- Welcome to the Huberman Lab Podcast, where we discuss science and science-based tools for everyday life. I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. Today is an Ask Me Anything episode or AMA. This is part of our premium subscriber channel. Our premium subscriber channel was started in order to provide support for the standard Huberman Lab Podcast, which comes out every Monday and is available at zero cost to everybody on all standard feeds, YouTube, Apple, Spotify, and elsewhere.

We also started the premium channel as a way to generate support for exciting research being done at Stanford and elsewhere, research on human beings that leads to important discoveries that assist mental health, physical health, and performance. I'm also pleased to inform you that for every dollar the Huberman Lab premium channel generates for research studies, the tiny foundation has agreed to match that amount.

So now we are able to double the total amount of funding given to studies of mental health, physical health, and human performance. If you'd like to subscribe to the Huberman Lab Podcast premium channel, please go to HubermanLab.com/premium. It is $10 a month to subscribe, or you can pay $100 all at once to get an entire 12 month subscription for a year.

We also have a lifetime subscription model that is a one-time payment. And again, you can find that option at HubermanLab.com/premium. For those of you that are already subscribers to the premium channel, please go to HubermanLab.com/premium and download the premium subscription feed. And for those of you that are not Huberman Lab Podcast premium subscribers, you can still hear the first 20 minutes of today's episode and determine whether or not becoming a premium subscriber is for you.

So without further ado, let's get to answering your questions. The first question is about fluoride. And the specific question is, why is fluoride in our water and how much is it harming us? Okay, well, that might seem like a short question, but there's actually a lot to that question.

And I want to be very clear by posing the question, how much is it harming us? It implies that fluoride is harming us. And I want to be very clear, the degree to which fluoride can harm you or not harm you depends on how much of it happens to be in the water or toothpaste or some other thing that you're consuming.

Okay, so this is very important. I don't want the question to seem like a leading question to imply that fluoride is necessarily harming us because as I'm about to tell you, there are clear benefits of fluoride for tooth strength and for warding off cavities. But if you get too much fluoride into your system, it is dangerous.

It is a poison at certain levels. So as you've probably heard before, the dose makes the poison. So let's take this seemingly simple question and dissect it in two. The first part of the question was, why is fluoride in our water? And believe it or not, even that is hard to answer directly because here's what's happening right now in 2024.

There is a major lawsuit in the state of California to try and get fluoride removed from the drinking water. The outcome of that case is still yet to be determined, but the case was filed by a group of individuals who strongly believe that fluoride at any concentration in the drinking water is bad.

Why would they say that and what is their evidence and how strong is that evidence? Well, there is some evidence that if levels of fluoride in drinking water exceed a certain threshold, it can cause problems with thyroid hormone function and perhaps even certain aspects of brain function. Again, if the levels exceed a certain threshold.

So in the state of California, there is a major lawsuit to try and get fluoride removed from the drinking water. Now at the same time, meaning right now, there is also a major lawsuit in the United States, this one taking place in Buffalo, New York, whereby citizens are suing the city because they insist that there is not enough fluoride in the water and they are suing for damages based on the dental health needs of their children that did not, in their opinion, get enough fluoride in the drinking water.

So I'm telling you about all of this because the question again was, why is fluoride in our drinking water? And believe it or not, there are certain states in the United States, certain areas of the United States where the fluoride levels in the drinking water are low, are zero, perhaps.

That's what the lawsuit in Buffalo is about. And by the way, the city of Buffalo may have now corrected the amount of fluoride in the water, taking it from zero to something. Whether or not it was actually zero is still debatable, but I think you're starting to get the point that there is a wide, wide divergence in terms of how safe people feel about having fluoride in drinking water.

Some people want it and are suing cities because they feel there wasn't enough of it in their drinking water, and others don't want any fluoride in their drinking water, and they're suing cities because of that, okay? So this is a really barbed wire topic, as I like to say.

It's one that no matter how close you get to it, whatever angle you look at it, you're likely to get stuck a little bit it's going to be a little bit painful. Okay, why is fluoride in some drinking water at all? Okay, let's set aside the levels and just answer that question.

