What's the deal with artificial sweeteners?

12:11Emily Oster:Okay. Is it possible that people with like subclinical esophageal problems drinking the same temperature tea would perceive it as hotter because it's like, oh, I've got an irritated esophagus already and like it kind of burns more as it goes down. So I'm going to answer this survey and say it's hotter even if it isn't. Am I reaching too much here?

12:33Perry Wilson:Maybe. I think you're reaching a little bit and this is what we call a perspective study. So they have these surveys and they follow people over time. So it's like not quite a subject to that as you might think if you like surveyed people in the moment and asked them this question. I think the more important thing for people to understand is this is a very, very rare cancer. So this isn't, you know, this is a sort of medium size increase in the risk of cancer on a very low base rate of this cancer. Esophageal cancer is just not a very common cancer. So even if you did change this behavior, and even if we thought these estimates were causal, the sort of potential reduction in your cancer risk is very, very small.

13:11Perry Wilson:So my guess is for most people, this is sort of not decision relevant, but it's an interesting example for me of kind of an observational study where I think there's more potential weight, but something we'll never get a randomized data on because it's too rare and the behavior is too ingrained.

13:30Emily Oster:But you know what? Iced coffee, delicious. Nothing wrong with that.

13:34Perry Wilson:I hate iced coffee. Iced coffee is like a nightmare. I think that's totally wrong. I think you're a hundred, like I couldn't disagree with you more.

13:41Emily Oster:That's a hot take. Listeners, please tell us who's right about iced coffee, me or Emily. This is a slam dunk for Perry.

13:47Perry Wilson:It's like hot coffee in the morning. It's like iced coffee. It's like, what is this?

13:53Emily Oster:Okay.

13:54Perry Wilson:Yep. Last question. There have been some new headlines about a new designer drug showing up in a San Francisco autopsy. Is it the next fentanyl?

14:06Emily Oster:This is really sad.

14:08Perry Wilson:Yeah.

14:08Emily Oster:This is a drug called cyclorphine. And, you know, I think the thing a lot of people that aren't in this space don't realize is a lot of people when they hear about opiates, opioids, drugs that bind the opioid receptor, things like morphine, heroin, et cetera, that cause obviously untold suffering in the US and around the world. Most people still think like, oh, yeah, but you need these poppy plantations, right? You know, in Afghanistan or whatever to get the raw materials. And like that's at least a rate limiting step. That is not true. Nope. Nope. So synthetic opioids like fentanyl are really coming to dominate the market.

14:43Emily Oster:These are things you can synthesize in just kind of any lab, like any minimally equipped lab with some relatively common raw materials. And cyclorphine is yet another one of these. I think the thing that's scary about cyclorphine, number one, is it's probably quite a bit more potent than even fentanyl, which is of course like a hundred times more potent than heroin. So we don't have precise date on this because it's a relatively new drug. It only showed up in Europe in 2025. And I think this case in the US is the first death from cyclorphine in the US. This was a teenager, by the way, I think a 16 year old kid, unfortunately.

15:21Emily Oster:Cyclorphine might be about 10 times more potent than fentanyl, which means like an amount that would be very barely visible to see could be a lethal dose. And of course, people aren't necessarily taking it because they even think it's cyclorphine. They may believe they're taking heroin. They may believe they're taking a Percocet or something like that. And this stuff is added to give the high, but because it's so potent, minor miscalculations on dosage get you into a potentially fatal situation. The other thing that some people are worried about is that naloxone, which is the opioid reversal agent.

15:57Emily Oster:Many people, including me, have doses of naloxone around just in case. It's not a terrible idea, but it may require higher dose. Because this is such a potent opioid, it may require higher doses of naloxone to fully reverse if someone is overdosing. So it's definitely scary and something that needs to be monitored.

16:23Perry Wilson:Next week, I think that we should have only positive things in our health news. And I think people should also consider themselves lucky that I didn't make us discuss the Hydrox diarrhea incident in today's health news. I'm so thankful for that. You're welcome. That's it for the health news of the week. And now, what is the deal with artificial sweeteners?

16:47Emily Oster:All right. A while back, Em, we got a question from a listener who was like, I'm paraphrasing. I might not get quite, but it was basically like, I love Diet Coke, but I am worried about these artificial sweeteners. Is it healthier to drink a Coke than a Diet Coke? Yes. And are you saying yes, that we had that question or yes, that that's the answer? Yes, we have that question.

17:12Perry Wilson:No, that's not. No, I'm not answering it. But yes, we have that question.

17:16Emily Oster:Yeah. I think that more than anything else exemplifies like why we need to talk about the artificial sweeteners, because there is so much scary stuff out there that the whole the whole reason we have artificial sweeteners is because people like, oh, well, sugar is not good for you. Like sugar is bad. And here's an alternative, you know, that doesn't have calories and is therefore better. And people are so nervous about artificial sweeteners that they're actually like, well, for that whole use case, I don't even care about because the dangers are so high.

17:45Perry Wilson:People also really love Diet Coke. So, you know, like Gen Z calls Diet Coke a fridge cigarette, which I think is so right. It's like you take it out of the refrigerator in a can. It's like cold and you open it in that first sip. It's like it's sweet. It's not too sweet. And it's like fizzy. Like I Diet Coke, it's like there's just nothing like that, you know, for those.

18:06Emily Oster:Do you remember RC Cola? Are you old enough to remember?

18:10Perry Wilson:I really, really am a devotee of Diet Coke. I was not an RC Cola person.

18:15Emily Oster:Hot take, RC Cola is the superior cola. Bring it back.

