5 ms·

Major Flaws in 2025 Meta-Analysis on Fluoride and Children IQ Scores

103 points by jandrewrogers 2y ago

casenmgreen 2y ago
Site blocks Tor.
- jandrese 2y ago
  Here is the abstract if you can't load the page normally: A recent meta-analysis in this journal (Taylor et al 2025) produced ostensible evidence of a negative correlation between fluoride exposure and intelligence in children, which garnered major public attention. There has, however, been criticism of this undertaking and conclusions. In order to address the controversy over this work, we in this special communication undertake an independent forensic meta-science review of the methodology and statistical approaches employed and inferences drawn by the authors, as well as an investigation of the underlying data integrity of the constituent studies. We find that the authors employed unjustified methodological and statistical errors which invalidate their conclusion, and demonstrate that the data cannot be analysed as the authors assert. We further find major problems with the sources employed, including reliance on studies from non-MEDLINE indexed publications with an anti-fluoridation editorial stance, and major underlying issues with the data reported in several instances, indicative of impossible or unreliable data. Taylor et al is not reliable nor are its errors remediable. It should be retracted to avoid harms to public health and scientific discourse.
  - sevensor 2y ago
    > Taylor et al is not reliable nor are its errors remediable. It should be retracted to avoid harms to public health and scientific discourse It’s a bit late for that! “Fluoride makes you dumb” is now established in the public discourse as if it were true.
JumpCrisscross 2y ago
Honestly, as long as we’re not collectivising the cost of dental caries, and insurers can discriminate dental pricing based on fluoridation if they choose to, I’m okay with folks who don’t brush their teeth doing whatever they want to.
- jeffbee 2y ago
  That's just not how a society should work. Children should get a fair chance at life no matter how ignorant or negligent their parents are. Fluoridated water keeps teeth in mouths and students behind desks instead of missing school.
  - amluto 2y ago
    This is also true for measles and chickenpox, both of which have quite unpleasant or even lethal medium-to-long-term consequences in some fraction of people who appear to have recovered.
  - JumpCrisscross 2y ago
    > Children should get a fair chance at life no matter how ignorant or negligent their parents are I agree in principle. But this just isn’t the country we live in. Smart states and communities can still think this through logically. But it may be for the best to let the antivax rural areas do their own thing and stick to themselves.
    - themaninthedark 2y ago
      >antivax rural areas I would be careful with what size brush you are painting. >There are, of course, the familiar anti-vaxxers, who spoke up as early as February with concerns about a mandatory vaccine. There are also new groups. One is connected to far-right extremism and conspiracy theories (about the virus and otherwise). The other, termed “vaccine-hesitant,” is more surprising. It includes members of the opposite demographic — highly educated, liberal, not libertarian >While a majority of those unwilling to get a vaccine are Republicans, 42% of Democrats agree with them https://harvardpolitics.com/the-new-anti-vax/ https://harvardpolitics.com/the-new-anti-vax/
      - roguecoder 2y ago
        The anti-vaxx movement was really strong among ex-hippies when I was growing up. It's all the same people who believe in homeopathy and chiropractors. Part of the problem is presenting it as a choice makes people think it is legitimate to choose "no". I believe the consequence of not vaccinating should be social exclusion until you catch up: anything else is stochastically depraved heart murder.
delichon 2y ago
If in order to avoid a healthcare treatment, you have to avoid drinking or bathing or cooking with the public water supply, and also avoid most restaurant food, do you still have the right of informed consent to that treatment?
- wobblyasp 2y ago
  So do you avoid going outside to reduce exposure to environmental pollutants? Water fluoridation is a net-benefit to society.
  - delichon 2y ago
    I don't think informed consent is violated by removing a pollutant. But adding a substance as a healthcare treatment denies informed consent as an individual right, and turns it into a majority right. I'd hate for that to happen to other civil rights.
    - doug_life 2y ago
      Should we also stop adding iodide to salt or fortifying white bread? I see your point, but society has benefited as a whole by forcing some of these substances onto populations. I think it's fairly evident that many humans in the US are either unable or unwilling to really care about their health.
      - barbazoo 2y ago