Well, in an upcoming episode of the Huberman Lab podcast about oral health, I'll get into this in a lot more detail, but fluoride is a really interesting compound with respect to oral health, and here's why. Your teeth, believe it or not, are always in a state of either demineralization or remineralization.

Those are tricky words to say. Go ahead and try and say it. Demineralization, remineralization. So I'm going to refer to them as demin for demineralization and remin for remineralization. Okay, your teeth are always in one state or the other, where one state predominates versus the other. Now, a cavity in your mouth occurs when bacteria, in particular, Streptococcus mutans, sometimes called strep mutans, feeds on sugars in your mouth, and then as a byproduct of that feeding, creates acids that then erode the enamel and deeper layers of your teeth.

In other words, it demineralizes the tooth. Now, I just told you that your teeth can be in a state of demin or remin at any moment. The way that your teeth remin, the way they remineralize and can potentially fill in little cavities that have not yet made it to the deeper layers of your teeth is through a process that involves the construction of crystals from minerals.

Okay, that's why it's called remineralization. And get this, this is really wild. These minerals actually stack together in very organized little sequences, kind of like Lego blocks. And the critical element within those blocks is something called hydroxyapatite. I love that it has the word apatite in it 'cause we're talking about oral health.

That's the normal process. Fluoride was discovered not because it's a vitamin, not because it's an essential nutrient. In fact, at high concentrations, it's actually a poison. I'll tell you a story about that in a moment where I was actually poisoned by fluoride at the dentist when I was a kid, in large part due to my own error.

Fluoride, it was discovered, can actually get inside of those Lego chain-like crystals, the building of those, and form bonds between them that are actually stronger than the hydroxyapatite bonds that would normally form. In other words, if you consume fluoridated water or use toothpaste with fluoride, especially if you do this when you're a kid, what ends up happening is that the crystals and the mineralization structure of the teeth becomes ultra strong, meaning super physiologically strong, which then limits the ability for that strep mutans and the acid strep mutans produces when it eats sugar to erode the enamel of your teeth, causing what we refer to as cavities.

Okay, so I went and asked several dentists and a periodontist about why is fluoride in drinking water? Why is fluoride in toothpaste? And they, of course, gave me the explanation that I just gave you, which is a chemical mechanical explanation or rationale. However, most of the things for our health, such as the foods we eat, the amount of exercise that we do, are not naturally put into our environment, right?

But tap water, which goes out to everyone who consumes it from the tap, is basically a government or local government supplied resource. And basically the rationale was, and I believe this took place first in the 1950s, was, okay, given the potential for fluoride to make super physiologically strong teeth, what can we do to reduce the cavities and tooth decay that would occur in children and adult populations?

Let's put fluoride in the drinking water. So that's what they did. They did not do this, I was told, because it was necessarily the best way to take care of teeth and avoid cavities. It turns out there are a bunch of other things that you can do. Even if you consume no fluoridated water or toothpaste, there are things that you can do to enhance the mineralization state of your teeth, even fill in cavities, provided those cavities haven't made it into the deeper so-called dentine layers of the teeth.

I'll get into all of this in that future episode. But what the US and other governments decided, this of course varies across the world to the extent to which there's fluoride in the drinking water or not, was that by putting fluoride in the drinking water, they could prevent a large amount of tooth decay and cavities that would otherwise occur, okay?

It was a, and remains, a fairly low cost approach for these cities to introduce fluoride to the drinking water. And that's why fluoride is in drinking water. It is to try and create super physiologically strong teeth. And indeed, every single dentist I spoke to, including functional dentists, I spoke to periodontists, I spoke to several dentists ranging from, let's call them more traditionally trained dentists to more, let's call them alternative dentists, all of them agree that at a chemical, mechanical level, fluoride creates stronger teeth.

However, every single one of them also acknowledged that the bonds that are created in those mineralization chains, as I'm referring to, I realize that's not the technical term, is not the normal hydroxyapatite bonds that would form. They are stronger than the bonds that would normally form. They are structurally different.

