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Comment by paddw | Hacker News Reader

So we know that there is definitely little benefit from ingesting fluoride, and also that we can not rule out negative effects from ingesting fluoride. This seems like... a bit of a big deal?

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It's been known for awhile, but you'd get labelled as a conspiracy theorist for any mention of it.

It goes all the way back to Dr. Strangelove at least. There's a whole bit in there about it.

This organisation was big on that conspiracy (??) theory:

https://en.wikipedia.org/wiki/John_Birch_Society

An article about their role in the original referendum on fluoridation in Wichita:

https://www.kansas.com/news/article1101667.html

And a Fresh Air interview with a historian who recently wrote a book about the John Birch Society:

https://www.npr.org/programs/fresh-air/2023/05/17/1176658584...

The harmful dose is many orders of magnitude higher than the concentration in tap water.

Dose makes the poison. Literally any chemical in sufficient dose is poisonous

Tooth decay is caused by acid produced by bacteria.

It's too bad we can't displace the bacteria themselves instead of working downstream from that.

There are oral probiotics available, which aim to do just this. I'm not sure if any clinical trials have investigated their efficacy, however.

Except that we can! The oral microbiome can be modulated to get exactly what you’re asking: remove pathogens that are good at creating acid and replacing them with ones that are good at remineralizing.

Shameless plug for my company (Bristle Health) that is trying to do exactly that via oral microbiome testing and personalized recommendations and products to improve.

Interesting, can you tell more? I’ve tried oral probiotics without much effect.

Did notice a difference for a couple of days after taking antibiotics for a week for something else, but it quickly subsided (my regular micro biome probably quickly recolonised the mouth).

I searched for the name and found it, seems like they ship you a test kit, then ID the microbes in your mouth and make recommendations based on that.

I noticed L. ruteri in some screenshots which I already know from other probiotic uses.

You guys have anything on the market yet?

Indeed we do! We have an oral microbiome test you can find here: https://www.bristlehealth.com/pages/products

and our first probiotic here: https://www.bristlehealth.com/pages/probiotic

All the species in the probiotic have been clinically studied with evidence that supports improvement in the oral microbiome and reduction of oral disease. Although, for transparency, the mechanism of action of some of the probiotics is still unclear, and we're working on figuring that out to improve oral probiotics and products in the future.

Is there a reason we don't just rinse with a base?

Actually, the article says the report says harm happens at 2x the current recommended fluoridation level.

> But the report did find a possible link to cognitive harm at approximately two times the current

Keyword possible.

Also a long history of spurious statistical correlations where you find "possible" links.

e.g. for a while there was a scare for RF from overhead powerlines causing brain cancer.

Turns out, the issue is the statistics used to try and isolate an effect from a general population sample have bias: plug in any effect, and any grouping factor, and you'll probably observe a doubling of the risk.

This effect was the cause of a whole spate of "X may cause cancer" reports in the 2000s.

There are lots of "big deals" in the environment that we silently tolerate -- things which studies conclusively and repeatedly show are substantially detrimental:

* Roadside air pollution

* Lead pipes

* Indoor CO2 buildup

Studies relating to flouride are nowhere near as conclusive and show nowhere near the same magnitude of effect. If flouride is contributing negatively in a similar way, it's doing so to such a small extent that it very nearly falls within the margin of error. Anyone genuinely worried about flouride should consider double-checking that they've already taken more meaningful action regarding their health, such as going on a walk, getting a full night's rest, or opening a window.

Not from ingestion, but exposing the enamel periodically during the day to fluoride and having trace amounts of it on your saliva supports remineralisation.

I would think it's pretty much impossible to have it in your mouth and not ingest any of it.

Sure, but to achieve equal remineralization, you'll likely end up ingesting orders of magnitude more fluoride when delivered via drinking water vs toothpaste.

I think The Netherlands took it out of their potable/tap water some while ago (like in the '70s).

Because they added it to salt and toothpaste instead.

Fluoride in salt? I know they put iodine in table salt, but not fluoride.

