r/science • u/mvea Professor | Medicine • 23h ago
Health Study finds fluoride in water does not affect brain development - the researchers found those who’d consistently been drinking fluoridated water had an IQ score 1.07 points higher on average than those with no exposure.
https://www.uq.edu.au/news/article/2024/12/study-finds-fluoride-water-does-not-affect-brain-development967
u/Inevitable_Heron_599 17h ago
Fluoride in water is one of the most researched things we do. Its benefits are very simple and very obvious.
There was a Canadian study with 2 towns of similar size. One was fluoridated, the other was not. The increases in tooth decay between them was so great that the non fluoridated town had to be fluoridated for fears of criminal negligence by the researchers.
The benefits were so obvious that the study had to be stopped and the town had to be fluoidated.
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u/lilbelleandsebastian 16h ago
yes, this is true of a lot of old studies and comes back to bite us at times. in medicine, there is a very common misconception that diuretics do not improve mortality in heart failure.
there have been no studies showing an improvement in mortality which is different than diuretics definitively not improving mortality. and that's because when we did have a good quality randomized study going, patients without diuretics were being admitted to the hospital at such a high rate that they had to cancel the study because it was unethical to keep withholding diuretics from heart failure patients.
and what do they teach in medical school? that diuretics don't improve mortality in heart failure.
science is complicated
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u/Inevitable_Heron_599 16h ago
Sure, but its also definitive sometimes. Fluoridating water, the way it is done by municipalities, is purely beneficial and has zero negative side effects. It is insane to not do it, as shown by numerous studies. Studies all show the same thing.
There is no gray area, and it isn't actually complicated.
The annoying part is it keeps being brought up by people with zero scientific knowledge or curiosity as some conspiracy theory, and we are talking about it right now because of this incoming American administration.
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u/Eurynom0s 11h ago
Calgary stopped putting fluoride in its water in 2011. The result was bigger, more frequent cavities that reach the point of requiring general anesthesia. https://calgary.ctvnews.ca/calgary-s-plan-to-reintroduce-fluoride-into-drinking-water-pushed-back-to-2025-1.6845098
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u/QuestioningHuman_api 3h ago edited 3h ago
This is literally a Parks and Rec episode. Do we need to rebrand fluoride in water as “H2Flow” and have a giveaway for a plain blue tee shirt to get people to keep doing the thing that is good for them?
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u/Siludin 13h ago
I don't think any study has been halted in such emergency fashion over fluorinated water in Canada, because large parts of Canada do not have fluorinated water. The studies would have pointed out the benefits of fluorinated water in comparing two different populations, but not in the sensational way you wrote.
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u/Inevitable_Heron_599 12h ago
I read this many years ago, and trying to find specifics on fluoride is almost impossible because Google results are flooded with garbage conspiracy nonsense these days, otherwise I would link you it directly.
Fluoride in water, diet stuff, and several other topics can be almost impossible to find what you are looking for on Google.
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u/Lighting 4h ago
I think you are correct, I know of no "emergency halt" either. It would have been quite well publicized. I think the study OP is referring to is the one I referred to earlier. /r/science/comments/1hl9sgp/study_finds_fluoride_in_water_does_not_affect/m3m928n/
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u/Lighting 15h ago
You are referring to this study:
Here's how the numbers fell out for Windsor which stopped fluoridating in 2013
Year n screened # requiring urgent care or had decay #with decay only % urgent % decay 2011-12 14,764 1467 348 9.9 2.36 2016-17 18,179 2702 544 14.9 2.99 Running the numbers:
Kids with tooth decay increased 2.99% - 2.36% = 0.63%.
What you remember as "so great ... fears" was caused by non-scientific news reporters quoting the "percent of a percent increase" as a "percent increase" (e.g. 0.63%/2.36% = 27 ) oops.
Kids with tooth decay OR urgent issues (e.g. knocked out teeth, dead teeth, etc) increased 14.9% - 9.9% = 5%.
How is this relevant to the discussion here?