If you look at them down what's called an electron microscope, you'll see that they're structurally different. And some, not all of the dentists I spoke to, said, yeah, you know, it would be best to remineralize the teeth to fill in any cavities that initially have formed, again, not down to the deep layers, but they could still be filled in naturally through the building up of those hydroxyapatite natural bonds.

But they acknowledged that many people, perhaps most people, don't take adequate care of their mouths and their teeth. So they understood the rationale of putting fluoride into drinking water. And of course, that's also why fluoride is in many, not all toothpaste. Okay, so I'm hoping that clearly answers for you the question of why there is fluoride in our drinking water at all.

At least in most American cities, there is fluoride in the drinking water. Although this lawsuit in Buffalo, I guess soon to be determined, will probably tell us whether or not indeed there was a total lack or a partial lack of fluoride in the drinking water there. I'm presuming that the accusation is true, but I don't actually know that to be true.

I just know that there's a lawsuit that exists. If you Google that, you can see some YouTube videos about it. There's information about this happening. There are a bunch of angry parents and I'm sure there are angry parents on the other side. And I don't know what the kids are saying, but hopefully no matter what, they're saying them through healthy teeth.

Okay, now the second half of the question was, how much is the fluoride in drinking water harming us? Okay, I'm going to answer this question very specifically. The person asks, how much is the fluoride in our drinking water harming us? Well, I already told you ways in which it is helping the strength of your teeth, right?

That's not debated. Okay, again, there might be some dentists that say, oh, you know, the bonds that are formed by fluoride are different than the ones that are naturally created with no fluoride. And so there might be some debate about that, but all of them acknowledge that those bonds and the mineralization of the teeth is stronger with fluoride.

They understand and agree with the rationale, even if they don't necessarily agree with the practice as the best practice. How much is fluoride in drinking water harming you? Well, there are two things you need to ask. One is how much fluoride are you actually drinking? Because it turns out there's a tremendous range of fluoride concentrations in tap water, depending on what city you live in.

Now, I did an entire episode of the Huberman Lab podcast about water. We talked about distilled water versus spring water. We talked about hydrogenated water. We talked about alkaline water. We talked about all of those things. And we did talk about fluoride. And one of the key takeaways when you're thinking about fluoride in drinking water is to know that if fluoride concentrations in drinking water are too high, or, and this is a very important or, or you're consuming a lot of a particular water that contains even low levels of fluoride, well, there's the potential.

And again, I want to highlight the word potential here. I don't want to cause alarm. That the fluoride is causing disruptions to thyroid hormone output or on the receptor end, in other words, disruptions to thyroid hormone metabolism and usage in the body. Okay, I want to be really clear here.

I don't want people to think, oh, fluoride destroys your thyroid hormone. It's the dose that makes the poison. It depends on how much. Now, the Center for Disease Control have set a recommended level of 0.7 milligrams per liter, 0.7 milligrams per liter of fluoride in drinking water as the level, and here I'm paraphrasing, that can help prevent tooth decay and promote good oral health and that they have deemed safe.

But if you want to know how much fluoride is in your drinking water, whether or not it is above, at, or below that value, you need to get your tap water tested. Now, fortunately, there are websites that can tell you how much fluoride is in your drinking water. And if you trust the data on those websites, you can simply put the city you live in into one of those websites and you'll get the information back.

I'll provide a few links to those different websites in the show note captions for this episode. We also provided those links in the show note captions for the episode on water. And then you can see, are you adjusting the level of fluoride in your drinking water that's deemed safe, less than that value, or more than that value?

But keep in mind that if you drink a little bit, a moderate amount, or a lot of fluoridated drinking water, you're going to be consuming either more or less fluoride. Just because there's a concentration that's been deemed safe by the Center for Disease Control does not actually tell you whether or not, okay, if you're drinking half a gallon of tap water a day versus a gallon versus just a couple cups, whether or not you are in that safe zone.

