What's the Deal with Fluoride?

Perry: [00:00:01] Em, are you doing any traveling this summer?

Emily: [00:00:03] We did some traveling, but now I'm just around, uh, around Providence. How about you?

Perry: [00:00:08] We are headed to Italy shortly. I'm very excited. First time I've ever been there. It's a dream. Lifelong dream. Um, but when my family travels, there's this one thing that happens, like a week beforehand. And that, for whatever reason, is my children panicking about is it safe to drink the water? And I think this started, this is probably my fault because we went to Morocco on a family vacation once and I was like, oh, you know this, you know, there's maybe not the best water. And I bought these, um, like lifestraw water bottles. So you could put, you know, these high tech filtered water bottles. And we all had one and they were expensive. And now the kids are convinced that water everywhere will kill you. Do you guys worry about this at all when you travel?

Emily: [00:00:55] Uh, no. Not in. So that's not in Europe.

Perry: [00:00:59] It's a Wilson [00:01:00] neurosis.

Emily: [00:01:00] There are places I would not drink the water, but I would never carry a water straw. You know, those are for like, when you're in the, like in the woods. And it's like the water is full of like Giardia. Those are not for like your Europe. Those are not for European vacations. It's not the marketing.

Perry: [00:01:16] It's not when I'm drinking water fresh from the alpine streams of Lake Como or whatever. I was thinking about this because we're talking about fluoride today and in many parts of the world, not Europe and not the United States, but in many parts of the world. Whether the water is safe to drink is a very reasonable question to ask. And there are obviously many millions and millions of people living in the world who don't have access to clean, safe drinking water. And I was thinking about that in sort of the like, we're very lucky here in the United States to have a broadly safe water system. Not everywhere. Flint, Michigan, I see you, it's okay. But like, you know, broadly speaking, standards in place. And yet despite that, we can still have [00:02:00] an incredible debate about whether the water is poisoning our children.

Emily: [00:02:03] I think in a way, it's because of that, because actually it is only when everything is basically going pretty good that you are able to argue about things that do not matter at all, or only matter a little bit in either direction.

Perry: [00:02:18] Uh, well, arguing on the margins. If there's nothing else that summarizes the Wellness Actually podcast, that is it.

Emily: [00:02:25] That is it. That is it. All right, let's get into it. I'm Emily Oster, I'm an economist and a data expert.

Perry: [00:02:33] And I'm Perry Wilson. I'm a medical doctor.

Emily: [00:02:35] It's Thursday, August 13th, 2026. And this is Wellness, Actually.

Perry: [00:02:40] Because you're getting a staggering amount of health and wellness information nowadays from every source imaginable. And some of it is awesome.

Emily: [00:02:48] And some of it is, well, actually bullshit. Fortunately, we're both people who know how to read studies, how to parse the data, and can tell you what's worth thinking about [00:03:00] and what you can safely ignore.

Perry: [00:03:02] But before we dig in a note that this podcast is for educational purposes and should not be construed as medical advice. We don't know your unique situation, so talk to your doctor for personal health decisions.

Emily: [00:03:13] This week we're asking what's the deal with fluoride? Perry and I will give the official smash or pass, and then we'll get to your question of the week. But first let's do the health news roundup after the break.

Perry: [00:03:36] And we're back with the health news of the week. Emily, we've got some interesting information about this weird flavored vapes decision. And for, for constant listeners of the Wellness Actually podcast, you'll recall that in an episode a while back, we were talking about the rumour of the impending firing of FDA Commissioner Marty Makary. [00:04:00] He was then subsequently fired. That's the wellness, actually. Kearse well described. But we had speculated there was weird stuff going on regarding his potential firing and flavored vapes. And let me just play you the clip from that episode.

Emily: [00:04:15] It seems like some of the reporting suggested that part of the problem is he has been unwilling to follow through on some of the requests of the administration, including a request to approve fruit flavored vapes. Uh, he didn't want to approve fruit flavored vapes because it seemed like they would be appealing to children, which seems right to me. But the administration wanted fruit flavored vapes, and I think they have now been approved.

Perry: [00:04:43] Uh, yeah, that seems like just not a great idea. And also, like, what a weird thing for the white House to lobby for just like So, Emily, new information has come to light, and I thought maybe you could tell us what [00:05:00] we know now was going on behind the scenes in this bizarre decision for the FDA to authorize flavored vape sales.

Speaker 3: [00:05:08] So there's a lot more.

Emily: [00:05:11] Going on here, I think, than perhaps we initially recognized. Ron Wyden, who's a top Democrat on the finance Committee, has now launched an inquiry. I think that's the favorite thing of the that's what the Senate and representative. That's what they love.

Perry: [00:05:24] To have inquiries.

Emily: [00:05:25] They love inquiries. But Kennedy had sent him a letter and basically a pro tobacco super PAC made a large donation to a Trump aligned super PAC about $5 million. Then everyone met, presumably in a smoky room, because it's the tobacco industry at Mar a Lago. And then after that, Trump called Kennedy, Oz, and FDA Commissioner Marty McCarey and told them, we don't know what he told them. But immediately afterwards, the flavored vapes were approved. And so it it [00:06:00] seems like someone paid for this. That's my that's my read. That's with my tin hat on. Someone paid for this.

Perry: [00:06:05] Yeah. I mean, the hat. Also, I want to point out that this was such a strange decision from FDA, which, you know, and Marty McCarey and RFK Jr. Who, you know, are many things, but not really tobacco promoters in any way. And flavored vapes, just to say it out loud, make vaping easier and more attractive to children. That's the major. That's the major issue with it. Apparently, Marty McCarey at FDA had been very resistant to approving flavored vapes. That's what we were talking about. And now we know. Nevertheless, they were approved. And now we know that, uh, I'll make one correction according to, uh, widens letter to Kennedy, Trump called RFK jr. Mehmet Oz, and Marty McCarey at the meeting. Not after the meeting. At the meeting, while the tobacco execs were there at Mar a Lago. So it certainly feels like a hey, we need to authorize flavored vapes type of [00:07:00] thing. Don't know that for sure, but it does explain a bit of a mystery that we were curious about on a prior episode.

Emily: [00:07:07] Wonderful. Getting to the bottom of all kinds of things and finding the bottom is even worse than one.

Perry: [00:07:12] Lower than you.

Emily: [00:07:13] Imagined. Lower. All right, next up, we've got a new executive order about vaccines. There's been a lot of discussion about vaccines. This is something that RFK Jr and Trump appear to be aligned on their feelings that vaccines aren't their favorite. Last winter, RFK Jr tried to introduce a new vaccine schedule by just saying what it should be. This is not the typical approach that has been struck down by the courts, along with many other things that they've tried to do. But now Trump has issued an executive order that calls for a smaller number of childhood shots. Spacing them out more. And he's made some comments. I'm just going to play the clip of his feelings about this.