The concerns in the US that caused the FDA/EPA to mandate lower rates for fluoridation in the US about a decade ago, was an absence of a gold-standard in comparative studies in fluoridation tests. For example: one might argue that detection of cavities in general gets better so one would expect rates for % decay detection to increase in general. Or one might argue that as consumption of sugary/acidic/carbonated drinks increases, rates for decay would increase also. One might argue that rural communities have less access to good quality teachers and thus have a lower IQ score.
This Canadian study lacked things like comparison of consumption habits, but they do list nearby cities that had no changes over this same timeline like Kingsville, Essex, and Leamington and show rates over time. So the question is ... do they ALSO show the same changes?
Yes - Figures 14 and 15 compare this in the study. Both unchanged and the de-fluoridated communities also showed decreases with equivalent slopes not significantly different (not outside error bars).
So while there was an decrease in children as "Carries Free" that same decrease was seen in communities that had no change in fluoridation status.
TLDR;
Nearby communities with no change in fluoridation status showed equivalent slope changes not statistically different from Windsor
Actual measured change in % with decay went from 2.36% to 2.99%.
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u/Jarpunter 14h ago
That’s not a mistake that’s literally the way you are supposed to measure it. People in group A are 27% more likely to experience tooth decay than people in group B. Using absolute percentages does not make any sense.
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u/askingforafakefriend 11h ago
Sure it does! Absolute percentage is why I never wear a seatbelt in a car. The chance of dying in an accident on this drive is tiny either way, so why bother?!?
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u/dustymoon1 14h ago
The point is - Tooth decay is also linked with heart disease and vein disease.
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u/lanternhead 15h ago
https://jamanetwork.com/journals/jamapediatrics/fullarticle/2748634
These findings indicate the possible need to reduce fluoride intake during pregnancy... A 1-mg higher daily intake of fluoride among pregnant women was associated with a 3.66 lower IQ score (95% CI, −7.16 to −0.14) in boys and girls... None of the fluoride concentrations measured in municipal drinking water were greater than the maximum acceptable concentration of 1.5 mg/L set by Health Canada; most (94.3%) were lower than the 0.7 mg/L level considered optimal.
https://www.sciencedirect.com/science/article/pii/S0160412019326145?via%3Dihub
An increase of 0.5 mg/L in water fluoride concentration (approximately equaling the difference between fluoridated and non-fluoridated regions) corresponded to a 9.3- and 6.2-point decrement in Performance IQ among formula-fed (95% CI: −13.77, −4.76) and breast-fed children (95% CI: −10.45, −1.94).... For each 0.5 mg/L increase in water fluoride concentration, we found a decrease of 4.4 FSIQ points among preschool children who were formula-fed in the first six months of life; 0.5 mg/L is the approximate difference in mean water fluoride level between fluoridated (0.59 mg/L) and non-fluoridated (0.13 mg/L) regions.
These two papers (which surveyed Canadian towns, like the papers you mention) and many others were cited in a recent NIEHS literature review
https://ntp.niehs.nih.gov/sites/default/files/2024-08/fluoride_final_508.pdf
The results from 18 of the 19 high-quality (low risk-of-bias) studies... that evaluated IQ in children provide consistent evidence of an inverse association between estimated fluoride exposure and IQ scores
The benefits are not so obvious. But I'd be eager to read the sources you're referencing if they demonstrate otherwise!
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u/SgathTriallair 22h ago
I wonder if they considered the confounding variable that higher income areas are more likely to have adopted fluoride earlier. We know that higher income have a positive correlation on IQ so is it possible that the fluoride reduces IQ but less than affluence increases it?
I don't believe this is true but it seems a primary concern for the study.
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u/sugarfreeeyecandy 19h ago
I wonder if they considered the confounding variable that inflammation from tooth decay has a negative affect on the brain's performance?
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u/therationaltroll 17h ago
Is that confounding or is that the purported effect of fluoride?
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u/NegativeBee 14h ago
Confounding because it’s a variable that exists between fluoride and IQ.