18:18Perry Wilson:What I'm saying here is that this is important to people's lives. This question is important. And there are actually a lot of fears that people express. But I think in some ways, like the most interesting one is the question of whether Diet Coke makes you fat. and whether artificial sweeteners are in fact also making you fat. So why don't you just have, you know, regular sweetened soda if they're both going to be linked. And a super interesting feature is that in the observational data, that is definitely true. So people who drink more artificially sweetened beverages consistently, we see associations with higher obesity rates, higher type 2 diabetes across large cohorts, millions of people.

19:01Perry Wilson:That is very, very established as an association in the data.

19:07Emily Oster:But people aren't coming to us for associations. They want some causality. They want some causality. And we'll get into that. But before we talk about the observational data and the problems with observational data here, we should talk about plausibility even first, right? You can observe data, but you want there to be some plausibility. And I will say as a lover of the laws of thermodynamics, that I really do believe that fundamentally changes in weight are driven by the difference between calories you take in and calories you put out, calories in, calories out. Now, I know it's not that simple.

19:49Emily Oster:That's like someone saying like, well, you get rich by earning more money than you spend. And like, well, that's technically true. Like it doesn't really encapsulate everything. I know it's a bit pat, but when it comes to sucralose, aspartame, we'll talk about all the fun artificial sweeteners in this episode, these give you zero calories. So if we're going to say that they cause an increase in weight, they must do something to bring in other calories in some other way, right? Because it can't be them in and of itself or can them? Can it? Right.

20:24Perry Wilson:No, it definitely can't. That's not how that works. I think the two things that are sort of mucking around in the background of some of the wellness discussion here are one, the idea that in some way, these chemicals, you know, change your microbiome in a way that is going to then impact your absorption of calories in some way. And there's a fair amount of hand-waving there, but because we don't really know anything about the microbiome, we don't understand it that well, I guess that could be true. And then I think there's something else about kind of sugar tolerance, like sort of sweetness tolerance that impacts things in some other way.

20:57Perry Wilson:But fundamentally, it doesn't really make any sense because the way that our body, for the most part, gets calories is by consuming them. And if you consume something that doesn't have any of them, you're not consuming them. And so that doesn't really make any sense.

21:10Emily Oster:But I do believe that like, yeah, I think sugar tolerance is a thing. Emily, you told me that I should not be sweetening my coffee as much. Sugar tolerance is a thing. And I know my kids like sweet things and I do sort of wonder like, okay, if they had less sweet things, maybe they would like sweet things like fruit as opposed to sweet things like Kit Kats.

21:33Perry Wilson:Maybe. But I will say, I think in general, the kind of claims about diet soda that people make that are really difficult to track with just the reality of the world is this idea that it's just the same, to have a Coke or a Diet Coke, right? Like that those things are somehow equally contributing to weight. And that's just very hard to imagine that that's true. And yet we have these very persistent associations, which brings me to why I think artificial sweeteners are like an incredible example for statistics, which is that this is a place where we have very clearly the two fundamental problems with learning causality from observational data.

22:16Perry Wilson:And I'm going to tell you what they are. Okay, here we go.

22:20Emily Oster:I'm ready. Tell me. Number one, reverse causality.

22:25Perry Wilson:So people begin to consume diet sodas because they would like to lose weight. Okay. This happens in many places, but it definitely happens here that people who are interested in losing weight because perhaps they are struggling with obesity will start consuming diet soda. And so then you observe out in the world, you know, the people who are struggling with obesity are more likely to consume diet soda, but it's that the weight is causing or the illness or whatever it is is causing the diet soda consumption rather than the other way around. So that is what's called reverse causality. You see this like everywhere.

23:05Perry Wilson:So, you know, people who take baby aspirin are more likely to have heart attacks, even though baby aspirin protects you against heart attacks, because we tell people to take baby aspirin when they have already had a heart attack.

23:20Emily Oster:Yeah, yeah, yeah. The medical researchers often call this confounding by indication, right? Like you have an indication to take a baby aspirin, and that's the confound there. But I like reverse causality better, because economists' terms are always easier to We're winning there.

23:35Perry Wilson:Yeah. The second problem, which you call residual confounding and we call omitted variable bias, is that the people who are consuming Diet Coke are ex-ante even before any of the other behavioral confounding or just ex-ante different. Yeah. So this is a lifestyle marker. We tend to see consumption of artificial sweeteners is associated with less education, with lower income. That's just what you see. And that seems to be driving. I think it's also associated with smoking and less physical activity and all kinds of other variables which contribute to health. And my sort of favorite set of facts here, and I actually confirm this by running the data myself yesterday in preparation for this episode, is that this varies with different kinds of sweeteners.

24:24Perry Wilson:So if you think about the space of artificial sweeteners, and we're going to talk about the different kinds of sweeteners, but we have like sucralose, aspartame, which are kind of like the baseline, like the old school regular sweeteners. Yeah. And then we have stevia, which is like the Prada of artificial sweeteners. Fancy. Fancy sweeteners. And it turns out if you look in the data at like who consumes those, about 53 % of Stevia consumers have a college degree versus about 30 % of consumers of other – so it's like Stevia is like it's consumed by people who have a lot of other positively selected features.

25:04Emily Oster:Every product category has a bougie component apparently.

25:09Perry Wilson:Stevia is the bougie artificial sweetener. And then it turns out if you looked in the observational data, stevia is not associated with an increase in weight, whereas the other artificial sweeteners are. And I think that kind of closes the book a little bit here on this kind of like, like, it's not the artificial, none of these things have any, like, they're all sweet. None of them have any particular, you know, calories in them. It's just who is consuming them. And I think those combination of middle variable bias and reverse causality are driving a huge share of what we see in this space.