Trump news clip: [00:07:57] At one year, you should have five [00:08:00] separate visits for vaccines rather than getting them all in the same day. And I saw this early on, and I've seen proof of it where they have a vaccination thing, looks like the size of a bottle of soda poured into a little child's body. And bad things happen in many cases, in too many cases, because this is an explosion. This is an epidemic.

Emily: [00:08:24] All right, Perry, what do you think?

Perry: [00:08:27] Uh, I know I've said this before, but I don't like how people can just say things that aren't true. I know, it's like I'm so naive to think that we should expect our public officials or people on Twitter or influencers to cite their sources or, or, you know, have a basis in fact for what they're saying. It is obviously false that babies get a Coke bottle worth of injections. Uh, they get a couple of milliliters, you know, drop volumes. Like I [00:09:00] don't I don't know what he's talking about. There's other inconsistencies in this executive order. I mean, he says, oh, we should split up the MMR vaccine. Okay. First of all, there is no company or individual measles and mumps and rubella vaccine that does not exist. So so someone has to now, I guess, make that he's also calling for kids to have five individual pediatrician visits to get these separate vaccines. You know, presumably, like how difficult is it to access health care in the country to begin with? And all of this language of like, oh, this is giving parent parental choice, right? This is like, you know, you want the measles, but not the mumps. And you want the rubella, but not the measles Vaccine. This administration and I don't try to get political here, but when it comes to issues like this, it's very clear that they are anti-public health. Like as a concept. They are incredibly pro individualistic. [00:10:00] It's a hyper individualistic political movement, which is why there's resistance, you know, to any kind of top down, like here's the vaccine schedule. Everything should be, you know, you can do what you want, you can do what you want, you can do what you want. But the, the central thesis of public health is that there are certain things that we kind of have to do broadly, because if we don't, it doesn't work. And it's not just vaccines. It's, you know, it's adding iodine to salt. It's like all of this stuff that has changed the landscape of diseases over the century. And it's like getting thrown away. It's very frustrating. Sorry.

Emily: [00:10:36] It's very frustrating.But I actually think there's a, there's another piece of this for me, as someone who spends all their time talking to parents, which is that it's it's not that parents come away with this feeling empowered and like, you know, now I can choose which vaccines I get. You know, people come away feeling confused. Yeah, they're confused and they don't actually want, by and large, the responsibility of [00:11:00] evaluating what is the set of vaccines that are that I need. People have other stuff to do. That is why we have expertise for evaluating which vaccines are safe and recommended, based on a trade off of costs and benefits to those vaccines, and that is why we came up with an original vaccine schedule. It's very frustrating.

Perry: [00:11:18] It's frustrating. I just also want to say there's no new data. Like, like, of course we're data people. It's one thing if it's like, oh no, we, we did this big study and now there's a, we have to change things. That's at least then we can evaluate. There's nothing new here. There is no sign of danger. Neurodevelopmentally from the current vaccine schedule. There's no evidence that combining measles, mumps and rubella versus separating. It makes any difference in childhood outcomes. There's it's it's it's nothing. It's just the whims of the administration, as far as I can tell. Yeah. And it'll hurt kids, which is not.

Emily: [00:11:54] It'll hurt kids. Nice kids, which is bad.

Perry: [00:11:56] All right, I gotta I gotta calm down. So, um, the [00:12:00] the thing that's going to calm me down is. Emily, you can tell me why the tour de France is, um, going to outlaw padded bras. Well.

Emily: [00:12:12] It's it's much better than that, so. Okay, the tour de France is a bicycle race, and there is a female tour de France. It's called the tour de France Femmes avec Zwick. It's very. Zwick is a sock company, I believe. And they sponsor this race. So you have to say the whole name.

Perry: [00:12:30] Big big sock, big sock, big sock.

Emily: [00:12:33] They're in bed with big sock. But an issue that they're having is that apparently when you are biking in a time trial. It's very important to be aerodynamic, and one of the things that enhances your aerodynamics is to have, like more bulk on your front. I have no idea why this would be. I don't know enough about cycling, but you like it's like otherwise, actually, it's like otherwise it's more like a sail. I think it's a bit like for, for listeners of [00:13:00] our very first episode, it's a bit like the penis, the penis thing and the ski jumpers, I think. But like the opposite.

Perry: [00:13:05] You need a padded penis to fly further in a ski jump.

Emily: [00:13:09] Anyway. Uh, so people, there's an incentive to like bulk yourself up. And apparently there's an accusation that some of the riders in the tour de France Femmes were wearing bras that were too large, possibly padded, I don't think stuffed. But like, you know, instead of wearing a B cup, you put like on a D cup bra and like the padding is in there to make themselves more aerodynamic. So then people were saying, okay, we're going to have somebody check, like when before you get on, someone's going to like check out, make sure your bra is not too big. But then other people felt like, hey, we need an elderly Frenchman checking the bras of all the female cyclists. That seems a little awkward. So we've sort of it kind of died. Died there.

Perry: [00:13:47] Yeah, it probably should die there.

Emily: [00:13:49] It's a delight.

Perry: [00:13:50] But it is.

Emily: [00:13:52] But I like this because it's an example of like, what of the sort of almost like wellness, like what's too far, right? If you're at the point [00:14:00] where you're like, I'm going to put a really big bra on to go faster. Like it's, you're taking it too far.

Perry: [00:14:05] I hot take, I think actually a lot of this stuff, including some of the banned supplements and things like that, actually don't make any difference. And it's just sort of, you know, they're like.

Emily: [00:14:17] It's all in your head anyway. Maybe it's like a.

Perry: [00:14:18] Cautionary banning things.

Emily: [00:14:20] Yeah. Or you put on your big bra and then you feel like, ah, now I've got my big bra. Like I'm going to go super fast and my cool TT bike.

Perry: [00:14:27] Uh, well, I sure am going to put on a big bra next time I go.

Emily: [00:14:30] Totally.

Perry: [00:14:31] Big boob energy. All right, that's it for the health news of the week. Um, what's the deal with fluoride? Oh, boy. Emily, this is a controversial topic. We're going to make some people mad.

Emily: [00:14:47] For for some, for a, you know, for a thing that is about municipal water supplies. I can't believe how much people care. You know, like, did you have on your bingo [00:15:00] card? People would be like, I really want to discuss the details of our municipal water supply.

Perry: [00:15:05] I mean, I think they care because of the classic like, but what about the children? Right? Like if you can attach any, whatever your pet issue is, like attach it to the children, like it's going to do better. This is not new concerns about fluoride. Um, and I've got to play you just a brilliant clip from Doctor Strangelove water.

Dr. Strangelove: [00:15:29] That's what I'm getting at. Water. And as human beings you and I need fresh, pure water to replenish our precious bodily fluids. Mandrake, have you never wondered why I drink only distilled water or rainwater and only pure grain alcohol? Have you ever heard of a thing called fluoridation? Fluoridation of water?