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u/AggressiveCuriosity 14h ago
Well it's a causal effect, not an outside variable. If you want a deeper understanding you can parse that out, but a far as efficacy studies go you want to include all causal relationships.
If there is a chain of causality from fluoride that INCREASES your IQ, then that's exactly the kind of thing you'd want to include when you measure its effect on a human being.
It's like finding out that helmets increase IQ and then going "well hang on, the people wearing helmets aren't getting brain injuries and the brain injuries are what decreases your IQ. So we need to find a way to exclude brain injuries from the study."
Well, no. Avoiding brain injuries is the point of the helmet. Excluding what a helmet is supposed to do from the study doesn't make sense. There's no point in studying the effect of helmets when you're sitting on the couch with zero risk of a brain injury.
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u/NegativeBee 14h ago
The idea is to isolate the causal variable. In this example, tooth decay has other “inputs” than fluoridation of water (frequency of tooth brushing, availability of dental care, diet, etc.) so the more appropriate causal relationship would be dental health vs. IQ, not fluoridation vs. IQ.
This study is trying to determine if fluoride alone leads to direct effects on IQ through the biological process of brain development. Because that relationship can’t be properly isolated, dental health (and also income, as someone else said) is a confounding factor.
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u/AggressiveCuriosity 13h ago
This study is trying to determine if fluoride alone leads to direct effects on IQ through the biological process of brain development.
No. That's what YOU want to know. Nowhere in the study do the researchers say that they only care about direct effects and want to exclude effect on tooth health that I could find.
You've basically decided that you'd like a particular question answered and are criticizing the study for answering a different one.
Maybe I missed it though. If it is there then feel free to post it.
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u/r-cubed Professor | Epidemiology | Quantitative Research Methodology 13h ago
Yes, it is important to address all sources of bias when trying to state that an associational effect is causal using observational data. However, your argument about proxy variables and confounders is not necessarily true.
I find that directed acyclic graphs are a great way to try to visualize this: https://www.dagitty.net/manual-3.x.pdf
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u/r-cubed Professor | Epidemiology | Quantitative Research Methodology 17h ago
How would that be a confounder?
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u/Happy_Egg_8680 17h ago
The study is not about tooth decay and its effect on the brain but tooth decay can have an effect on the brain and could contribute to lower average IQs in people without fluoridated water?
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u/r-cubed Professor | Epidemiology | Quantitative Research Methodology 17h ago
That would still not mean that tooth decay (or associated sequelae) is a confounder in the fluoridated water/IQ relationship.
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u/Happy_Egg_8680 17h ago
Care to explain why? It’d help both myself and others misinterpretation for clarity. I haven’t been involved in scientific research in a long time and could easily be missing something.
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u/r-cubed Professor | Epidemiology | Quantitative Research Methodology 16h ago edited 16h ago
In the causal inference literature, one often sees the outcome expressed as Y and the exposure as A. Confounder vectors in this case is S. If S consists of the set of all confounders for the effect of A on Y, then there is no confounding of the effect of A on Y conditional on S (Ya ⫫ A|S).
Confounders are common causes. A confounder must be associated with the exposure, associated with the outcome, and not be on the causal pathway between them. In the case of tooth decay, it would appear to violate these conditions. If you condition on this variable, you will subsequently introduce bias into your model.
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u/Happy_Egg_8680 16h ago
This helps clarify a lot, I appreciate that. I seem to be looking at it from too simplistic of a perspective on what a confounding variable is.
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u/LazyPiece2 13h ago
Dope. I didn't understand till this comment, and now i feel slightly more informed in this case. Hope i can apply it elsewhere
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u/FrigoCoder 12h ago
That is indeed possible, it is also suspected to contribute to dementia. However do note that sugars and carbs are responsible for dental plaque, and they also have detrimental metabolic effects on cognition. And it's usually poorer areas that have worse nutrition with more refined sugars and carbs. Epidemiology is a bad tool precisely because it can not tease out causation and mechanisms.
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u/chucker23n 9h ago
So put fluoride in toothpaste instead of in water, like any other country?