        It's also extreme individualism we've all been indoctrinated with and which is turned up to 11 in the US.
      - perrygeo 2y ago
        Bad analogy. Fortified food provide nutrients to supplement what you get from other foods. One can simply choose to buy white bread that's fortified, or whole foods that have those nutrients naturally. You can't avoid water for too long though. Ingesting whatever is in the water supply is mandatory. I can't avoid flouride in my water any more than I can avoid Nitrogen when I breathe. I have no choice in the matter. It's the lack of choice that many object to, not the health effects of flouride per se. Personally, if given the choice, I'd probably still take flouride. Having it in the water is convenient. Mandatory, but convenient.
pieter_mj 2y ago
Fluor is an electron stealer. Enough for me not to touch it with a ten foot pole. Besides, tooth regrowing/regeneration will be available in the next few years.
- sva_ 2y ago
  As well as the cure for cancer
- neogodless 2y ago
  > Fluoride, as an ion (F-), is not reactive in the same way that elemental fluorine (F2) is. Fluoride ions are stable and typically do not readily gain or lose electrons, while elemental fluorine is highly reactive due to its strong electronegativity and tendency to attract electrons from other elements.
- hwillis 2y ago
  bad news about salt, then.
  - meepmorp 2y ago
    maybe they just don't want to deal with all the electronegativity
roguecoder 2y ago
It is not that expensive to run double-blind fluoride experiments. There are hundreds that have been run over decades. There is a Scotland that the found an 81.4% reduction in cavities. A double-blind study from New Zealand found no benefit to osteoporosis is postmenopausal women. Etc. Etc. If these neurocognitive effects were actually measurable, they wouldn't need to cherry-picking population-level correlation studies to find effects that are within the margin of error of the tests.
- choffee 2y ago
  "Hi we would like to give your child something that we think will lower their intelligence would you sign here please."
  - roguecoder 2y ago
    Even if you believed that to be the case, you could choose an area that had high natural fluoride in the water, provide gravity filters and then double-blind supplement fluoride at a moderate level for one group. It is certainly more ethical than saying "we are definitely going to let your children's teeth rot because some people think, on the basis of circumstantial evidence, it might have approximately the same effects as not having children's books in the home."
  - JumpCrisscross 2y ago
    > we would like to give your child something that we think will lower their intelligence “The association between drinking carbonated drinks, eating chips and intelligence level was significant (P= 0.043, 0.001) and prevalence odds ratio of 1.5 and 2.4 respectively” [1]. Anyone arguing this is about childhood IQ and wouldn’t similarly ban (not stop mandating, ban) soft drinks, chips and fast food for kids, they’re signalling this is about something other than kids’ health. (Note: this isn’t my mole hill. I think communities should have the right to make this call on their own. And the cited study quality is just as good as the fluoride causes autism ones.) [1] https://pmc.ncbi.nlm.nih.gov/articles/PMC3507933/ https://pmc.ncbi.nlm.nih.gov/articles/PMC3507933/
jmward01 2y ago
Is there a solid 'trust this paper' site out there? I would think that something could be built that rated papers on how much they have been reproduced, supported or refuted by other papers.
- uncertainrhymes 2y ago
  The Cochrane Library (https://www.cochranelibrary.com/ https://www.cochranelibrary.com/) generally has good meta-analysis on various topics. I often prefer that to any one paper.
sys32768 2y ago
I live in a town where most people grew up on well water, but we grew up in cities in another state with fluoridated water. When I took my daughter to see a dentist here, the dentist saw my daughter's good teeth during the check-up and said, "You didn't grow up here, did you?"
- JumpCrisscross 2y ago
  N = 1 doesn’t work for these effect sizes. Each of brushing frequency, use of proper toothpaste, flossing, diet, hydration and I think even genetics affect dental health more than fluoride. The point is fluoride in water provides a good catch-all if those practices aren’t followed.
  - const_cast 2y ago
    The studies on fluoride in drinking water indicate HUGE reductions in cavities. I don't think it's a catch-all, it's just effective.
midtake 2y ago
It is still a medical treatment added to the water supply, and sets a dangerous precedent. This same power if unchecked has the potential for great harm. As for efficacy, the same (or greater) benefits to enamel hardness can be obtained from using fluoride toothpaste anyway, I do not see the urgency for this. They've stopped fluoridating their water in Scandinavia for years now.
- ajross 2y ago