Dr. Strangelove: [00:15:55] Ah, yes, I have heard of that, Jack. Yes, yes.

Dr. Strangelove: [00:15:59] Well, do you know what it [00:16:00] is? Do you realize that fluoridation is the most monstrously conceived and dangerous communist plot we have ever had to face?

Perry: [00:16:10] That was Peter Sellers and Sterling Hayden playing general Jack D Ripper from Doctor Strangelove. Do yourself a favor. If you haven't seen it and see it. It is absolutely hilarious and dark and wonderful. Jack D Ripper essentially starts a nuclear war because he's paranoid about fluoridation of the water supply. So this has been going on for a long time. This is not a new theory or conspiracy theory. And, you know, we need to sort of dig in, I think, broadly speaking, to why it's there in the first place and then maybe the concerns about it.

Emily: [00:16:48] Yeah, I think it's worth like, let's just start with, you know, your municipal water supply. It is not just beautiful alpine spring water, like you will be drinking on your vacation. There are many, [00:17:00] many things that we add to water.

Perry: [00:17:03] Yeah, I am really acutely aware of this because I'm a nephrologist. And nephrologists do dialysis, where you run blood through a machine and it cleans the blood, and the water that runs on the outside of the dialysis membrane generally comes from municipal water supplies. And we have to be very concerned because anything in that water supply can get through the dialysis membrane into the blood. So we get very panicked about stuff, and we do a lot of things to treat the water supply before we use it on a dialysis patient. So a brief list of things that are in your water. Aside from fluoride, chlorine, monochloramine, chlorine dioxide those are all to kill bacteria. People don't complain about chlorination of water very often. Orthophosphates and polyphosphates to prevent pipe corrosion, sodium hydroxide and acidic water, sulfuric acid, and alkaline water, you've got to get the pH right. Aluminum sulfate as a flocculant to get all the little pieces of dirt and things to precipitate out. Potassium permanganate to precipitate out iron oxides [00:18:00] so you don't get rust colored water. So there is a lot. And nobody is going to town halls demanding that we no longer chlorinate the water supply, because if we stopped doing that, everyone would get bacterial infections and die.

Emily: [00:18:16] Yeah, I think what what does differentiate fluoride from these other things is that fluoride is not there to clean the water and to make it so you don't get poop diseases from it. It is added because we think it is good for people's teeth. Basically, we can get more into that, but it's added as a kind of this is something to benefit you as opposed to without this, your water will make you ill.

Perry: [00:18:42] Yes, that's that's a great distinction.

Emily: [00:18:44] It seems more optional. No one is interested in fighting about chlorine because if you took that out, we'd all be really sick.

Perry: [00:18:51] It seems more optional. And also there's the psychological. Like something is being done to me. Um, even though you're ingesting the chlorine from [00:19:00] the water and the potassium permanganate from the water. Like the intention isn't there, I think is what you're saying. And there's something about the intentionality of fluoride that gets people's hackles up more.

Emily: [00:19:10] Yeah, that's my that's my feeling. Although it's hard to get inside people's, it's hard to get inside people's head. And, you know, could we generate a bunch of panic about something called orthophosphate? Like probably that doesn't sound good. So maybe that'll be our next episode.

Perry: [00:19:26] Yeah. What about the children's being exposed to author.

Emily: [00:19:28] About the children and the pipe corrosion or whatever? Okay, so before we get into the details of this, let's talk about why we how we know that fluoride is good and where this initially came from.

Perry: [00:19:45] It's such an interesting story. So the history of fluoride in medicine goes back to 1901. And Doctor Frederick McKay, who was looking at a condition which was called Colorado Brown stain from Colorado [00:20:00] Springs, Colorado. These were people that had brown stains on their teeth. But McKay made the insight that they actually had a really low rate of cavities. Like the teeth kind of were ugly and had these brown stains on it, but they just didn't get cavities. It was not entirely clear what was protecting them until 1931, when H.V. Churchill at Alcoa used Spectrographic analysis to determine what was in the water at Colorado Springs and discovered it was fluoride and the levels of naturally occurring fluoride. There were very, very high about 13.2 parts per million in the brown stain affected areas. We're going to talk a lot about like the dosage of fluoride in the water. So it might be worth just like, let's just set the stage now and I'll try to give round numbers, but like ten parts per million. This sort of Colorado brown stain is a lot. The target in fluoridated water is 0.7 parts per million. So [00:21:00] like a 10th of that. Um, and one of the key insights is that fluoride will protect teeth without causing stains at low doses. And then it can sort of cause white stains fluorosis at about 3 to 4 parts per million. And then like really excessive fluoride can cause these brown stains. Once you get up to like ten parts per million or so. Okay, so in 1941, 42, that's when they sort of did the dose finding study to figure out that low doses of fluoride would be protective of teeth. And then 1945, the first community water fluoridation happened in Grand Rapids, Michigan.

Emily: [00:21:32] And I just want to pause. I want to pause you on the because I think one one thing that's worth saying is, well, how did you know? How do they know about the dosing here? And the answer is that there is a fair amount of naturally occurring variation in how much fluoride there is in water across space. There are parts of the world, China, India, where actually the fluoride levels in water are very high. Obviously, Colorado Springs is very high. There's also variation in other places. So many people live in areas where the [00:22:00] naturally occurring water fluoride in the water is higher. They use that to figure out basically how that relates to teeth health.

Perry: [00:22:08] It's such a good point. And when community water fluoridation happens there, they're not adding just like a random amount. They're they're getting the level up to 0.7. Basically. 1945 Grand Rapids, Michigan is the first community water fluoridation at one part per million, a little higher than we do today. Muskegon was sort of a control community nearby, and compared to Muskegon, cavities went down by 50% in Grand Rapids, Michigan over the next 15 years. So pretty effective public health intervention. It was 1950 when the United States Public Health Service endorsed fluoridation. Remember when we used to have a public health service?

Emily: [00:22:46] I still have it. It's just.

Perry: [00:22:47] And 1955, when the first fluoride toothpaste was introduced to the market, do you know what brand got their first crest? Crest. Crest. Toothpaste. By 1975, [00:23:00] fluoride toothpaste was sort of everywhere. The. The more interesting history is probably recent. So in 2024, a federal court found, quote, unreasonable risk of fluoridation under the Toxic Substances Control Act and ordered EPA Action. That ruling was subsequently vacated by a higher court. But in the interim, both Florida and Utah enacted statewide fluoridation bans in 2025. And so what you see over the past century and plus is a burgeoning understanding of the protective power of fluoride, a broad public scale adoption, and a much more recent backlash and sort of reducing of fluoride.

Emily: [00:23:48] Yeah. And I think in the current moment, it's kind of hard to overstate how much anxiety people have about this and how much you hear about this on certain [00:24:00] corners of the internet. You know, it's it does have the flavor of, you know, they're adding the water to fluoride, to the water to poison us. And also just the general flavor of like, this is something to be very worried about. Like your children may be damaged by this fluoridated water in some very meaningful way. And people are afraid. And that is then what drives some of these court decisions.