25:40Emily Oster:I think it can certainly explain what we see in the observational literature, which again, is consistent associations between intake of these things and a higher BMI and diabetes. But what we like to do to actually prove one way or another is to do a trial, right? Like let's randomize some people. And, you know, it goes without saying you can't do randomized trials of 10 million people to find tiny effects and things like that. But we do have some data, I think, that we can speak to that would at least, you know, suggest whether the observational data is completely backwards or not. Emily, so broadly, yeah, I agree.

26:23Emily Oster:The observational data showing a link between artificial sweetener consumption, BMI, diabetes could very easily be explained by reverse causality and omitted variable bias. But, you know, maybe it's also true, right? Like these things exist and they push things in that direction. But nevertheless, maybe there is some effect here. And it seems to me like the best way to settle this, as always, is to do a randomized trial, right? Do we have data where we take some people and give some of them artificial sweeteners and some of them not artificial sweeteners? And broadly speaking, what happens when you do that?

26:57Perry Wilson:Yeah, what happens when you do that is people lose a little bit of weight. And we have some trials on that in adolescents, although largely they're just replacing sugar-sweetened beverages with water. But when we generally replace sweetened beverages with artificially sweetened beverages, people lose a little bit of weight. These trials tend to be pretty short. people lose a couple of pounds. It's not like an earth shattering change in everything, but it does seem consistent with what you would expect that removing 250 calories a day from people's diet causes them to lose some weight, which is pretty much what you would expect in the kind of calories in calories out story.

27:35Perry Wilson:I guess I think this for me is like answers this core question people have at the top and the question we started with, which was like, should I substitute a regular Coke for my diet coke no don't don't do that you don't you shouldn't do that don't drink calories yes don't drink your calories sometimes it's good to drink your calories but in general don't drink your calories if you're worried about your weight don't drink calories how about that

27:58Emily Oster:if you're right otherwise it's fine training for a run yeah yeah a great ultra if you're on in the

28:03Perry Wilson:middle of an ultra and i think another way to say it's like if people are in the middle of an ultra marathon like they drink coke they don't drink diet coke and that is because it doesn't have any sugar on it. It doesn't give you the glucose that you need to complete the rest of Western states. Having said that, that is actually a fairly narrow version of this question. I think there is a much broader version of the artificial sweetener question, which gets into, like, how does sweetness work? And also, are there other concerns about this? And I guess that's, you know, beyond the, is this going to make me fat?

28:40Perry Wilson:I think there's a question of, like, is this going to give me cancer? Like, am I just putting some random, you know, you told me at the cold open that like, you know, I'm, these things are so difficult to process that they're using them to track sewage. Like it doesn't seem good. And so I think that's where we should turn. Yeah.

28:56Emily Oster:Absolutely. And the, the story of how some of these substances came about is another example of where a lack of good regulatory oversight and, and honestly outright corruption got into the very DNA of this stuff and has persisted in the form of conspiracy theories ever since. And we're going to tell that story after the break.

29:27Perry Wilson:Hey, our ride's almost here. Are you ready? Just grabbing my shoes.

29:31Emily Oster:That's what you said 10 minutes ago.

29:33Perry Wilson:I just dropped a video call, uploading this giant file on my tablet, looking at my watchgo bananas with the group chat, and, of course, still lining up tonight's playlist on my phone. All at once? Yep, story of my life. That's why I switched to T-Mobile. They have the fastest 5G network.

29:50Emily Oster:Okay, multitasker. I see you.

29:53Perry Wilson:Honestly, I never imagined I could do all this at once. It's awesome. Say no more, I'm totally switching. My post is taking way too long to upload. That's a sign you've got to get T-Mobile. So many reasons to join T-Mobile. Find yours at T-Mobile.com.

30:16Emily Oster:Fastest based on analysis by UGLO Speed Test Intelligence data of national speed score results incorporating 5G download and upload speeds for the first half of 2026.

30:26Perry Wilson:I had a huge body flare-up again, was itchy from head to toe, and I applied to topical steroids like I normally do when I'm in moments of crises like this. You know, I normally wait about 30 minutes, and I'm like, okay, so this is not working. And so I applied again and waited another 30 minutes, and I'm like, this is not going down. What is going on here? And that's when the anxiety kind of kicked in because I was like, what is happening? My entire world and idea of what it was to manage my eczema at that time completely crashed. That's when I started doing research for the first time. And then I realized, wow, I think the medicine stopped working for me.

31:14Perry Wilson:And my body was just going through maybe a withdrawal process.

31:17Emily Oster:This is Skin Queries. Listen on the iHeartRadio app, Apple Podcasts, or wherever you get the stories that make you feel understood.

31:47Emily Oster:Star Trek First Contact on Weird House Cinema on Friday. Listen to Stuff to Blow Your Mind on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts. Okay, we are back talking about artificial sweeteners, and it's time to do a little bit of science and explain how this stuff actually works. Um, so taste is really an amazing sense. And, um, you have a bunch of receptors on your tongue that do certain jobs and they communicate via nerves to the brain and your brain interprets those signals to give you a sense of how things taste. And that's really all there is to it. You have, for example, a sour receptor that basically is just a hydrogen channel.

