar. But does that mean they're all bad? Because hippies like me, we get a little bit of a squeeze of pleasure when we use agave or honey or something instead of high fructose corn syrup. So does that mean the natural sugars, they're just as bad as high fructose corn syrup? Well, that's what we're going to look at next. So let's start with agave syrup. You'll see this in fancy coffee shops. You can get it in your smoothie. But I couldn't find that much research backing up this idea that agave deserves this wellness glow-up. So there's barely any research on it in humans at all. And when you look at what's in it, it's mostly fructose. Around 85% of agave syrup is fructose. Oh. Huh, OK. Agave is more fructose than high fructose corn syrup. Yes. Yeah, interesting. Yeah, and some scientists argue that fructose might not be that much worse than glucose. But a lot of studies say that it is. So I don't see any good reasons to go for agave specifically. Oh, OK. All right. Unless it's been turned into a tequila. All right, so let's look at maple syrup next. There's some buzz online about how that one's healthier. And there is a particular trial that comes up a lot. And at first glance, it looks like maple syrup is healthier. Like, you know, when you kind of skim the paper, it looked like they saw a difference between people who were eating maple syrup and people who were having table sugar. Like the maple syrup group had less fat around their bellies. So I asked Kimber about that study. I can't tell you how unimpressed I was by that study. So the reason she's unimpressed is that these researchers did dozens and dozens of tests looking for differences in, like, health markers between the group which got the maple syrup and the group that got the normal table sugar. And out of those dozens of tests, only three showed a difference. And they turned that into, wow, maple syrup is healthier. But any statistician will tell you, no, wait, that's within the odds of random chance. Right. You do that many, many studies. And some of them will happen to turn up positive, especially when their p-values are, like, 0.047 for one of them. Good for you. Oh, my God, Maryl, I'm so impressed. You said that. You know exactly what I'm talking about. Yes, exactly. Yeah, OK, that's classic. If you run a lot of tests, some of them could come up showing a positive effect, even if it's just by chance. Yeah, and like, they could have done some work to, like, correct for the fact that they were running so many tests, but you don't see them do that in the paper. And on top of that, the study was also funded by a maple syrup group in Canada. Oh, I was going to say, yeah, I was going to say, it's like the Canadian mafia was, like, behind this, the Canadian maple syrup mafia. I mean, it's basically a group of maple syrup producers. I did reach out to the authors of the study about these criticisms and didn't hear back. But yeah, this was the most impressive study I could find on maple syrup. So I think it's delicious, but I don't think we have good evidence that it's healthier. And then you mentioned honey? Yes, my go-to sugar. OK, well-- Oh. Don't ruin my breakfast. No, so it does seem more promising to me, actually. So like, there is a big review that came out recently that looked at all the trials that have been done on honey. And overall, it looked like there was a benefit with the honey, like multiple studies saying that people's cholesterol looked better than in the sugar, like the table sugar group, for example. And some of the studies found a benefit, specifically when they were giving people so-called raw honey or, like, unprocessed honey. Oh. OK. But when I talked to Kimber about this, she was, like, more positive than she was with the maple syrup. But she did see some flaws in those studies, too. Like, most of them didn't blind the people in them. So they knew that they were getting honey. And she thought, you know, maybe if people knew that they were getting this, like, supposedly healthy, you know, raw honey, then they'll do other healthy stuff, too. And the review pointed this out, too, saying that at least a dozen of the studies in their review had this issue. So overall, I asked Kimber, bottom line, what's-- if you're trying to decide what to put on your yogurt, should you pick honey over maple syrup or, like, brown sugar? Possibly, yeah. But I would forgo it completely and learn to put fruit on. But is it-- do you think-- Because there's a little bit of evidence that maybe it's better for, like, certain things. It's worth substituting it in? It is questionable enough that if I was forced to make the decision between natural, unprocessed honey versus sucrose or any other form of sugar, I