Perry: [00:24:24] It absolutely is. What drives I mean, I don't no one's saying like, we love cavities. This is this is all about neurodevelopment and IQ.

Emily: [00:24:32] And, you know, it's a place where you can put photos that totally freak people out. So like fluoride is added to your municipal water by adding small amounts of, I don't know, like it's a mineral. So like, yeah, rock crushed up rock, mineral fluoride rocks. They come and they come in bags and you can't just like eat bags of fluoride, you know, they're dangerous. It's a dangerous toxic chemical at high doses. And so those bags have, you know, skull and crossbones on them or whatever is marked for poison. And people [00:25:00] are like, look at this. They're adding poison to your water. It's like, well.

Perry: [00:25:04] Like, yeah, so does the.

Emily: [00:25:05] Potassium.

Perry: [00:25:05] Permanganate and the chlorine.

Emily: [00:25:07] Yeah, exactly. Like don't, don't eat that right out of the bag.

Perry: [00:25:11] Uh.

Emily: [00:25:12] Yeah. Nerd gummy cluster.

Perry: [00:25:14] That is a disingenuous argument. But, um, you know, I think it's.

Emily: [00:25:17] A very, very compelling one.

Perry: [00:25:19] Very compelling. Yeah. The dose makes the poison as as the toxicologist will tell you. And we're going to get to the IQ studies. Like I think it's important that we actually go through them with a little more depth. And here's a picture of a big bag of fluoride with a skull and crossbones on it.

Emily: [00:25:33] But first, because we love science so much, I think I always want to leave people out of these with an understanding of how science is cool. And if you understand the science, you can appreciate why you would do something. So fluoride helps your teeth by improving the enamel. Basically.

Perry: [00:25:53] It's really fascinating. So enamel, which is the protective covering on your teeth, has a crystal in it, [00:26:00] a crystal structure called hydroxyapatite. And fluoride integrates into the hydroxyapatite crystal just through regular chemistry. That makes it fluoroapatite when the fluoride is integrated there, and Fluoroapatite is a little denser than hydroxyapatite. It's less soluble, but the critical part is that enamel can dissolve at a low pH. Anyone ever dissolve a tooth in Coke for science fair project? Yep.

Emily: [00:26:30] So no. But I totally could, because my son apparently is saving all of his teeth in a small container that I found the other day. Because he's away at sleepaway camp. There's just, like a little container in his bathroom of all of his baby teeth.

Perry: [00:26:40] He's saving his teeth.

Emily: [00:26:41] Yeah, I don't, I, yeah, I don't even know where, like I thought I was supposed to take them, but we moved away from the tooth fairy when he figured out it wasn't real. I just Venmo him. Uh, and so I guess he's keeping the teeth, I don't know.

Perry: [00:26:51] I love it. Do you do you use the fairy emoji though on Venmo?

Emily: [00:26:56] I just, I just sometimes I leave him a note that's like I added some money to your.

Perry: [00:26:59] Oh [00:27:00] my God. Uh, so, um, yeah, so enamel.

Emily: [00:27:04] We got off topic.

Perry: [00:27:05] Enamel dissolves at a low pH and bacteria in your mouth release acid. And after you eat and the bacteria sort of growing and stuff like that. The pH gets around to five in your mouth. Now hydroxyapatite will start to dissolve around 5.5 pH, but fluoroapatite doesn't start to dissolve until a pH of about 4.5. So that's one pH unit. That's actually a ten fold difference in acid concentration because it's a log scale. So it makes it much more resistant to acid. There's also some thought that there's some antibacterial properties of fluoride as well. But bottom line this is well described. We know how this works. So the question is no longer like does fluoride truly protect teeth. Like we know it does. The question and I think the question more people have now is, [00:28:00] okay, I believe you that in 1945, maybe it was important to add fluoride to the water because that was the only way people were getting fluoride and etc. but now we have crest and other and other forms of toothpaste. And so, you know, do we still need to be fluoridating the water supply?

Emily: [00:28:18] Yeah. I think this is, I think, genuinely an interesting question because, of course, an intervention like dumping fluoride into the water supply is in some very, very effective, but in some ways a somewhat coarse intervention. And over time, you could imagine saying, well, everybody's got fluoride in their toothpaste now. And so we don't need to be using this other mechanism. And if if there's no purpose in this, then we shouldn't be doing it. Which of course is, is generally true. For me, this is an interesting, skeptical, skeptical case. It's probably the most interesting of the skeptical cases. You know, not so much is this harmful, but literally just is it is it doing anything? Is it necessary? Yeah. [00:29:00] And I think the honest answer here I go through some studies. I think the honest answer is there is not an airtight case as airtight a case now as there was in 1945. So we have some suggestive evidence. So, for example, uh, there's a paper in the Journal of Dental Research from 2018. It takes the Nhanes, which is a large nationally representative study that's used for many things. And it compares kids who live in counties with higher fluoridation versus lower. And the kids in the high fluoridation counties have, uh, fewer cavities, about 30% fewer cavities than the others. The issue is that these counties are really very different. They tend to be different in sort of how rural versus urban they are in their income and all kinds of other things that are also potentially driving cavities.

Perry: [00:29:54] And hey, flag that thought because it's going to come back when we talk about IQ differences and things [00:30:00] like that.

Emily: [00:30:01] This entire literature on both sides is, is rife with residual confounding. Our favorite.

Perry: [00:30:05] Topic. One of the things that the sort of anti-fluoride groups talk about a lot is the Cochrane Review on water fluoridation. So Cochrane, for those of you who don't know, is really the gold standard of the meta analysis world. They're a very rigorous group that puts together meta analyses. So combining multiple studies into one overall analysis to make big important statements about all sorts of health care stuff. And there is a Cochrane review on fluoridation that gets cited a lot, where they say that there is no evidence that the fluoridation of water supply after 1975 had a meaningful effect on cavities. So 1975 is the sort of arbitrary ish marker in time when like, okay, now there's fluoride toothpaste everywhere. Like everyone has access to fluoride toothpaste if they want it. So people trot out and like, okay, there it [00:31:00] goes. After 1975, there's no effect. So we're done. However, it's really no data. No.

Emily: [00:31:06] There's almost no data after 1970.

Perry: [00:31:08] Almost no data. The Cochrane Review focuses on the initiation of fluoridation in a water supply, and the truth is that very few places both initiated fluoridation after 1975. Most had already done it and also studied it and published it in in a in a paper form that Cochrane could use. And so there were only two studies that actually met their criteria for a post 1975 fluoride initiation. The confidence intervals around the effect size are incredibly wide. So this is one of those like we just like the evidence just isn't there one way or another as opposed to it doesn't really work. And you don't get that nuance when people talk about it on Instagram.