  > It is still a medical treatment added to the water supply, and sets a dangerous precedent. This same power if unchecked has the potential for great harm. Fluoridation started in US water supplies 80 (eighty) years ago. The people who set that "dangerous precendent" are all dead now. Seems like we've done OK with that "unchecked potential for great harm". I mean, come on. Even as a libertarian argument this seems tone deaf in a month where we're literally rolling back the fourth amendment.
- erickf1 2y ago
  Very good point!
- itishappy 2y ago
  > They've stopped fluoridating their water in Scandinavia for years now. Note that Scandinavia has naturally high fluorine levels in their groundwater: > In Sweden, fluoride concentrations in drinking water from water treatment plants have been reported to mostly range between 0 and 1.5 mg/L, with a maximum level of 4.1 mg/L, while in private wells in South-Eastern Sweden, it was found that 24% out of about 4,800 wells exceed 1.5 mg/L. In Norway, a study from 2017 found that 4 of 201 waterworks had fluoride concentrations exceeding guideline value of 1.5 mg F/L. In a study from Western Norway, the fluoride concentration in selected wells ranged from 0.51 to 8.0 mg F/L, and drinking water was the only dietary variable associated with increased risk of dental fluorosis. In Denmark, analyses of drinking water show most sources being low and below 1.5 mg F/L. https://pmc.ncbi.nlm.nih.gov/articles/PMC10770722/ https://pmc.ncbi.nlm.nih.gov/articles/PMC10770722/ The US targets 0.7 mg/L. Many European countries also choose to add fluorine to milk and/or salt instead of water.
- 2y ago
AStonesThrow 2y ago
Look, folks, you're being lied to, and you're victims of pseudoscience, and it's easy to prove using facts and logic, so downvote away at your own peril. Heavy industry, the dental industry, and your municipalities are lying to you when they say that drinking fluoride helps your teeth. Now when a dentist applies a fluoride treatment in a paste or appliqué, the solution stays in contact with living bone for a significant dosage time. The process is known as "remineralization" and so there is scientific basis for such a treatment to be effective. But when you drink water with the same substance, it quickly washes around those bones and into your esophagus. It doesn't stick around. It's like getting a cross tattoo to become Jesus. Fluoride will be digested, and absorbed into your bloodstream, and cross your blood-brain barrier, for sure! But it won't stay adhering to your tooth-bones and the remineralization process never has a chance to start. That's absurd thinking that it somehow is internally effective. It's simply not the mechanism of action. There's not enough time for it to work. The process requires physical contact in order for a chemical reaction to occur! Fluoride is, however, well-known to produce favorable psychoactive effects. For the past century or more. That's why we got Prozac, where the active ingredient is "fluoxetine". Prozac was the next step forward in getting fluoride to the masses who may not drink black/green tea, or live in fluoridated municipalities. I have a meta-hypothesis that excess surplus of any product is often remarketed as beneficial. For example, heavy industry produced massive amounts of talc and they were able to parlay it into many products as a powder. I simply feel the same way about minerals such as magnesium. How much Epsom salt is sold, simply because industries need to unload this stuff by the 5lb bag, vs. how good it works in a bathtub, I don't really know. But I literally envision cigar-filled back rooms where executives go "we can profit by digging a lot of this crap out of the ground and putting it on store shelves, or just dumping it right into water supplies, if only there's a way to convince everyone it's good for them!" And there's nothing different with the way lithium's being used, either. It used to be a soft-drink additive! Wait until they begin lithiating all your potable water supplies! (Sort of horrific, because side effects of lithium consumption include polydipsia and polyuria...!) But fluoride is the biggest scam of the 20th century. It's pseudoscience and quackery that sold it to the general public, and your cities are literally lying through their teeth when they don't tell you their ulterior motive and they pretend that there is "evidence" of beneficial effects on teeth. Nothing could be further from the truth. Y'all might as well believe in phrenology and astrology.
amai 2y ago
Water fluoridation is considered very common in the United States, Canada, Ireland, Chile and Australia where over 50% of the population drinks fluoridated water. Most European countries including Italy, France, Finland, Germany, Sweden, Netherlands, Scotland, Austria, Poland, Hungary and Switzerland do not fluoridate water. https://en.m.wikipedia.org/wiki/Water_fluoridation_by_country https://en.m.wikipedia.org/wiki/Water_fluoridation_by_countr... Make your own conclusions.