32:32Emily Oster:So hydrogen is what is present in acids, things that are sour. and if you put a bunch of acid in your mouth, the hydrogens go through that channel, stimulate a nerve. Your brain says, ooh, acid, I'm going to interpret that as sour, and that's sour. You have a salt receptor, saltiness, which does the same thing but with sodium. So if you put a bunch of sodium in your mouth, your brain says like, oh, that is salty. But sweet is a bit more complicated. It's a protein-based receptor. Actually, it's two proteins that come together in a protein dimer. And when something binds this protein, it opens a channel that allows actually calcium to flow in.

33:09Emily Oster:There's always calcium sitting around. And that's the sweet signal. And that's what sugar does. That's what sucrose does or fructose or anything. They all bind this channel. That's all well and good. And then, you know, like any other receptor in your body, you can design chemicals that bind that receptor in their own way, right, and activate the receptor in their own way. But basically none of the artificial sweeteners were designed to do this in any way. They were almost all discovered accidentally. Can I just run through? Because I think it's hilarious. Like the history of artificial sweeteners is the history of bad lab hygiene.

33:49Emily Oster:Like what not to do.

33:50Perry Wilson:Like work hygiene. Just like bad hygiene.

33:54Emily Oster:Terrible. So we'll start with saccharin, which was invented in 1879 by Guy Constantine Fahlberg. He was working on coal tar derivatives, I guess, back in 1879. That's the kind of thing he did. And he was at dinner and his hands tasted sweet as he was licking his fingers. And he was like, oh, that's odd. Boom. They had discovered Chaffron. Wash your hands, people.

34:14Perry Wilson:Wash your hands.

34:15Emily Oster:Wash your hands.

34:16Perry Wilson:But if you don't, you could discover a very important chemical.

34:18Emily Oster:Yeah, right. Aspartame. Or you could get sick. Aspartame 1965. 1665, James Schlattler was trying to synthesize an anti-ulcer drug, and he licked his finger to pick up a piece of paper. He did that guy like, oh, and he was like, oh, that's very sweet. And that gave us aspartame. Sucralose, 1976. Shashikant Fadnas at Queen Elizabeth College in London was working with some colleagues, and they had created a chlorinated sugar, and apparently his colleagues asked him, can you test this? He heard, can you taste this? And he tasted it. It was very sweet. I just think this is hilarious, but people don't do this.

35:07Perry Wilson:Like, this is what I don't understand. Like, do you just like, you tasted some sweet stuff on your hands at dinner and then the next day we were like, oh, I'm not dead. I guess probably I should market that. Put it in a drink. I mean, yeah.

35:19Emily Oster:No. Yeah. They do animal testing. They do stuff. They do studies. Well, with the aspartame, we got to get to the aspartame story. But just one last thing because it's so fun. Have you ever tried miracle fruit pills? Absolutely.

35:33Perry Wilson:My kids once made me try this.

35:35Emily Oster:Oh, my God. We did it with my kids. So do you want to explain how it works?

35:41Perry Wilson:I don't. This was a long time ago.

35:43Emily Oster:Well, not the chemistry. I'll do the chemistry, but just the experience, right? So you get these pills in the mail and you sort of like dissolve them in your mouth.

35:50Perry Wilson:And then after, yeah, so you dissolve them in your mouth. And then for some, like what I recall being quite a lengthy period. Like an hour. Not like two minutes, but like a sizable amount of time, you could just like eat a lemon and it was delicious. Yeah.

36:03Emily Oster:Yeah.

36:03Perry Wilson:And any kind of bitter, I mean, it's like any kind of sour, sour thing would sort of taste sweet.

36:09Emily Oster:Totally. It's really cool. And people have these like miraculin, it's called miraculin, miraculin parties where they just have, yeah, they have like pickle juice and lemon juice and all these kinds of things. And they just taste amazing. Or like a Guinness tastes like a milkshake basically. But the chemistry is so cool. So the way miraculin works is it binds that sweet receptor on your tongue, but it doesn't activate it. So it doesn't actually taste sweet itself when you dissolve in your mouth. It just sits there and it binds pretty strongly, which is why it lasts for like an hour. And then if the pH in your mouth goes down, Like you put an acid in your mouth, the chemical, the miraculin changes its shape on the receptor and opens the receptor.

36:48Emily Oster:So by putting an acid in your mouth, all of a sudden your sweet receptors are like, ooh, that's sweet. And your brain, like your brain doesn't know, right? It's like, oh, that's sweet. Now the sour receptors still work. Like miraculin doesn't bind that at all. So for instance, when you're drinking lemon juice on this stuff, you still get the sour signal, but you also get sweet signal. So it kind of tastes like lemonade. It's not just like pure sugar. It's really fascinating. But actually people have like hurt themselves by putting so much acid in their mouth, like drinking vinegar and stuff like that.

37:19Emily Oster:It all tastes sweet that like they can get little mouth ulcers and things. So don't go crazy, but it is kind of fun.

37:24Perry Wilson:That is. It is very fun. It's something your kids will really like.

37:28Emily Oster:Yeah. All right. Aspartame is – because you were talking about how we get from accidentally like licking my fingers instead of washing my hands to a world where we're concerned about, are these things causing cancer or any other horrible scenario? And the truth is the aspartame regulatory process was bad. Bad. It was bad. And this is bigger in Europe. I feel like in the US, you don't hear people talking too much about aspartame. It's like, oh, we got to get aspartame out of the system. It's huge in France, for example. It's a very big sort of issue, the aspartame thing overseas. But I think this is why.

38:13So Em, do you want to walk us through the crazy stuff that happened to get aspartame approved by the FDA? Okay.

38:26Perry Wilson:In 1974, aspartame is discovered by Searle and it is quickly approved by the FDA, like very, very, quite quickly. Yep.