Emily: [00:31:47] Yeah. I mean, just to be clear, the, you know, we have randomized trials of toothpaste and tooth varnishes and things on your teeth for fluoride. So that that is very it's very clear that that reduces cavities. This is really a, [00:32:00] a sort of more epidemiological question and a big piece of the problem with these with these studies is that when everybody has fluoride in the water, then there is no introduction of them. And then you can't you can't evaluate. But what you can do a little bit. And where I think the evidence is potentially more helpful for the value of fluoridation of your water is the places that stopped doing this.

Perry: [00:32:25] Yeah. Like like Florida and Utah are about to be. Yeah.

Emily: [00:32:27] Like Florida and Utah are are about to. And so I think that you can imagine, you know, on the beginning side, we have this very good evidence from what happened when you first introduced fluoride to the water from zero. Now everybody has it. So the only way you're really going to figure out if it works from this point is if you turn it off.

Perry: [00:32:47] Yeah.

Emily: [00:32:48] And there are some places that have done that. So, uh, Calgary stopped fluoridating their water in 2011 and they saw compared to Edmonton, these are places in Canada, [00:33:00] apparently.

Perry: [00:33:00] Very nice places.

Emily: [00:33:03] I love you, Canada. They saw their cavities increase not enormously, but somewhat. And we see sort of similar things in some places in Alaska and in Israel. So Israel banned community fluoridation in 2014, and they actually saw about a doubling of child dental visits afterwards based on a time trend analysis. And so again, time trends, you know, people can always quibble, but I feel this is much stronger evidence than, say, comparing kids with fluoride versus non-fluoridated areas.

Perry: [00:33:37] And it also answers the public policy question better, which is, you know, if people are talking about if your municipality is debating whether or not to stop fluoridation, well, we have evidence of what happens when you stop fluoridation. And broadly, the rate of cavities goes up even in the modern era. There's one other thing before we move on from this. Does toothpaste [00:34:00] do the job well enough that I want to talk about that I think maybe doesn't get brought up enough, which is that there are substantial disparities in dental care in the United States in particular. Um, you know, insurance coverage for dental procedures is poor even at the best of times. And for many people, they essentially have no dental coverage. I think we take it for granted sometimes that everyone has access to fluoride toothpaste and has a home environment that is encouraging of and has the ability to get people to brush teeth frequently. And, you know, parents are around to get make sure their kids can brush their teeth before they go to bed, as opposed to being off at work and leaving kids with a sitter and all these kind of things. And so I, you know, I think that if fluoridation stopped in my area, my kids would be fine because they have their fluoride toothpaste and they go to the dentist every six months and they get cleanings [00:35:00] and they can get their fluoride varnishes. And even if they have a cavity, we'll pick it up quickly and it'll get filled quickly and everything will be fine and they'll probably be fine. And that's just not the case for all kids. And one of the I'm going back to my sort of concern about this pushback against public health is that hyper individualism, when it comes to health care decisions, tends to leave people behind that don't have the same privileges that other people do.

Emily: [00:35:25] Totally. I mean, I think, yeah, I was, I was my brain was in the same place on the thinking about vaccines that, you know, when we limit the access to basic public health interventions, the people who lose are disproportionately people who are have fewer other resources to make up for those losses. And this is very, very clear place where there is a huge, huge relationship between your socioeconomic status, your parental education, your parental income, and aspects of your dental health. Yeah. Where fluoride can fill in, when [00:36:00] some other things are not there.

Perry: [00:36:02] Absolutely. A safety safety net fluoride basically.

Emily: [00:36:04] Safety net fluoride.

Perry: [00:36:05] You know, I just said, oh hey, I can deal with a cavity if I get to be fair, my kids are not psyched about having a cavity at the dentist, getting, you know, Novocain and getting a tooth drilled. But I have certainly heard people say, look, cavities are fine. We can deal with that. There's no it's not that bad, essentially. Um, and Emily, we have some data, you know, it's probably obviously we're not randomizing kids to cavity versus no cavity, but there are some adverse downstream effects of dental health.

Emily: [00:36:36] There are some correlations between. Okay.

Perry: [00:36:38] Talk to me about correlations.

Emily: [00:36:39] Yeah. There are some correlations between dental problems and poor academic performance and school absenteeism. I mean, these are these are correlations. They aren't causal. I think the strongest arguments in favor of, you know, better fluoride, better dental care are that it improves people's teeth and experience of, you know, being [00:37:00] in the world with their teeth. And there's actually some long term sort of illness, things that relate to bacteria in your teeth. So, you know, it definitely. There's definitely a strong correlation with academic performance. I've read that as a reflection of who has access to dental care rather than a reflection of, you know, your cavities directly impacting your test scores.

Perry: [00:37:20] Fair enough. That's really the benefit of fluoride.

Emily: [00:37:25] Fluoride is good for your teeth. It's really good for your teeth. It's good for your teeth.

Perry: [00:37:29] I don't think that's what people want to talk about. Nope.

Emily: [00:37:33] No. People want to talk about the brain. Yeah. They want to talk about the concern. And this is the core issue here is the concern that fluoride exposure, especially during pregnancy and in early childhood, is associated with lower IQ. That is the that is.

Perry: [00:37:54] What.

Emily: [00:37:54] You're going to hear thing that people are talking about. That's what people hear. And that is where we want [00:38:00] to spend some time and give a fair hearing to, uh, after the break.

Perry: [00:38:11] All right. We're back talking about fluoridation and IQ, and there are a lot of studies out there. There are a lot of problems with studies on both sides of this issue. But I think to give all the data a fair hearing, it's worth talking about the studies that get sort of trotted out the most often so that we can dig into them a little bit. And I want to start with the quote unquote, Harvard study. You'll hear this referred to as the Harvard study. This is a study that appeared in Environmental Health Perspectives in 2012. And just.

Perry: [00:38:44] A little bit of an aside, a little bit of inside baseball here, just because an author works at Harvard doesn't make it a Harvard study. Like when I publish a study, it's not the Yale study. It's like it's my own work. Okay, so this is not like an official.

Emily: [00:38:59] What would [00:39:00] what would make it the Harvard study?

Perry: [00:39:01] I mean, I feel like if Harvard commissioned a study and they, you know, but no, this is just a lab at Harvard and study. It's just a study.

Emily: [00:39:11] Yeah.

Perry: [00:39:11] Okay. And as a as a Yale guy, I just take issue with it. And a former Harvard guy. All right. The Harvard study is a meta analysis of 27 studies looking at fluoride exposure and IQ in children. And the big the big take home that people will say about this study is that kids with a high exposure to fluoride had a roughly seven point lower IQ than kids with a lower exposure to fluoride. So we've got similar to what we talked about before, you know, looking at places in the world and differences in IQ. A correlation, not causation. But hey, it's the Harvard study. Fluoride reduces IQ. Emily, tell me a bit [00:40:00] more about the issues of the Harvard study.