103 points by jandrewrogers 2y ago

casenmgreen 2y ago

Site blocks Tor.

jandrese 2y ago
Here is the abstract if you can't load the page normally: A recent meta-analysis in this journal (Taylor et al 2025) produced ostensible evidence of a negative correlation between fluoride exposure and intelligence in children, which garnered major public attention. There has, however, been criticism of this undertaking and conclusions. In order to address the controversy over this work, we in this special communication undertake an independent forensic meta-science review of the methodology and statistical approaches employed and inferences drawn by the authors, as well as an investigation of the underlying data integrity of the constituent studies. We find that the authors employed unjustified methodological and statistical errors which invalidate their conclusion, and demonstrate that the data cannot be analysed as the authors assert. We further find major problems with the sources employed, including reliance on studies from non-MEDLINE indexed publications with an anti-fluoridation editorial stance, and major underlying issues with the data reported in several instances, indicative of impossible or unreliable data. Taylor et al is not reliable nor are its errors remediable. It should be retracted to avoid harms to public health and scientific discourse.
- sevensor 2y ago
  > Taylor et al is not reliable nor are its errors remediable. It should be retracted to avoid harms to public health and scientific discourse It’s a bit late for that! “Fluoride makes you dumb” is now established in the public discourse as if it were true.

JumpCrisscross 2y ago

Honestly, as long as we’re not collectivising the cost of dental caries, and insurers can discriminate dental pricing based on fluoridation if they choose to, I’m okay with folks who don’t brush their teeth doing whatever they want to.

jeffbee 2y ago
That's just not how a society should work. Children should get a fair chance at life no matter how ignorant or negligent their parents are. Fluoridated water keeps teeth in mouths and students behind desks instead of missing school.
- amluto 2y ago
  This is also true for measles and chickenpox, both of which have quite unpleasant or even lethal medium-to-long-term consequences in some fraction of people who appear to have recovered.
- JumpCrisscross 2y ago
  > Children should get a fair chance at life no matter how ignorant or negligent their parents are I agree in principle. But this just isn’t the country we live in. Smart states and communities can still think this through logically. But it may be for the best to let the antivax rural areas do their own thing and stick to themselves.
  - themaninthedark 2y ago
    >antivax rural areas I would be careful with what size brush you are painting. >There are, of course, the familiar anti-vaxxers, who spoke up as early as February with concerns about a mandatory vaccine. There are also new groups. One is connected to far-right extremism and conspiracy theories (about the virus and otherwise). The other, termed “vaccine-hesitant,” is more surprising. It includes members of the opposite demographic — highly educated, liberal, not libertarian >While a majority of those unwilling to get a vaccine are Republicans, 42% of Democrats agree with them https://harvardpolitics.com/the-new-anti-vax/ https://harvardpolitics.com/the-new-anti-vax/
    - roguecoder 2y ago
      The anti-vaxx movement was really strong among ex-hippies when I was growing up. It's all the same people who believe in homeopathy and chiropractors. Part of the problem is presenting it as a choice makes people think it is legitimate to choose "no". I believe the consequence of not vaccinating should be social exclusion until you catch up: anything else is stochastically depraved heart murder.

delichon 2y ago

If in order to avoid a healthcare treatment, you have to avoid drinking or bathing or cooking with the public water supply, and also avoid most restaurant food, do you still have the right of informed consent to that treatment?

wobblyasp 2y ago
So do you avoid going outside to reduce exposure to environmental pollutants? Water fluoridation is a net-benefit to society.
- delichon 2y ago
  I don't think informed consent is violated by removing a pollutant. But adding a substance as a healthcare treatment denies informed consent as an individual right, and turns it into a majority right. I'd hate for that to happen to other civil rights.
  - doug_life 2y ago
    Should we also stop adding iodide to salt or fortifying white bread? I see your point, but society has benefited as a whole by forcing some of these substances onto populations. I think it's fairly evident that many humans in the US are either unable or unwilling to really care about their health.
    - barbazoo 2y ago
      It's also extreme individualism we've all been indoctrinated with and which is turned up to 11 in the US.
    - perrygeo 2y ago
      Bad analogy. Fortified food provide nutrients to supplement what you get from other foods. One can simply choose to buy white bread that's fortified, or whole foods that have those nutrients naturally. You can't avoid water for too long though. Ingesting whatever is in the water supply is mandatory. I can't avoid flouride in my water any more than I can avoid Nitrogen when I breathe. I have no choice in the matter. It's the lack of choice that many object to, not the health effects of flouride per se. Personally, if given the choice, I'd probably still take flouride. Having it in the water is convenient. Mandatory, but convenient.