And of course, this is going to vary by body weight, right? If you're a small child, those lower levels of fluoride are going to equate to a larger total amount of fluoride as seen by the volume of the body, right? If you think about this, right? Everything's by body weight volume.

This is why drug dosages are most typically calculated as a function of pounds or kilograms of body weight, right? Not everybody gets the same dose of every drug. And if you're a very large person, maybe you can tolerate more fluoride. As I mentioned before, high levels of fluoride have been shown to disrupt thyroid metabolism.

It has also been hypothesized, again, this is still highly debated, hypothesized to be neurotoxic under certain conditions, that is toxic to neurons that can kill neurons at certain concentrations, not necessarily the concentrations present in your drinking water. A lot of the evidence that fluoride is neurotoxic is from so-called in vitro studies.

So studies done effectively in a dish, although there is some in vivo evidence that it can cause neurotoxicity, AKA neurodegeneration. So I think when it comes to the topic of fluoride, people tend to bin out into not concerned and simply want fluoride to strengthen their teeth. Mildly concerned, you know, kind of keeping an eye on this stuff.

You know, okay, fluoride doesn't sound great for me, but you know, as long as the concentrations aren't too high, you know, as people will say, I've been drinking tap water my whole life and I feel great, you know, my teeth are strong and my brain works and my thyroid seems fine.

Okay, and then people who are very, very concerned about fluoride at any concentration in their drinking water, hence the lawsuit in California and other lawsuits around the country. So I believe that when we're talking about fluoride, you really need to think about the dosages and you need to ask yourself which one of those three categories you fall into.

Now, if you are concerned about fluoride, it does not necessarily mean that you can't drink tap water. The suggestion simply would be to filter that tap water. And during the episode I did on water, I talked about a number of different filtration approaches. Many of those filters will filter out fluoride and you can simply look up, you know, water filters that eliminate or reduce fluoride.

And then some people have enough disposable income and/or are concerned enough about fluoride in their drinking water that they will purchase or create very extensive, very thorough filtration systems to completely eliminate fluoride from their drinking water. Okay, so you'll find different ranges of concern. Again, aside from the data of high fluoride levels being disruptive to thyroid hormone pathways and possibly neurotoxic, I personally am somebody who filters the drinking water I consume out of the tap.

Unless that is, I'm going to boil water with it for making things like loose leaf yerba mate, which is one of my favorite drinks. Although lately I drink this cold brew Matina yerba mate, which by the way is made with purified water, no fluoride, and so on and so forth.

But if I'm making rice or I'm making pasta or I'm making oatmeal and I need to use tap water, I don't worry about removing the fluoride from that water. However, if I'm going to drink water, if I'm going to mix, you know, an element electrolyte pack in or just drinks a glass of water or go out on a hike and take some water with me, I do use a water filter, either a filter that fills from the top and then seeps down and the ones you put in the refrigerator, or I recently purchased a whole house filter for the drinking water taps in my house so that it does remove all the fluoride and remove some other contaminants as well.

So it's going to depend on your level of concern and it's going to depend on your disposable income and any number of other things. And I must say that every once in a while, I'll drink a little bit of tap water out of the tap without any concern about filtering the fluoride.

I'm not somebody who gets hyper concerned about these things but I do understand why some people do get hyper concerned about these things, especially people who've read up on fluoride and some of the health concerns of consuming too much fluoride, because I also find it very logical and understandable that as people learn more about how a particular substance might be harming their brain or bodily health, that they would become more concerned about consuming that substance.

It just stands to reason. So what am I suggesting? I suggest that you figure out how much fluoride is in your tap water. I suggest that you then make a decision as to whether or not to filter that water or not before drinking it. And then of course, you have to make a decision about what sort of financial investment you're willing to make to filter that water.

You can find a list of different price ranges of water filters in the show note captions in the water episode. You may also want to watch that episode and go to that timestamp. And there's an enormous range there. I want to be very clear. I don't have a financial relationship to any of those filtration mechanisms.