In Germany you can definitely buy table salt with Fluoride in a supermarket.

It's available online, and stores in many countries carry it.

https://www.google.com/search?q=fluoridated+salt&tbm=shop

Toothpaste, for the most part, isn't swallowed. Salt, you can get any kind you want. I think this gives consumers more discretion/control over what they want to or do not want to ingest.

Yes, I agree. I was just pushing back against the common false narrative that no fluoride in tap water equals no fluoride at all. It's brought up as a fact in every online discussion about fluoride.

Usually it's alongside that one study that shows naturally occurring fluoride in water is harmful to children's mental development. Which is true, but neglects to mention that the areas studied (in rural China) had levels of fluoride twenty times higher then public water fluoridation programs and that the same study also included a control group at "normal" added fluoride level and found no negative effect.

Heres the study. You'll start to recognize it if you get involved in a few of these discussions.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1852689/

As an aside, your gums and tongue will absorb a lot - think about chewing tobacco, people putting cocaine on their gums, pills you leave under your tongue. This is also why resorts will tell you to brush your teeth with bottled water.

While it obviously absorbs less than eating any compound, it still absorbs quite a bit!

I can tell you that salt is not fluoridated in the Netherlands (most people who care about cooking use pure sea salt anyway). As for toothpaste, almost every toothpaste anywhere in the world has it.

There is evidence both ways, the original reports were that children's dental health improved after they stopped fluoridation in the 70s.

> There is evidence both ways, the original reports were that children's dental health improved after they stopped fluoridation in the 70s.

Has that effect been persistent? I would think the news of flouride being removed from the water would cause an increase in dental health diligence, but I would also be surprised if that effect didn’t wane over time.

I remember growing up in the 80s in the Netherlands I used to get daily fluoride tablets, from a small pink bottle. Did not persist long I believe, but was definitely common back then.

I don't know what they do in the Netherlands, but in rural parts of the United States where people are on well water, fluoride treatments are common. Florida is directly applied to the teeth during a dental visit, then washed out.

Anecdotally, this is what I had and I have great Dental Health despite for brushing hygiene. I often skip brushing my teeth and almost never floss and haven't had a cavity in 40 years

Fwiw, I’ve pretty much always lived with access to municipal water with added flouride and have also always been given flouride treatment at the dentist. I think the latter is pretty universal in the US.

We don’t fluoridate our water but from 12-18 we do “fluor happen” (loosely translated: “fluor biting”), where we are given an upper and a lower bit which are both filled with heavily fluoridated gel, you bite into it and after a couple of minutes you take the bits out, rinse your mouth and then spit out any left-overs.

That’s interesting. Hadn’t heard of that. How common is this practice?

It’s very common in the US as well. It’s called fluoride treatment and is usually reserved for children.

In Italy, many years ago, when I was a kid, this fluoride bite was something that was given to us at (elementary) school, cannot remember if once or twice a year, they made a sort of quick medical checkup and while the doctor was visiting you, you had this bite.

But the practice was later abandoned, as it seems that the 6-8 age is the worst one to supplement (too much) fluoride, that could later develop in dental fluorosis:

https://en.wikipedia.org/wiki/Dental_fluorosis

I forgot about this. This was a total nightmare for me as a kid. The gel made me want to throw up badly. I think they offered two "flavours" you could pick from, both equally nightmarish.

I grew up in the US and remember this too, an absolute gag inducing gel that they put in a little mouthguard shaped thing and jammed in your mouth.

There have been various iterations of dentist office flouride treatments I remember.

As an adult the dentists I went to switched to a 2x 30 second rinse (60 second?) with a mouthwash at the end of the appoinment.

The last 10 years they eliminated that and I do a nightly flouride rinse.

I lived various places as a kid, from 10-18 I lived somewhere with no flouride in the water (rural with well water) and we did pills and dentist treatments instead.

Too much in this thread assumes everything is the same everywhere in a given country.

I have also probably never brushed my teeth with a non fluoride toothpaste living in the US. So it's not like that's different from the EU.

I have very little tooth decay in my mid 40s.

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