pieter_mj 2y ago

Fluor is an electron stealer. Enough for me not to touch it with a ten foot pole. Besides, tooth regrowing/regeneration will be available in the next few years.

sva_ 2y ago
As well as the cure for cancer
neogodless 2y ago
> Fluoride, as an ion (F-), is not reactive in the same way that elemental fluorine (F2) is. Fluoride ions are stable and typically do not readily gain or lose electrons, while elemental fluorine is highly reactive due to its strong electronegativity and tendency to attract electrons from other elements.
hwillis 2y ago
bad news about salt, then.
- meepmorp 2y ago
  maybe they just don't want to deal with all the electronegativity

roguecoder 2y ago

It is not that expensive to run double-blind fluoride experiments. There are hundreds that have been run over decades. There is a Scotland that the found an 81.4% reduction in cavities. A double-blind study from New Zealand found no benefit to osteoporosis is postmenopausal women. Etc. Etc. If these neurocognitive effects were actually measurable, they wouldn't need to cherry-picking population-level correlation studies to find effects that are within the margin of error of the tests.

choffee 2y ago
"Hi we would like to give your child something that we think will lower their intelligence would you sign here please."
- roguecoder 2y ago
  Even if you believed that to be the case, you could choose an area that had high natural fluoride in the water, provide gravity filters and then double-blind supplement fluoride at a moderate level for one group. It is certainly more ethical than saying "we are definitely going to let your children's teeth rot because some people think, on the basis of circumstantial evidence, it might have approximately the same effects as not having children's books in the home."
- JumpCrisscross 2y ago
  > we would like to give your child something that we think will lower their intelligence “The association between drinking carbonated drinks, eating chips and intelligence level was significant (P= 0.043, 0.001) and prevalence odds ratio of 1.5 and 2.4 respectively” [1]. Anyone arguing this is about childhood IQ and wouldn’t similarly ban (not stop mandating, ban) soft drinks, chips and fast food for kids, they’re signalling this is about something other than kids’ health. (Note: this isn’t my mole hill. I think communities should have the right to make this call on their own. And the cited study quality is just as good as the fluoride causes autism ones.) [1] https://pmc.ncbi.nlm.nih.gov/articles/PMC3507933/ https://pmc.ncbi.nlm.nih.gov/articles/PMC3507933/

jmward01 2y ago

Is there a solid 'trust this paper' site out there? I would think that something could be built that rated papers on how much they have been reproduced, supported or refuted by other papers.

uncertainrhymes 2y ago
The Cochrane Library (https://www.cochranelibrary.com/ https://www.cochranelibrary.com/) generally has good meta-analysis on various topics. I often prefer that to any one paper.

sys32768 2y ago

I live in a town where most people grew up on well water, but we grew up in cities in another state with fluoridated water. When I took my daughter to see a dentist here, the dentist saw my daughter's good teeth during the check-up and said, "You didn't grow up here, did you?"

JumpCrisscross 2y ago
N = 1 doesn’t work for these effect sizes. Each of brushing frequency, use of proper toothpaste, flossing, diet, hydration and I think even genetics affect dental health more than fluoride. The point is fluoride in water provides a good catch-all if those practices aren’t followed.
- const_cast 2y ago
  The studies on fluoride in drinking water indicate HUGE reductions in cavities. I don't think it's a catch-all, it's just effective.

midtake 2y ago

It is still a medical treatment added to the water supply, and sets a dangerous precedent. This same power if unchecked has the potential for great harm. As for efficacy, the same (or greater) benefits to enamel hardness can be obtained from using fluoride toothpaste anyway, I do not see the urgency for this. They've stopped fluoridating their water in Scandinavia for years now.