Again, some people have $0 to devote to that process of taking the fluoride out of their water and other contaminants. Some people have many, many tens of thousands of dollars. So it really just depends on your disposable income and your level of concern. But if you were to ask me, I would say, yeah, I think, given that the cost of most of the filters that can remove most of the fluoride is low, and given that there is some health concern of consuming too much fluoride, why not just remove fluoride from the drinking water?

And then if you say, well, won't that weaken my teeth? Then I would say, well, watch the episode that's soon to come out on oral health, because it's going to explain a lot of approaches, including fluoride containing toothpaste, but some other non fluoride containing toothpaste and other things that one can do that the community of professionally trained dentists all agree can really help improve the mineralization state of your teeth.

And indeed can fill in cavities that have begun to form, but haven't yet made it to the deeper layers of your teeth and on and on. Now, I do have a brief story about fluoride that I'd be remiss if I didn't tell you, which essentially shows that fluoride is designed to strengthen teeth, but is also indeed a poison.

So when I was a kid, I had a lot of dental issues. I didn't consume much sugar. My mother fortunately was good about not letting us consume too much sugar, but for whatever reason, my mouth was kind of a mess. I'd brush, I'd floss, I would do all these things, but I actually had my adult teeth coming behind my baby teeth.

So it didn't push out my baby teeth. So not only did I not collect from the tooth fairy, which I only recently discovered isn't real, but how would I know? 'Cause the tooth fairy never showed up because all of my adult teeth came in behind my baby teeth. So I had to have all of my baby teeth pulled on the top.

So I did not have a good relationship to the dentist as a location or a person. In fact, they had to tell me not to bite the dentist. By the way, I haven't bitten a dentist in a long time. So hopefully my dentist, if watching this, is not too concerned.

I do get twice a year cleanings. Every dentist agrees that's a good thing to do. Some people may need less, some people may need more, but how do you know? You need to go to a dentist to find out. Back to the story about fluoride. I started going to the dentist quite a bit because of all these dental issues that I had as a kid.

And what they used to do, I don't know if they do this anymore, but what they used to do is they give you these little trays which are kind of like mouth guards that you would use for boxing or hockey so your teeth don't get knocked out. And they would fill those trays with this jelly-like stuff that contained fluoride.

And they put it on the top and on the bottom. And the stuff just, little bits of it would seep onto your tongue and your throat. And it was so sour, it was so awful. And they'd seat me in this little wicker chair in front of a television and turn on cartoons as if that was supposed to make me forget how awful the whole experience was.

If anything, it probably just created a Pavlovian condition response to hate cartoons, which I suppose did not work 'cause I liked cartoons then. I don't watch them now, truly, I don't watch them now. So I sit down in this wicker chair, I've got the fluoride in my teeth with these two trays, and I'm just hating this whole process.

I think I must've been about five or six years old. So I decide in my infinite wisdom to just swallow all the fluoride pace. So I start shucking it down through these mouth guards. I can feel it going back into my throat and it's sour and it's stinging, it's awful, but I'm thinking, okay, I'm just going to like, you know, do this and I'm going to sit there.

I'm basically going to, I'm going to beat the test. And so I drink all this fluoride paste. And then of course I got immensely sick within about three minutes. I stood up, I turned around and puked all over the wicker chair. I think that was deliberate. Actually looking back, it was deliberate.

And puke all over the wicker chair. My mom comes running in, what happened? What'd you do to him? You know, she was very protective of me, thanks mom. What'd you do to him? And then I said, you know, I just swallowed the stuff. They wanted to do it again.

And I stopped doing the fluoride treatment at that point. Why did I vomit? Well, I vomited because fluoride is indeed a poison at high concentrations. Now, do I tell you that story to make you afraid of giving your kids fluoridated toothpaste or fluoridated water? No, by all means, do what you think is best for you and for your children.

For me, however, I've made some effort to avoid fluoride toothpaste. I do go to the dentist, as I mentioned, about once a year. I confessed during the pandemic, it was probably less as they were, you know, busy and it was hard to schedule, et cetera. I've had very, very few cavities in my adult life, hardly any.