would pick the honey. If someone had a gun to your head and was like, Kimber, you must add one of these things to your yogurt, you would choose the honey. That's how you'll have to phrase it. OK. So Rose, how does that make you feel about your honey? Well, here's what I would say. By adding some honey to this slop that I make, the honey makes me more likely to eat these other things that definitely have a lot of nutritive value. Like, I have plain Greek yogurt, lots of protein in there. And I do put fruit on it, Kimber. But it's still kind of sour, depending on the fruit. And I'll put some nuts or nut butter. I feel like she'd give me a gold star for all that. And if adding a table sweet of honey on that gets me to chow down on that every morning, I feel like it's probably OK. But maybe not. I don't know. Yeah. I mean, that brings us to this bigger question of, like, overall, should we be feeling guilty about having some sugar in our lives? Like, Kimber is sort of a stickler when she says, you know, you really shouldn't have any added sugar. But other scientists are like, oh, no, a little is OK. So let's look at what the World Health Organization says. They focus on something called free sugar. This is basically the sugar that's added to stuff. And so they recommend that you don't have more than 10% of your total calories be made up of this sugar. And research backs this up. Like, one big study I found looked at how much sugar people ate, and then their risk of dying from cardiovascular disease. And you can see the risk of death starting to creep up around this 10% mark. Oh, risk of death. OK. So 10% of your daily calories is not, like, that intuitive. Can you give me something I can really sneak my teeth into? Yeah. So for someone who has 2,000 calories a day, that 10% comes out to 50 grams of sugar. So, for example, a can of Coke has about 40 grams of sugar in it. So that would be most of your sugar budget right there if you had a can of Coke. Or you could have, like, three chocolate croissants. That's roughly 50 grams of sugar. Well, because they only put that little negative chocolate in there. Yeah, it's not actually that much. But that still made me feel better. So you're signing three croissants. Yeah, I still have my three croissants. Some other issues there. So to me, I was like, oh, that's not too bad. So I talked about this with Jim Mann, since he actually helps the world's health organization come up with that 10% recommendation. Does that mean I can have, like, a cupcake? Like, what does that mean? Can you have a cupcake? Sure, you can have a cupcake. But if you have a cupcake, then don't have something else. I mean, I had this morning with my coffee, I had some cheesecake because there's a certain bakery in this time that makes very good cheesecake. And my daughter happened to produce some cheesecake from this bakery. And I absolutely enjoyed it. But I mean, I've made a mental note before we had this conversation without even thinking, well, that's my dose for the day. And I enjoyed it, and it was really good, and it enhanced my well-being. But I certainly would not have a dessert tonight. But you didn't feel guilty about having that slice. No, I didn't feel I certainly enjoyed it. Yeah, that's reasonable. I mean, a full disclosure, I had a piece of cake before jumping on this call. I made a cake over the weekend. Before I told you the science of how bad sugar is. It just gobbled it down. Then I had honey on my yogurt. So I'm actually probably over budget today, but I'm definitely not going to have any more sweets the rest of the day. So I like his approach, yeah. Yeah. Well, thanks, Rose. Thanks, girl. So we have 60 citations in this episode. If you want to look at any of those, read more about sugar science. Then check out our transcripts. The link is in the show notes. And the last citation is a special treat, a link to an episode of Science Versus that was made 10 years ago. That was also one sugar. This episode was produced by me, Merrill Horn, with help from Rose Rimmler, Michelle Dang, and Aketti Foster Keys. We're edited by Blythe Sorrell. Mixed in sound design by Bobby Lord. Our executive producer is Wendy Zuckerman. Fact-checking by Sam Lemonick. Music written by Peter Leonard. Bobby Lord, So Wiley, Emma Munger, and Bumi Hadaka. Thanks to all the researchers we spoke to, including Professor Barry Popkin, Dr. John White, Dr. Nick Fuller, Professor Paul Breslin, Dr. Richard Johnson, and Dr. Vasanti Malik. Science Versus is a Spotify Studio's original. Listen for free on Spotify or wherever you get your podcasts. And if you do listen on Spotify, follow us and tap the bell for episode notifications. We'll fact you soon. [MUSIC PLAYING]