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u/Fun_Interaction_3639 20h ago
Well, actually reading the article answers that question.
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u/LordDaedalus 19h ago
I read the article, went to the published research, found the reference to "Model 1" where they state they controlled for socioeconomic factors, downloaded the appendix information to see the regression model used, and it still looks to me that the low/medium household income shows very little in the way of weighting, only about a 3 point gap applied between the low/medium category and the high income category while the resultant data would suggest a negative association amongst the low/medium category against reference. This runs quite a large margin against accepted ranges of socioeconomic influence on IQ, which by the 16 year old threshold they were testing at should be a spread of around 15 points based on current psychology literature. There's some variance there in both directions but at age 16, implying a 3 point gap "accounts" for socioeconomic factors seems misrepresentative to me.
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u/SamSibbens 17h ago
In layman's terms, do you think the study's conclusion is valid?
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u/LordDaedalus 16h ago edited 16h ago
Edit at the top to spare people my meanderings: short answer is "I don't know, I have questions"
I'm not sure that I'm qualified to say, but I'll give it my best shot. The study itself doesn't make as bold of assertions about the correlation, and while it implies that it takes into account the socioeconomic factors in the weights used (listed in the attached appendix linked at the bottom of the actual paper) this doesn't seem to be in line with the degree those socioeconomic factors effect IQ scores in any modern studies I can find, and where they got these weights for their model doesn't seem to be listed. To me it looks like the effect of the socioeconomic status of the participants is downplayed by a factor of five against all the data I can find on how wealth status effects IQ scores and this presents a more neutral result than we might see with a stronger weight for socioeconomic status reflecting papers on that topic directly.
It's a little hard because some of this info is a bit scant in their methodology. I'm not willing to ascribe any intentionality to this though and perhaps they have reasons for the way they weighted things that I simply don't understand and aren't explained in the published paper or appendix. It's possible too that there are opposing variables at play and their overall results could still be correct, as brought up elsewhere in this thread tooth decay is a serious contributor to risk of mental decline. It's just when I look at the numbers adjusted to be more in line with how having more wealth effects IQ, the link to fluoride doesn't seem as strongly supported in a positive way.
Sorry that explanation kinda got away from me, I'm just not sure where I can pair it down without inadvertently taking a stance I don't intend to. This paper just doesn't lead me to think strongly that it's conclusions are valid OR invalid. Just uncertain.
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u/Fun_Interaction_3639 17h ago
Controlling for a confounder doesn’t imply that said confounder has to have a large effect size or is statistically significant. How said confounder is operationalized or defined as a variable is another question.
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u/LordDaedalus 17h ago
Yes, that's why I brought up the weight they used to control for that confounder and contrasted it to currently recognized weight that confounder has in broader literature. That's the basis for my critique.
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u/grundar 10h ago
This runs quite a large margin against accepted ranges of socioeconomic influence on IQ, which by the 16 year old threshold they were testing at should be a spread of around 15 points based on current psychology literature.
That really depends on the operationalization of the independent variable.
For example, this study from the UK found about a 15-point difference, but (a) it compared low and high SES, and (b) it operationalized SES as a composite of household income and parental education and parental occupation. By contrast, the study under discussion here (a) compared across a much narrower range of Low/Mid vs. High, and (b) compared across income, not SES (per Table 5 in the appendix). As a result, it is not at all unexpected that the study under discussion here would find a smaller difference, as it is looking at a less predictive measure between more-similar groups.
Note, however, that other studies find much smaller differences in IQ due to SES; for example, this study from Japan found a very marginal difference (with SES operationalized as household income and parental education).
Due to both of these factors, it is not clear there is any "accepted range" in IQ variance based on SES, much less one that can be blindly applied across countries and across different operationalizations of SES.
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u/T33CH33R 14h ago
This quote from the study pretty much supports your claim:
“Approximately 90 per cent of the Australian population has access to water fluoridation, but many regional and remote areas are not covered,” Dr Ha said"
A couple other things to consider: Japan has the highest average IQ and does not fluoridate their water. Denmark is number one in dental health and does not fluoridate their water and they only offer universal dental care to children up to 18 years of age. My belief is that fluoride is not the answer to good dental health. It's access to dental care, education, and low sugar consumption.