Emily: [00:40:02] So I think the important thing to understand about this study is where most of these, the studies they make up, the meta analysis come from and what the water levels looked like. So, you know, we're talking we talk about fluoridation in the US. We're talking about 0.7 parts, parts per million. And that's kind of where people are aiming this meta analysis mostly combining studies that are run in parts of rural China that actually have very high levels of groundwater fluoride. So this is not places where they're adding fluoride to the water. It is places where the underlying rock is full of fluoride. Actually, the underlying rock is also often in these cases also full of arsenic and lead. These are places with some iodine deficiency. There's other kind of mineral deficiencies.

Perry: [00:40:50] Which often go together, by the way, like.

Emily: [00:40:51] Which often go.

Perry: [00:40:52] Together. Yeah. Groundwater, fluoride and groundwater, arsenic and groundwater lead are correlated, particularly because of industrial runoff.

Emily: [00:40:59] But [00:41:00] the fluoride levels in this water are very high. And so when they're estimating these these impacts, they're effectively saying, you know, how many IQ points? What's the effect on IQ of increasing fluoride from an already high level to an even higher level? And that is not really necessarily the relevant question for what would happen if we have small amounts of fluoride. And like with many things, and this is the core underlying point, like with many things, the dose makes the poison and very high levels of fluoride could be dangerous or could be problematic for development, while lower levels might not be. And this study is really largely focused on these higher levels, even putting aside the arsenic lead correlations.

Perry: [00:41:47] Very well said. These ecological studies. The broad term here is an ecological study where you're looking at an area, really a geographic area. You have an estimate of fluoride exposure in the area. You have an estimate of IQ [00:42:00] in the area. And that's you're correlating those two things. It's lower quality evidence. But we do have some, I think slightly higher quality evidence. There are studies that try to measure fluoride exposure more directly, often with urinary fluoride. And so I want to talk to you about this study that appeared in Jama Pediatrics in 2019. This is one of the more recent studies that used urinary fluoride. It was called the murex study 601 mother child pairs across, uh, six Canadian cities. And what they found was that a additional 1mg/l of fluoride was associated with a 4.5 lower IQ points in boys, although no Association in girls. It's a little hard to understand why there would be an effect in one group and not another. Emily, how do you how do you interpret the Mirecc study?

Emily: [00:42:58] I find the [00:43:00] patterns in this study pretty problematic for reasons that this is a kind of study where I read it and I can see like 50 different problems. And it's not just one problem. You sometimes you look at a study, you're like, oh, here's the one issue this study has has many issues. So the exposures here are mostly low. There are a few very high exposure areas that kind of seem to drive all the results. Uh, the estimates are very, very sensitive to adjustments for other family differences, which suggests that there's other stuff going on. There's really no reason to think that any kinds of effects here would appear in boys and Not for girls. So that's just like, feels a bit like what we'd call p hacking, just trying a bunch of different subgroups.

Perry: [00:43:41] Or cherry picking.

Emily: [00:43:42] Cherry picking your, your results. And it's a very small paper. You know, it's a few hundred subjects. I don't find this to be a very compelling paper for a lot of reasons.

Perry: [00:43:52] But it does get it gets brought out.

Emily: [00:43:54] A lot of traction.

Perry: [00:43:55] Um, so a couple of things. First, urinary fluoride [00:44:00] because I'm a kidney doctor.

Emily: [00:44:02] It's about urine, guys. Buckle up. Perry's got feelings about the kidneys.

Perry: [00:44:06] Just fast forward ten minutes if you want to skip this part. Um, no, it's not going to take that long. No, urinary fluoride is actually not, in my opinion, the best measure of fluoride exposure. When you measure anything in the urine, you have to account for urinary concentration. So the the concentration of urine can vary from roughly 100 milliosmoles per liter to 1000 milliosmoles per liter. So that's a factor of ten just based on, you know, like how concentrated your urine is. Many of these studies will adjust for some other proxy of urine concentration, like specific gravity. I'll just tell you as a nephrologist, specific gravity is not a great concentration marker in the urine. Some use osmolarity, which is a little bit better, but at least they think about this. Fine, but no one ever thinks about is urinary pH. So urine fluoride excretion is pH dependent. How acidic your urine is. Okay. And [00:45:00] the way it works is that in a acidic urine, 95% of the filtered fluoride is reabsorbed before it gets into the pee that comes out of your body. Okay, so so if you're acidic, you're absorbing a ton of fluoride in alkaline urine. Only 45% is reabsorbed, which is a dramatic difference. And so that means that the pH of your urine can really drive any finding in urinary fluoride that you want. And I've literally never seen a paper that adjusts for urinary pH. I don't know if the researchers are aware of it, but okay, guys, FYI, you've got to adjust for urinary pH. And a lot of things affect urinary pH, including diet, right? Like when you last ate and what kind of food. And if you have more vegetables or meats or all kinds of things that could be salient here. So. Okay. Everyone can come back now. I'm done talking about pee.

Emily: [00:45:56] I think what's okay, so what's interesting about this, uh, [00:46:00] and I like very much, I don't ever think about urinary pH. That's totally right. I've never literally never even heard of it until right now. But I think what, what this illustrates that I think is useful in many of these studies is they can seem by saying, we measured the, the we measured the fluoride in the urine. It seems better. Right? Like it seems a lot better than saying, you know, we looked at it, estimated.

Perry: [00:46:24] It based.

Emily: [00:46:25] On estimates. It's like, oh, it's a by it's like when people do brain scans, it's like, oh, you looked at the brain like, it's so fancy. It's like a fancy metric. But actually all of those metrics in this particular case have some of the same problems that any measure would have. You know, it's correlated with diet. It's correlated with other characteristics. So just because something seems like a more sciency measure doesn't actually mean it's a it's a better measure or a more accurate measure or less subject to bias. Thank you for coming to Perry's Ted talk about urine. So I think this literature, you [00:47:00] can sort of tell from some of this discussion is actually a bit confusing to people because we're saying, okay, there's this one study, but things are kind of big and there's another study, but we don't like urine. And also I have some vague complaints. For me, there is one kind of very nice paper that helps me organize this, which is a meta analysis from 2023, which took many of these studies of water fluoride and just did this kind of quite simple thing, but separated the studies into two groups. One was studies that were in high fluoride areas. So these are areas where the underlying level is high. And then they estimate what happens when you increase from there.

Perry: [00:47:48] And like India and Chinas of the world where there's just a lot of fluoride around. Yeah.

Emily: [00:47:52] And then also sort of separately looked at the set of studies that were comparing, they were looking at the impacts of fluoride from a low level. [00:48:00] Much many of these in Canada and Mexico. And what happens in the in the data you see this is that the, the high areas, it looks like when you add more fluoride, it's bad for IQ in particular for development because you're already at this high level. But at these low levels, at lower levels, the variation does not seem to relate to IQ, which is exactly what you would expect if this is bad for you at very high doses, but not at lower doses.