ajross 2y ago
> It is still a medical treatment added to the water supply, and sets a dangerous precedent. This same power if unchecked has the potential for great harm. Fluoridation started in US water supplies 80 (eighty) years ago. The people who set that "dangerous precendent" are all dead now. Seems like we've done OK with that "unchecked potential for great harm". I mean, come on. Even as a libertarian argument this seems tone deaf in a month where we're literally rolling back the fourth amendment.
erickf1 2y ago
Very good point!
itishappy 2y ago
> They've stopped fluoridating their water in Scandinavia for years now. Note that Scandinavia has naturally high fluorine levels in their groundwater: > In Sweden, fluoride concentrations in drinking water from water treatment plants have been reported to mostly range between 0 and 1.5 mg/L, with a maximum level of 4.1 mg/L, while in private wells in South-Eastern Sweden, it was found that 24% out of about 4,800 wells exceed 1.5 mg/L. In Norway, a study from 2017 found that 4 of 201 waterworks had fluoride concentrations exceeding guideline value of 1.5 mg F/L. In a study from Western Norway, the fluoride concentration in selected wells ranged from 0.51 to 8.0 mg F/L, and drinking water was the only dietary variable associated with increased risk of dental fluorosis. In Denmark, analyses of drinking water show most sources being low and below 1.5 mg F/L. https://pmc.ncbi.nlm.nih.gov/articles/PMC10770722/ https://pmc.ncbi.nlm.nih.gov/articles/PMC10770722/ The US targets 0.7 mg/L. Many European countries also choose to add fluorine to milk and/or salt instead of water.
2y ago

AStonesThrow 2y ago

Look, folks, you're being lied to, and you're victims of pseudoscience, and it's easy to prove using facts and logic, so downvote away at your own peril. Heavy industry, the dental industry, and your municipalities are lying to you when they say that drinking fluoride helps your teeth. Now when a dentist applies a fluoride treatment in a paste or appliqué, the solution stays in contact with living bone for a significant dosage time. The process is known as "remineralization" and so there is scientific basis for such a treatment to be effective. But when you drink water with the same substance, it quickly washes around those bones and into your esophagus. It doesn't stick around. It's like getting a cross tattoo to become Jesus. Fluoride will be digested, and absorbed into your bloodstream, and cross your blood-brain barrier, for sure! But it won't stay adhering to your tooth-bones and the remineralization process never has a chance to start. That's absurd thinking that it somehow is internally effective. It's simply not the mechanism of action. There's not enough time for it to work. The process requires physical contact in order for a chemical reaction to occur! Fluoride is, however, well-known to produce favorable psychoactive effects. For the past century or more. That's why we got Prozac, where the active ingredient is "fluoxetine". Prozac was the next step forward in getting fluoride to the masses who may not drink black/green tea, or live in fluoridated municipalities. I have a meta-hypothesis that excess surplus of any product is often remarketed as beneficial. For example, heavy industry produced massive amounts of talc and they were able to parlay it into many products as a powder. I simply feel the same way about minerals such as magnesium. How much Epsom salt is sold, simply because industries need to unload this stuff by the 5lb bag, vs. how good it works in a bathtub, I don't really know. But I literally envision cigar-filled back rooms where executives go "we can profit by digging a lot of this crap out of the ground and putting it on store shelves, or just dumping it right into water supplies, if only there's a way to convince everyone it's good for them!" And there's nothing different with the way lithium's being used, either. It used to be a soft-drink additive! Wait until they begin lithiating all your potable water supplies! (Sort of horrific, because side effects of lithium consumption include polydipsia and polyuria...!) But fluoride is the biggest scam of the 20th century. It's pseudoscience and quackery that sold it to the general public, and your cities are literally lying through their teeth when they don't tell you their ulterior motive and they pretend that there is "evidence" of beneficial effects on teeth. Nothing could be further from the truth. Y'all might as well believe in phrenology and astrology.

amai 2y ago

Water fluoridation is considered very common in the United States, Canada, Ireland, Chile and Australia where over 50% of the population drinks fluoridated water. Most European countries including Italy, France, Finland, Germany, Sweden, Netherlands, Scotland, Austria, Poland, Hungary and Switzerland do not fluoridate water. https://en.m.wikipedia.org/wiki/Water_fluoridation_by_country https://en.m.wikipedia.org/wiki/Water_fluoridation_by_countr... Make your own conclusions.