38:38Emily Oster:Thumbs up. Sounds good. Let's go.

38:40Perry Wilson:Thumbs up. It's great. And then there is a freezing of the approval because people are concerned, consumer attorneys are concerned about some related compounds causing brain tumors in mice. So this idea that these are cancer-causing things kind of comes up. And then the FDA starts investigating. And actually, it turns out the animal testing was quite poor. And they actually start requesting a criminal investigation of the company, suggesting that they may have submitted false test results. So they may have actually done the testing and then sent, or maybe they didn't do the testing and they just made things up.

39:14Emily Oster:Yeah. This is a big, this does not happen. I mean, criminal investigations of pharmaceutical companies are very unusual in this country. And so, you know, this seems pretty bad, right?

39:28Perry Wilson:What happens next is even worse. OK, keep going. So then the U.S. attorney who is investigating this quits the government and he moves on to a different job. Where is that job?

39:41Emily Oster:Where did he decide to take a job?

39:43Perry Wilson:He took a job with Searle. Yeah, weird. The investigation kind of stalls out. They get to the statute of limitations. And this sort of just for that period goes nowhere. Then what happens?

39:58Emily Oster:Yeah. The FDA did, you know, there was some pushback here for obvious reasons, right? You had the lead prosecutor leaving the government, working for the people he was prosecuting. The case had died. The FDA to sort of mollify the public put together an independent panel to review the aspartame data. And they basically said, look, we're going to recommend against approval of aspartame until there's more brain tumor data. Now, to be clear, everyone up front, there will be no more brain tumor data. Like, it doesn't cause brain tumors. That data eventually comes out and has been replicated ad infinitum in multiple other studies.

40:34Emily Oster:But at the time in 1980, that wasn't clear. So, you know, this was a reasonable thing, but I don't want to say just because people were worried and asked for more data means that it's true. It's not. But okay, so the FDA panel says no. A year later, Ronald Reagan appoints Arthur Hayes as the FDA commissioner, and he takes that FDA panel recommendation against aspartame and overrules it. Just, you know, the FDA commissioner can do that, says, thank you for your work panel, but nope, aspartame gets approved. He would later leave the FDA to join a public relations company. Do you want to guess what pharmaceutical company was on that company's client list?

41:15Perry Wilson:Yes, it was Searle. It was Searle, wasn't it?

41:17Emily Oster:It was Searle. So this is all gross. This is like classic government corruption, you know, revolving door nonsense at the agencies. All that being said, like, it's actually not aspartame's fault that these humans are gross and corrupt, right? Like, it's don't blame the molecule, blame the horrible people. And again, there's potentially nothing more deeply studied in the nutrition literature than the potential toxicology of aspartame since this time. Like, it really has gone through the ringer. It does not appear to cause cancer or anything like that. But because of how it got started, there's this narrative.

42:00Emily Oster:And I will say that one thing that really set the narrative on fire actually didn't happen until 1998. So long after all this, aspartame has been approved for a while. We actually had the follow-up studies that the FDA had originally requested, looking for brain tumors, not finding any, and so on and so forth that appears to be safe. And then we get a chain email, which like this is 1998, before the days of social media, called the Nancy Markle email. And according to the email, and I'll tell you what it says, but I want people to think through how much this stuff echoes what we see now on Instagram and TikTok and stuff from influencers, because it's like the exact same beats.

42:43Emily Oster:Okay. So the email says that this was taken from her talk, Nancy Markle's talk at the World Environmental Conference. The email claims that aspartame causes multiple sclerosis, lupus, chronic fatigue syndrome, seizures, brain tumors, Alzheimer's disease, blindness, birth defects, and deaths. Some versions of the chain email were modified to add Gulf War syndrome. Like, okay. It has a lot of scientific jargon. It reads like an Instagram post.

43:12Perry Wilson:Oh, 100%. It's like, do you know a study show? You know, da-da-da-da-da. Like, you know, there's music over it in my head.

43:19Emily Oster:Yeah, 100%. The letter says that while she was giving this talk, people were standing up and saying, like, that's me. Like, like, I've been affected by aspartame at this at this major scientific conference, which is the sort of old and day equivalent of like, and then everybody clapped. Right.

43:36Perry Wilson:It had so many likes, so many people like likes and comments. Exactly.

43:41Emily Oster:Now, Nancy Markle does not exist. Neither does the conference. That's never been found. The reporters have suggested the email was written by an activist named Betty Martini. She refers to herself as Dr. Betty Martini, but just a note here that it's an honorary doctorate in humanities from an unaccredited religious institution. Another wellness trope referring to yourself as doctor, when maybe not exactly. Sure. So anyway, that's a bit of the aspartame saga, which I think just – it reminds me a little bit when we talked about Lyme disease and how there are a lot of conspiracy theories about Lyme disease now, and a lot of them are traced back to the sort of bad way that doctors treated the early patients before they understood what Lyme disease was.

44:30Emily Oster:And it's like somehow the origin of these substances or these diseases, like, stay with us for decades and lead to where we are.

44:39Perry Wilson:I think the other sort of trope that works here that echoes a lot of other wellness stuff is the kind of discussion of chemicals and the like scariness of chemical interactions. So people will tell you, you know, something which is true, which is that aspartame is a dipeptide and it's held together by a methyl ester. And if you break it down, you get aspirate, you get phenylalanine, you get methanol, and that's toxic and it converts to formaldehyde. and oh my God, this is basically just like drinking a can of formaldehyde. And that's, you sort of work through that. That's true. But of course it's like in tiny amounts that are very similar to the amount of methanol you get from a diet soda.