Perry: [00:48:32] Once again, the dose makes the poison. How are we doing in the US? Like what percent of our of our fluoride is high?

Emily: [00:48:43] Yeah, it's very, very low. So the CDC had a report in the kind of 2016 to 2021 period. And they looked at what share of the time was the water level above 2mg/l. And that is that is pretty high. And so you would want to bring it, [00:49:00] bring it down. But they found that happen in 0.01% of the cases that they looked at. And just to be clear, even in those cases, it's not that the water is always at this too high a level. These waters get fixed when they are too high. That's part of why you monitor a municipal water system. So it's really unlikely that people in the US are being consistently exposed to fluoride at levels that are consistently too high. Actually, if anything, the CDC found sort of systematic errors in the other direction.

Perry: [00:49:31] Too low based on targeting. Yeah. Um, a lot of the studies that show these effects are cross-sectional. So they're measuring, you know, urinary fluoride and IQ at the same time, or maybe just once over, you know, at at a certain age. I just wanted to call attention to the Broadbent study, which appeared in the American Journal of Public Health. Just a really elegant piece of epidemiology, which you often don't see where they followed everyone born [00:50:00] in Dunedin, New Zealand, between April 1972 and March 1973, every single person who was born that year got enrolled in this study in this town, which is so cool. And they followed them for 38 years longitudinally, like a big part of their lives. And they were measuring prospectively fluoride exposure and they had repeated IQ testing. And in that broadband study, there were no differences in IQ based on fluoride exposure. So repeated high quality measurements over time. Again there you can find studies on both sides of this issue. But I just wanted to make sure there's some balance that. Like it's not like every study, even though they're bad, finds a finding.

Emily: [00:50:39] Yeah. I mean, I think just, you know, my big, like general takeaway from this is it is true that high fluoride in water, like endemically high fluoride seems to have some negative impacts on IQ. The levels that we have in American tap water do not seem to have those effects. And quoting the first one doesn't make the second [00:51:00] one true.

Perry: [00:51:01] I certainly agree. And but I will say I'm not even sure that the high fluoride levels affect IQ. I honestly I don't have a great mechanism for that. Like I don't know why that would be. And secondly, there's just so much confounding when you know, you're living next to an industrial run off site. So your groundwater fluoride levels is spiking. Yeah.

Emily: [00:51:22] Very fair point.

Perry: [00:51:23] I also let's talk about kids IQ because this is how this always gets framed. And Emily, this is firmly in your Wheelhouse is the only. If we really care about IQ in our children. Is. Is fluoride the only lever we have to pull or like. Have there been other studies? Ideally, randomized studies that would suggest that we can move the needle on IQ in kids. Broadly speaking.

Emily: [00:51:48] There are many, many studies that suggest that we can move the IQ, the move the needle on children's IQ and children's development. They range from, you know, in low resource environments, [00:52:00] some very basic stuff like micronutrient supplementation, uh, like improved iodine, like let's talk about other metals that we enjoy. Uh, you know, iodine supplementation can be, uh, can be helpful if people are truly, are truly deficient. And then all kinds of evidence on early childhood education, better preschool access, head start, you know, support for parents. Like there's so much in that we could be doing overall to improve IQ that would have potentially much larger impacts than not giving people fluoride, which is like a crazy.

Perry: [00:52:40] Yeah. The only difference is that stopping fluoridation costs nothing. At least it doesn't cost the government anything it might cost us in terms of public health. Whereas all of these other interventions, you know, you have to have an item in the budget, right? But but this is high quality data. We have randomized controlled data that suggests, you know, [00:53:00] nutritional supplementation for kids at high risk will improve IQ in the long term.

Emily: [00:53:05] We have look, we have randomized data that reading to kids improves their IQ. You know, that's like, that is a well documented fact. And you know who helps with that? Dolly Parton. Do you know that Dolly Parton has a program where every kid get in Tennessee gets she has like a whole thing where you can get, like, free books.

Perry: [00:53:23] Yeah.

Emily: [00:53:24] By Dolly Parton. Like Dolly Parton is doing more for kids IQ, like by a billion margins than any even potential fluoride thing. It's like, why aren't we more focused on Dolly Parton?

Perry: [00:53:35] I think anyone can get a free book from Dolly Parton. Not just.

Emily: [00:53:38] Anyone. You can get a free book from her and you can read it to your kids. And that would be amazing because she's the best.

Perry: [00:53:43] She's the best. Thank you.

Speaker 10: [00:53:45] So great. Every month, it's like the greatest thing.

Emily: [00:53:47] Okay, this is now a Dolly Parton fan podcast.

Perry: [00:53:51] Um.

Emily: [00:53:51] There we go.

Perry: [00:53:52] Let's just touch on the little bit wackier stuff that I've seen from the influencers, which is that fluoride [00:54:00] will calcify your pineal gland, which is actually the third eye, which gives you your psychic powers. And really the reason for fluoridation is that it's to tamp down our psychic abilities. Now, I will admit that I have no psychic abilities. And so maybe that's why I have.

Emily: [00:54:17] You know, some, I have some. But that's, you know, it's because my my tooth hygiene is kind of limited. How how would one show that psychic abilities which are made up are affected by fluoride.

Perry: [00:54:30] Oh, Emily. Boy, did I look. I was like, there's got to be some way.

Emily: [00:54:34] It's gotta.

Perry: [00:54:35] Be something. There's got to be some wackadoo journal that. And I literally, I couldn't find anything on psychic abilities. I did find. Yes. Your pineal gland, I should say. The pineal gland secretes melatonin, which is the like sleepy chemical. That's that's good. And it does calcify as you get older, it is a part of the brain that is particularly prone to this. About 60% of people based on autopsy studies, will have a calcified pineal gland, and it can contribute to sleep difficulties [00:55:00] in people in their later life. There is no evidence that fluoride accelerates this process. It's just other aging stuff that does it. However, the crystal that forms in your pineal gland is hydroxyapatite.

Emily: [00:55:16] Same thing from the tooth enamel.

Perry: [00:55:17] That is, and fluoride binds to hydroxyapatite. So if you test it, you'll find fluoride there. But it's the same reason that you find fluoride wherever hydroxyapatite is. It's not affecting your psychic ability. Obviously, everyone knows that psychic ability lives in the suprachiasmatic nucleus.

Emily: [00:55:36] What is that a reference? I can't even I'm not even going to get into from.

Perry: [00:55:39] The sleep episode that that is.

Emily: [00:55:41] The.

Perry: [00:55:41] Central control of.

Emily: [00:55:42] Thought. That was. I thought we were like, back to Star Trek.

Perry: [00:55:45] Oh, no. What is psychic ability in Star Trek?