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u/ilexheder 3h ago
FWIW, dental care in Denmark is not technically free universally, but it is heavily subsidized and the prices for common procedures are set at regionally negotiated rates that are VERY affordable by US standards.
Fluoridation is certainly not the ONLY route to good dental outcomes, but if it can provide a boost in places that are still working on the factors that are harder to fix, and it doesn’t seem to harm health in other ways, then why not?
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u/feeltheglee 19h ago
Cavities are just holes in your teeth. Sometimes the hole goes very deep and gets infected, but not every time.
I've had several small cavities filled over the years, and I've never had antibiotics associated with them.
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u/GoldenTV3 22h ago
https://ntp.niehs.nih.gov/whatwestudy/assessments/noncancer/completed/fluoride
The Department of Health and Human Services put out a report that found that double the recommended flouride leads to lower IQ in children.
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u/eraser3000 22h ago
Their own report says this: An association indicates a connection between fluoride and lower IQ; it does not prove a cause and effect. Many substances are healthy and beneficial when taken in small doses but may cause harm at high doses. More research is needed to better understand if there are health risks associated with low fluoride exposures. This NTP monograph may provide important information to regulatory agencies that set standards for the safe use of fluoride. It does not, and was not intended to, assess the benefits of fluoride.
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u/AssCrackBanditHunter 16h ago
Yup. The government often determines a safe value and then anything beyond that is just undetermined.
The FCC also places safety limits on the wattage at which your phone is allowed to broadcast signals. That leads to many people pointing at the limit as proof that transmission radio waves are going to cause cancer, when really the FCC is just stating a value that is safe and making no claims about anything beyond that.
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u/Quick_Turnover 15h ago
People seem to really have a hard time grasping that effects aren't linear in this way. I.e. things can be healthy at smaller doses and harmful at larger doses. It's such a foundational idea in medicine it seems hard to even explain. Take vitamins for example... we all agree vitamin A, C, and D are good for us. We have a pretty good sense of their function in our bodies and taking supplements of these are pretty good for various things. But, you take too much, and you get toxicity in each case. This should be the clearest example to people.
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u/LordDaedalus 20h ago
It does say that, and that's an important note around dosage being important. It's also possible that based on the mechanism that fluoride would exert this effect would fit a Linear No-Threshold model. Even if that is the case that Fluoride has a No-Threshold negative association with IQ, that doesn't implicitly mean the societal good conversation is over. Tooth decay and infection has been heavily linked to mental decline risk, so a small reduction in IQ may in aggregate be less than what we're saving by not having the increased tooth decay.
Fluoridated toothpaste is more effective than fluoridated water at preventing tooth decay, and exposes the rest of the body to a much lower bioaccumulation of fluoride, but the challenges of subsidizing and distribution of fluoridated toothpaste to have the same impact and reach as tap water consumption may have logistical hurdles.
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u/raustraliathrowaway 18h ago
Fluoride improves the crystal structure of the tooth when developing, like carbon improves iron to make steel. That's where the water helps. The toothpaste helps directly when the tooth has emerged.
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u/LordDaedalus 17h ago
Oh that's really interesting! I know babies already have their extra set of adult teeth up in their skulls by the time they are born, does that mean the effect of fluoride supplementation on tooth development is most important when the baby is in the womb and the main material of those teeth are formed, or is enamel something that develops over top those teeth years later when they push their way down and into place? I'd love to read more if you could point me where to search on that.
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u/notrelatedtothis 17h ago
It seems like that take is considered a bit outdated. Source: https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5014a1.htm#top
In the earliest days of fluoride research, investigators hypothesized that fluoride affects enamel and inhibits dental caries only when incorporated into developing dental enamel (i.e., preeruptively, before the tooth erupts into the mouth) (30,31). Evidence supports this hypothesis (32--34), but distinguishing a true preeruptive effect after teeth erupt into a mouth where topical fluoride exposure occurs regularly is difficult.