45:23Perry Wilson:Is it quite similar to what you get from like a fruit juice? Like you can process some formaldehyde.

45:32Emily Oster:No, totally. So methanol, like if you've ever brewed at your own alcohol, like brewed beer.

45:39Perry Wilson:And who hasn't? I have.

45:42Emily Oster:Definitely. When you distill alcohol, like the yeast don't only make ethanol, they make methanol too, which is why fruit juice has a little bit of methanol and a little bit of alcohol in it. When you're actually distilling that out, you have to be careful not to include the, you have to get rid of the methanol. That's like part of what an actual distillery does is get rid of the methanol and only keep the ethanol. But yeah, all fruit juice has a little bit of methanol in it just to put some numbers on it. If you were to break down all of the aspartame in 12 ounces of diet soda, that would lead to about a 20 milligram methanol intake.

46:18Emily Oster:A typical alcoholic drink has about 35 milligrams of methanol. Fruit juice, fresh squeezed before yeast have a chance to do anything, has about 15 milligrams of methanol. If you let it sit for a few hours, you have about 30 milligrams of methanol. So yeah, the dose makes the poison. We say this all the time. Your body has ways to, things in very high doses can be toxic that in low doses just aren't because that's the natural world. Like we evolved to process some methanol because we eat fruit and other things that ferment.

46:50Perry Wilson:To pull this together, like despite these initial concerns, despite the corrupt nature of the aspartame approval, there is no evidence that artificial sweeteners cause cancer in people. There's like in rats, there are a few studies which have suggested that if you exclusively feed rodents, artificial sweeteners, maybe there could be some problems, although even those studies, I think, have some pretty significant limitations. And again, when we get to the sort of dosing issues, like we are talking about doses that are vastly, vastly, vastly, vastly higher than people could ever consider, even people who really, really like Diet Coke.

47:37Emily Oster:Yeah. You know, some people listening might know that saccharin got a warning label in 1977 about bladder cancer. It was subsequently removed in the year 2000. But it's interesting if you look at where that came from. So they had given mice just Herculean doses of saccharin and male rats formed saccharin crystals in their bladder that irritated the lining of the bladder that like kind of damaged the epithelium of the bladder, which increased the risk of bladder cancer. It was actually only seen in male mice. It was not seen in the female mice. It was actually species specific too, like it didn't happen in other mice.

48:13Emily Oster:It's very unique to like the kidney and urinary system of this particular mouse that it just forms saccharin crystals. This doesn't happen in people, which is why the label was removed because it's just, it's not a human risk. But if you have this particular species of mouse, please don't feed it exclusively saccharin water, which I think is what was done with this study.

48:36Perry Wilson:Great, great point. All right. So that is all of the like regular artificial sweeteners that we talk about. And one of the features of almost all of these is that the doses are really, really small. That we're basically giving people teeny tiny doses because these things are very sweet. They really, like these chemicals, you know, touch something at your lab, you lick your fingers, they're really, really sweet. Way sweeter than sugar.

49:00Emily Oster:Oh, yeah. Hundreds of times sweeter in some cases. Yeah.

49:02Perry Wilson:And so the third thing that I think we want to touch on here is actually there are artificial sweeteners or sugar alcohols that actually do, you do have to consume quite a lot of to get the same effects. And this is a place where I think there maybe are maybe some reasons to be a little concerned.

49:26Emily Oster:I think that's right. And I think we should bring it back to dose. I want to talk about dose for a second and why, in principle, I get more nervous when we're talking about relatively higher doses of any substance versus relatively low doses of a substance. So, so, all right, no one is eating 30 grams of aspartame, right? 200 milligrams of aspartame in a Diet Coke. So getting 30 grams, you're, I can't do that math, 100, 100 cans of Coke or something like that, 100 cans of Diet Coke, but a single serving of keto ice cream can get you 30 grams of erythritol, no problem. Okay. So we're talking, and the reason you need so much sugar alcohols, things like, by the way, xylitol, erythritol is probably the most common one that you'll see.

50:12Emily Oster:Maltitol, lactitol, they all end in that atol. They're just not that sweet. They're actually a bit less sweet than sugar, about 70 % the sweetness. And so you really need to put a lot in, whereas with things like aspartame or sucralose, you put a tiny pinch in. And the reason this matters -

50:29Perry Wilson:Why are people using the, like, why not sweeten your non-sweetened? These are like commonly used in like keto ice cream. Why not just stick in some Stevia and that shit?

50:41Emily Oster:Some of the non-nutritive sweeteners, the high potency non-nutritive sweeteners aren't heat stable. I know that. I think sucralose is actually though, but maybe sucralose is expensive.

50:52Perry Wilson:I mean, I often wonder if some of this is, by the way, people are like, oh, I don't want to have sucralose because I love this other thing, which seems fancier. Yeah.

51:02Emily Oster:And I mean, some of the stuff they can label as like natural because they get it from plants or things. But the reason I worry more about eating 30 grams of something than 200 milligrams of something is, especially when it comes to this, these molecules, the high potency ones are designed to bind that receptor on your tongue. They do that. That's their job. And they do it extraordinarily well. because you're getting such a tiny dose, the chance of them also binding something else and like doing something else, what we call off target effects is just slightly lower, not zero, but they're designed with high potency towards one receptor.

51:44Emily Oster:It makes it slightly less likely that they're going to muck around with other things. When you're taking a hundred times the dose, 200 times the dose of a sugar alcohol to bind that same receptor. Well, the chances that it can also do other things because there's so much of it around, just it's higher. So I do just out the gate, worry a little bit more about the effects of the sugar alcohols in principle. But before we go to the real biology, the clear effects are the gastrointestinal.