And my gum health is very strong, et cetera, et cetera, largely through taking on protocols that I'm going to describe in the oral health episode and that were recommended to me by friends who are both dentists and other friends who are periodontists because again, there are a lot of things that we can do to strengthen our teeth in natural ways by building up those hydroxyapatite bonds, which are the natural bonds that teeth form.

And yes, believe it or not, being able to reverse some early formed cavities as long as they haven't made it deep into the tooth. Also things like using a soft toothbrush, because if you brush too hard, you know, if you take that approach, you're going to brush your teeth really hard, get them really, really clean.

Yes, you'll scrape off all the biofilm, you'll avoid tartar buildup, but you can really cause some tenting of the gum tissue above the teeth. And those little recesses back in there are where bacteria get in. And there's now a lot of really strong evidence showing that some of that bacteria can translate into cardiac disease, can translate into metabolic disease, and maybe even into some neurologic disease.

So it's serious stuff. Oral health is one of the most important areas of health, and it's one of the most overlooked areas of oral health. And I think people generally fall into two categories, and I'll use these two categories to frame up the episode on oral health that's coming.

One category of person seems really bullish on their oral health. They're like, "Keep my teeth white and clean," and they floss and brush twice a day, every day, and they use tooth whiteners and mouthwash and all those things. And the other category is kind of blase about it. "Yeah, brush my teeth in the morning so that my breath doesn't kill every person I get into an interaction with," and so on and so forth.

But in reality, both the group of people that are doing an immense number of things to try and keep their teeth white and their breath fresh are, yes, doing things that are good for their oral health, but also no doubt damaging their oral health, in particular, the oral microbiome, which is absolutely critical.

And then, of course, the other category of people that are neglecting their oral hygiene and are not taking mouthwashes and things like that are also damaging their oral health, but in different ways. So during the episode on oral health, I'll spell out all the things that you can do, most of which, by the way, are completely zero cost.

Many of them actually will save you money, both in the short and long-term, and can really help you improve your oral microbiome, the strength of your teeth, and reduce the number of cavities, maybe even reverse cavities that have begun to form and are not too deep into the tooth yet.

And in a really nice way, all of that independent of your stance on fluoride. Thank you for joining for the beginning of this Ask Me Anything episode. To hear the full episode and to hear future episodes of these Ask Me Anything sessions, plus to receive transcripts of them and transcripts of the Huberman Lab podcast standard channel and premium tools not released anywhere else, please go to HubermanLab.com/premium.

Just to remind you why we launched the Huberman Lab podcast premium channel. It's really twofold. First of all, it's to raise support for the standard Huberman Lab podcast channel, which of course will still be continued to be released every Monday in full length. We are not going to change the format or anything about the standard Huberman Lab podcast.

And to fund research, in particular research done on human beings. So not animal models, but on human beings, which I think we all agree is a species that we are most interested in. And we are going to specifically fund research that is in toward developing further protocols for mental health, physical health, and performance.

And those protocols will be distributed through all channels, not just the premium channel, but through all channels, Huberman Lab podcast and other media channels. So the idea here is to give you information to your burning questions in depth and allow you the opportunity to support the kind of research that provides those kinds of answers in the first place.

Now, an especially exciting feature of the premium channel is that the tiny foundation has generously offered to do a dollar for dollar match on all funds raised for research through the premium channel. So this is a terrific way that they're going to amplify whatever funds come in through the premium channel to further support research for science and science related tools for mental health, physical health, and performance.

If you'd like to sign up for the Huberman Lab premium channel, again, there's a cost of $10 per month, or you can pay $100 upfront for the entire year. That will give you access to all the AMAs. You can ask questions and get answers to your questions, and you'll, of course, get answers to all the questions that other people ask as well.

There will also be some premium content, such as transcripts of the AMAs and various transcripts and protocols of Huberman Lab podcast episodes not found elsewhere. And again, you'll be supporting research for mental health, physical health, and performance. You can sign up for the premium channel by going to HubermanLab.com/premium.

Again, that's HubermanLab.com/premium. And as always, thank you for your interest in science. (upbeat music) (upbeat music)