Emily: [00:55:47] Okay.Moving on.

Perry: [00:55:48] Okay, I want to put this all together in a way. Like I want to give respect to the people that study the impact of fluoride on kids. And I don't want to dismiss [00:56:00] it. I think there's a tendency in science circles to be like, that study was bad or had a flaw or wasn't perfect or wasn't how I would do it. And therefore I can disregard it totally. And I don't think that's fair. The way we need to interpret science is based both on the effect that is posited, right? The estimate of impact of the thing and the quality of the research. And I think the problem that people have here is that when the effect posited is bad or concerning or makes you uncomfortable, like affecting the brain of a developing child, right? There's a real ick factor there that we tend to ignore, that we should interpret that in the context of the quality of research. Like we're willing to accept a worse study with a bigger effect or a worse seeming effect than we would a better designed study with no effect or a not [00:57:00] gross or icky effect. And I think that's a problem. And I bet there's an economics term for it, but I'm not sure what it is.

Emily: [00:57:08] Not exactly. I mean, I think it is a problem and it encompasses a bunch of issues that people have with with cognition. I think one of them is just the idea of, of sort of salience. So once you tell people, you know, there's a like this might affect your kid's brain. Like it's kind of living in there and I can't sort of take it out. It just makes that fear very salient and, and real to me. And then hard to subject to a basic like, you know, rational risk benefit calculation. I also think this is a place where it's difficult to see either the risks or, or benefits for real. Like, you know, let's say something did lower your kid's IQ by one point. You would never know. Like that's not a meaningful.

Perry: [00:57:52] Yeah, this is something you can only, even if it's really, you can only detect across thousands of kids, not one kid. Yeah.

Emily: [00:57:59] And, and also [00:58:00] like your kid's going to get some cavities and you're not going to know whether it's because fluoride or not. So this we're all kind of arguing in a sort of diffuse, ambiguous space. And that gives a lot of value to just like, I don't know, stuff that lives in like, what is, what is living in your head more aggressively at the moment? And fear is more salient than And reassurance.

Perry: [00:58:20] That's. Yes. Yeah. This is this is driven by fear. It doesn't mean that there's nothing to worry about. But we do have to acknowledge that the studies are generally of poor quality. And you shouldn't live your life based on fear of poor quality studies. And you should be happy that our kids are not dying of cholera and dysentery, which is a real possibility for kids all around the world. Just to bring it back to the other stuff we add to water.

Emily: [00:58:48] All right. Perry. Fluoride in the water. Smash or pass.

Perry: [00:58:52] I am a smash. I think the fluoride benefits people with the least access, which is generally what I'm for from a public [00:59:00] health standpoint. And I think you should also read to your children. Emily, smash or pass.

Emily: [00:59:06] I'm a smash on fluoride, and I hope that we keep it in our municipal water supply. That's what I would like.

Perry: [00:59:15] All right, Florida, we'll see what happens. That's it for fluoride. Your mailbag. Question of the week after the break.

Mailbag: [00:59:26] Hi, Emily and Perry. This is Natasha from Massachusetts. My question came from your episode last week on gluten sensitivity, and it's about MSG. A lot of older people in my life, especially ones I go to Chinese restaurants with, are convinced that MSG is responsible for headaches, brain fog, everything that's wrong in the world. I've even heard it called Chinese restaurant syndrome. Is this actually a real thing? Msg tastes so good. It would be such a bummer to cut it out if you don't have to. Thanks so much.

Perry: [00:59:59] Emily. [01:00:00] Do you have MSG powder in your house?

Emily: [01:00:05] No, I do not. Do you use it next to your to your like mac and cheese cheese that you use on everything.

Perry: [01:00:13] I have a lot of powders. It's in my spice rack. I'm a big fan of MSG. So before we answer the question of whether you can be allergic to MSG, I have to say the science here is fascinating. Um, MSG monosodium glutamate is a chemical that binds to certain receptors on your tongue. Uh, they're called T1, R1, and T1, R3, which are the specific umami taste receptors. So this umami flavor, which is, um, that's sort of like meaty, robust, uh, type of flavor comes from food that has glutamate in it. Um, it's an unctuous flavor. Absolutely. And whenever you taste something umami, like, [01:01:00] whether it's like mushrooms or things like that, it is the glutamate. It's not from monosodium glutamate, but it is glutamate binding to those receptors that gives you that flavor. So, so we all kind of like that flavor, truffles, like that kind of stuff. That's all glutamate, monosodium glutamate. It's just a sodium attached to the glutamate and sodium is salt, you know?

Emily: [01:01:17] And so it's just like a salty umami delicious.

Perry: [01:01:19] It's just it's.

Emily: [01:01:20] Just.

Perry: [01:01:21] As much as like sucrose is the sweet and citric acid is kind of a prototypical, you know, sour, uh, monosodium glutamate is umami. Um, and it's, it's quite delicious. But Emily, you tell me, can you be allergic? Or maybe I should say sensitive?

Emily: [01:01:40] There's really no evidence that people can be sensitive to, to this. Um, and, and, you know, in fact, it would be surprising given that you also have sodium and you also have glutamate as you have outlined. And so the idea that like, together they would cause something that would be different from, from separate is not, doesn't have a lot of mechanistic view. I [01:02:00] think people just like eat too much from the restaurant and then they feel tired.

Perry: [01:02:05] Uh, yes, 100%. This is a classic example of, you know, MSG being being used in cooking. And there's a lot of other stuff that gets used in cooking. Um, you know, Chinese restaurants do Asian cooking in general does add MSG sometimes as a spice, much like I do sometimes just like adding salt or adding sugar or adding citric acid or whatever. But it is in all the other foods you eat too, that have that bit of, of flavor profile. And yeah, you just really can't be allergic to it. But there's a lot of salt and other stuff in that type of cooking, which can make you a little feel dehydrated and gross. And it's also really delicious. So you get full and sleepy and tired. Definitely.

Emily: [01:02:48] Yeah, it would be a mistake. Don't blame the MSG, but just drink some extra water. All right. That's it for us today. Stick with us next week when we'll ask what's the deal with ticks? [01:03:00]

Perry: [01:03:01] The bugs, not the Tourette's syndrome.

Emily: [01:03:04] Thing with bugs ticks the bug. Wellness, Actually is produced in association with iHeartMedia. Our senior producer is Tamar Avishai, our executive producer at iHeart is Jennifer Bassett. Our theme music is by Eric Deutsch, and our content is for educational purposes only.

Perry: [01:03:22] 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 wellness. Actually, pod. And don't forget, we want to hear from you. Head over to wellness.fm and leave us a question for our mailbag or suggest a topic for a future show.

Emily: [01:03:43] We'll let the influencers have the last word.

Influencer: [01:03:46] I'm going to expose some things about fluoride. Why have we been told we have fluoride in the drinking water to prevent tooth decay? You were told that too. Right? So was I.