52:16Perry Wilson:Okay. So I'm going to interrupt you here because there was someone who worked for me for a while, who we got to talking because, you know, work on health and so on. And it's talking about constipation. She was like, this is not something you have to worry about. All you need are these sugar-free gummy peach slices. You have a bag of those. And like, if you are ever constipated, just keep a bag of those and you're all set. And that's true. That's really true.

52:50Emily Oster:It is true. So the sugar alcohols are broadly not absorbed. So they go into your intestinal tract and they don't get absorbed by it. Some of them do a bit, but because there's so much of them, like the number of grams you're taking is high. There's enough in there to suck water into the intestinal lumen. We say they're osmotically active, right? So they suck water in. It's like those packets that they put those drying packets in like pill bottles and stuff like that, right? So they suck water in and that passes through you. And I found some quotes on the Amazon reviews for the Haribo sugar-free gummy bears.

53:38Emily Oster:I think these are maltitol containing for what it's worth. Can you pick one or two of these? Because I was dying reading these.

53:47Perry Wilson:these should come with a hazmat suit and a formal apology to your plumber i ate the whole bag i am now typing this from the bathroom my life has changed i am a different

53:59Emily Oster:person than i was 20 minutes ago um a gummy bear shaped i like this one a gummy bear shaped vessel for pure unadulterated intestinal warfare so be careful is what we're saying it's like it's like

54:14Perry Wilson:fiber, but very fast.

54:18Emily Oster:Yeah, absolutely. Okay. Again, this is coming from the fact that you have to eat more of them to get that same sweetness. There is some concern about erythritol and like, I'll be honest, these are small early studies, but just to say it out loud, there's some concern that erythritol levels are either associated with or potentially causative of a higher risk of blood clots. There's a nature medicine study in 2023 of 20 healthy volunteers. So this is a crossover study where they were randomized to glucose intake, just regular sugar intake versus erythritol. And they measured thrombosis potential, like how quickly the blood would clot given a stimulus to clot and platelet reactivity, which is how quickly platelets clump together, giving a stimulus to clump together.

55:08Emily Oster:And in both cases, they found that erythritol exposure increased the propensity for those blood clots, which is, yeah, small study, but.

55:17Perry Wilson:Yeah. I mean, you always have to be careful when there are 20 volunteers because, and when there's a surrogate endpoint, which means, you know, we're looking at platelet activity, we're not looking at actual health outcomes. There's like a lot, there's many steps between that and sort of genuine concern. I think, you know, the more practical nature of like some of these things really will affect you right now is probably worth knowing.

55:44Emily Oster:Yes. And they will certainly affect your GI tract. About erythritol, I was looking through my closet, my food, my pantry, and I found that we had monk fruit sweetener, like artificial monk fruit sweetener. And I was like, okay, monk fruit is a high potency sweetener. It's called mogricide. It's about 150 to 250 times the potency of sugar. So it's like the others, harder to find, and I imagine fairly expensive. But I looked at my monk fruit sweetener and the number one ingredient was erythritol. So the thing said monk fruit and the number two ingredient was monk fruit extract. And I guess you can just say that it's monk fruit sweetener because there's like some monk fruit in it, but actually it was just erythritol.

56:34Emily Oster:So I was getting like the sugar alcohol when I wanted some, you know, funky, bougie, high potency sweetener.

56:40Perry Wilson:It's perhaps a good point to make that these fancy sweeteners, stevia, monk fruit, which I think people view as like natural and bougie are also very highly processed. It's not like the stevia is just, it. Like it is true that's a plant with like a, it's like a slightly sweet, like you can actually eat a piece of the stevia plant and it's like slightly sweet. But to get from that to the like stuff that you, you know, put in your coffee is like quite an extensive processing procedure. So I don't know. I think people should just be a little less fancy. Yeah. I mean, you're just,

57:17Emily Oster:you're, you're, you're throwing your money away on some, some fancy marketing.

57:21Perry Wilson:Just get some sweet and low, my friend. it looks like.

57:26Emily Oster:Saccharin has a little bit of an off-target binding to the bitter receptor. So in high doses, that's why saccharin has that kind of funky aftertaste, which something like sucralose doesn't have. I use Splenda in my coffee, as you know, Emily, because you've chastised me about having sweetness in my coffee. But you don't like iced coffee either, so I don't think your coffee opinions are valid in my worldview.

57:51Perry Wilson:Yeah, that's fair. I don't like the taste of artificial sweeteners very much except for Diet Coke.

57:59Emily Oster:I think if anything comes out on top, it's Diet Coke in this episode. Not an ad, everyone.

58:04Perry Wilson:This episode should be titled, like, what's the deal with Diet Coke and why is it the most delicious?

58:10Emily Oster:All right, Em, I think it's time. Smash or pass? Artificial sweeteners.

58:17Perry Wilson:I'm a smash. I mean, I think that it's not a health food, but it certainly isn't something people should be afraid of.

58:27Emily Oster:Yeah, I'm a smash. I think I'm going to stand by if you're worried about weight. Drinking calories is just too easy of a way to get too many calories into you. But maybe we should be aware of like sweetness overload and train yourself to like some things that aren't so tasty and sweet. All right.

58:46Perry Wilson:That's it for artificial sweeteners. Your mailbag question of the week after the break.

