AMA #15: Fluoride Benefits/Risks & Vagus Nerve Stimulation

ANDREW HUBERMAN: Welcome to the Huberman Lab podcast,

where we discuss science and science-based tools

for everyday life.

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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.

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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?

OK, 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'd 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, OK?

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.

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.

OK, why is fluoride in some drinking water at all?

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.

OK, your teeth are always in one state or the other,

or 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--

that's why it's called remineralization--

and get this.

This 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 "appetite" in it

because 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 ultrastrong, meaning

supraphysiologically 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.

OK, 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, OK, given the potential for fluoride to make

supraphysiologically 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.

It was, 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 supraphysiologically 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, 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 toothpastes.

OK, 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.

OK, now, the second half of the question

was, how much is the fluoride in drinking water harming us?

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.

That's not debated.

Again, there might be some dentists

that say, oh, 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"--

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.

OK, 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 0.7mg/l 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,

OK, if you're drinking half a gallon of tap water a day

versus a gallon versus just a couple of cups,

whether or not you are in that safe zone.

And of course, this is going to vary by body weight.

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.

If you think about this, everything's

by body weight volume.

And this is why drug dosages are most typically calculated

as a function of pounds or kilograms of body weight.

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.

It 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 a neurotoxicity, a.k.a.

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 concern,

kind of keeping an eye on this stuff-- you know, OK,

fluoride doesn't sound great for me,

but as long as the concentrations aren't too high,

some people will say, I've been drinking tap water my whole

life and I feel great, my teeth are strong, and my brain works,

and my thyroid seems fine--

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 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.

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 Mateina 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 an element electrolyte pack in or just

drink 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, 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 removes 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 will 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 nonfluoride-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 come in 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?

Because 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.

I think 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--

oh, 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 conditioned

response to hate cartoons, which I suppose did not work,

because I liked cartoons then.

I don't watch them now.

Truly, I don't watch them now.

So I sit down on 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 have been about five or six years old.

So I decide, in my infinite wisdom,

to just swallow all the fluoride paste.

So I start sucking 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, OK, I'm just going to do this.

And I'm going to sit there.

I'm basically 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 did you do to him?

She was very protective of me.

Thanks, Mom.

What did you do to him?

And then I said 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 confess, during the pandemic, it was probably less,

as they were 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, if you take that approach

and 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 build up,

but you can really cause some tenting of the gum

tissue above the teeth and those little recesses back in there

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 blasé about it.

Yeah, I 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

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You can sign up for the Premium channel by going

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Again, that's hubermanlab.com/premium.

And as always, thank you for your interest in science.

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