58:54Perry Wilson:Hey, our ride's almost here. Are you ready? Just grabbing my shoes. That's what you said 10 minutes ago. I just dropped a video call, uploading this giant file on my tablet, looking at my watchgo bananas with the group chat, and, of course, still lining up tonight's playlist on my phone. All at once? Yep. Story of my life. That's why I switched to T-Mobile. They have the fastest 5G network.

59:17Emily Oster:Okay, multitasker. I see you.

59:19Perry Wilson:Honestly, I never imagined I could do all this at once. It's awesome. Say no more, I'm totally switching. My post is taking way too long to upload. That's a sign. You've got to get T-Mobile. So many reasons to join T-Mobile. Find yours at T-Mobile.com.

59:43Emily Oster:Fastest based on analysis by Ookla Speed Test Intelligence data of national speed score results incorporating 5G download and upload speeds for the first half of 2026.

59:53Perry Wilson:I had a huge body flare-up again, was itchy from head to toe, and I applied to topical steroids like I normally do when I'm in moments of crises like this. You know, I normally wait about 30 minutes, and I'm like, okay, so this is not working. And so I applied again and waited another 30 minutes, and I'm like, this is not going down. What is going on here? And that's when the anxiety kind of kicked in because I was like, what is happening? My entire world and idea of what it was to manage my eczema at that time completely crashed. That's when I started doing research for the first time. And then I realized, wow, I think the medicine stopped working for me.

1:00:41Perry Wilson:And my body was just going through maybe a withdrawal process.

1:00:44Emily Oster:This is Skin Queries. Listen on the iHeartRadio app, Apple Podcasts, or wherever you get the stories that make you feel understood. Hey, this is Robert Lamb. And this is Joe McCormick, and we're the hosts of the Stuff to Blow Your Mind podcast. This week on the show, it's Star Trek. So we're going to be talking about the Borg all week long. Are you ready to get some probes put in your flesh? That's right. Tune in. Resistance is futile. We're going to talk science, the culture of the Borg, various interpretations, and we're going to talk about Star Trek First Contact on Weird House Cinema on Friday.

1:01:18Emily Oster:Listen to Stuff to Blow Your Mind on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts.

1:01:26Emily Oster:Hi, Emily and Perry. This is Ezekiel Henze from Des Moines, Iowa. I've heard that sitting all day will, like, kill you. So does that mean that standing won't? Is the standing desk worth the investment? Thanks a lot. Love the show.

1:01:41Perry Wilson:So I will tell you, I did have a standing desk at my last office. And it was really hard to get because it was in a university. And when you want to get a desk that's like different from the other desks that one gets, it's like 4 ,000 bureaucratic layers. And I finally got this standing desk. And then my husband would come in every day and be like, why isn't your desk in the standing mode? And I think I stood up like one time in my entire, like, I just couldn't, you know, I had to put it up, whatever. It was like, I feel stupid. Do you have a standing desk?

1:02:13Emily Oster:I don't. What I have, which is I think the equivalent, is I have a stationary bike that has a platform on it where you can put your laptop or papers. And I was like, this is how I will stay fit. And what I'm looking right now, I have - Is there like clothing all over it? I have a jacket. I have my white coat, my Dr. White coat sitting there. I don't, yeah, it does not get used. I mean, the data actually does suggest that the use of standing desks decreased sedentary time. And we do know that more sedentary time is linked to worse health outcomes. And I think there's some causality there, honestly.

1:02:54Emily Oster:You know, your heart rate's up, your muscles are tensing a little bit more when you're standing, but it's not a replacement for real exercise. And it does require you to actually use the damn thing.

1:03:04Perry Wilson:Yeah, I think this is a good example of a place where the kinds of people who are adopting and using standing desks are already like 95 % of the way towards doing enough exercise and so on. And so it's a sort of a different question than like, if someone were literally sitting all day, would they benefit from doing some standing or some walking? Like, absolutely. If you are like not getting any physical movement, getting some, any amount more physical movement is really good for you. And if that involves just sitting and standing from your chair so you stand up to the desk like that's great the idiots who are purchasing standing desks like me or are approaching like i don't know sitting cycle work things like you are like already kind of doing some exercise and basically everything is is fine and you're the

1:03:49Emily Oster:last person who needs a standing desk i don't need a standing desk i don't need a standing desk i

1:03:53Perry Wilson:don't my daughter asked me the other day about those like walking pads you know where it's like under your desk and and you're walking like could like is that better than than a standing desk i I was like, I don't know.

1:04:03Emily Oster:Stay tuned for the next question of the week. All right. That's it for us today. Stick with us next week. We're doing our first ever grab bag of wellness nonsense. I'm so excited. It's going to be fun.

1:04:14Perry Wilson:Can't wait.

1:04:18Perry Wilson:Wellness Actually is produced in association with iHeart Media. Our senior producer is Tamar Abishai. Our executive producer at iHeart is Jennifer Bassett. Our theme music is by Eric Deutsch. And our content is for educational purposes only.

1:04:33Emily Oster:If you like the show, help other people find us. Leave a rating and review on Apple Podcasts or your podcatcher of choice. And help us spread the word about the show. You can follow us on Instagram at wellnessactuallypod. And don't forget, we want to hear from you. Head over to wellnessactually.fm and leave us a question for our mailbag. Or suggest a topic for a future show.

1:04:54Perry Wilson:We'll let the influencers have the last word. Lydia, oh Lydia, say have you met Lydia? Lydia the tattooed lady How are you feeling? Kind of under the weather? Like you've got the flu? That would be the ricin I gave you I slipped it into that stevia crap that you're always putting in your tea I'll pick up Well, goodbye Lydia

1:05:36Perry Wilson:This is an iHeart Podcast. Guaranteed human.