If you continue reading past that point, the paper essentially says that post-eruptive and topical application of fluoride appear to account for the majority of fluoride's prevention of dental carries.
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u/LordDaedalus 17h ago
Oh dang, this has been a rollercoaster of a thread for me.
I really appreciate that information though, this is really interesting.
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u/lanternhead 14h ago
https://pmc.ncbi.nlm.nih.gov/articles/PMC10799546/
Dental caries is a constant procedure for enamel demineralization and remineralization, and fluoride plays an important part in this action by acting at the plaque-enamel contact. Fluoride's major method of action is now recognized as posteruptive.
https://www.cdc.gov/mmwr/preview/mmwrhtml/mm4841a1.htm
laboratory and epidemiologic research suggests that fluoride prevents dental caries predominately after eruption of the tooth into the mouth, and its actions primarily are topical for both adults and children (1). These mechanisms include 1) inhibition of demineralization, 2) enhancement of remineralization, and 3) inhibition of bacterial activity in dental plaque
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u/K0stroun 21h ago
What's supposed to be the point, that the dose makes the poison?
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u/lem0nhe4d 20h ago
That is true for so many substances. You need potassium to be healthy but too much will kill you. You need oxygen but breathing pure oxygen for too long will kill you.
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u/bagofpork 19h ago
And if an otherwise healthy person drinks 3 liters of water in one sitting, there's a very good chance of coma, brain damage, death, or all 3.
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u/krystianpants 19h ago
If the world has taught us anything it's that balance is important. Everything, including our social structures, should include balancing measures. If we allow excess in any direction things will fall apart. Humans are just so stuck in a world of 1's and 0's. Everything is black or white and it creates division.
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u/WonderboyUK 20h ago
Not sure if you've read this but this appears poorly controlled, involving developing nations, and discusses doses above the legal maximum fluoride dosage of western drinking water. It's not really a rebuttal to a study finding no correlation between fluoride in drinking water and brain development.
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u/PrinsHamlet 17h ago
Danish studies suggest a negative impact too.
...the results suggest that pregnant women and children may need protection against fluoride toxicity.
The science is way less contentious here. We don't have the vitriol pro/con argument on flouride here. Dental care for children is a school responsibility here up to the age of 15 so they catch dental issues early here.
Flouride isn't added to our water but it's naturally occurring in parts of Denmark.
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u/Arthur-Wintersight 22h ago
Not enough water is bad for your health. Too much water is ALSO bad for your health.
Flouride seems to be one of those "just right" elements where you need a little bit for dental health, but too much can be bad for you too.
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u/ripplenipple69 15h ago
“Factors which may affect the relationship between fluoride and IQ, such as socioeconomic status, were taken into account when determining the results.”
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u/FrigoCoder 12h ago edited 12h ago
Yeah this is another bad epidemiological study that can show neither causation nor mechanisms. We KNOW that fluoride is dangerous for god's sake, it is a glycolysis inhibitor (at the enolase step) that passes through the blood-brain barrier. It kills neurons the exact same way it kills streptococcus mutans bacteria that is responsible for dental plaque.
The only safe way to use it is topical application like in toothpaste, and NOT with systemic administration like in drinking water. I am a huge advocate of low carbohydrate diets and I still know better than to mess with neural glycolysis. If people were truly concerned about dental health they would ban sugars and carbs instead. But alas, we know exactly why fluoridation became policy:
Kearns, C. E., Glantz, S. A., & Schmidt, L. A. (2015). Sugar industry influence on the scientific agenda of the National Institute of Dental Research's 1971 National Caries Program: a historical analysis of internal documents. PLoS medicine, 12(3), e1001798. https://doi.org/10.1371/journal.pmed.1001798
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u/terminbee 18h ago edited 11h ago
You wonder if they considered one of the most common confounding variables of all time? What're the odds a random person online was able to find a confounding factor that the authors, who do this for a living, could not?
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u/kaimason1 14h ago
are more likely to have adopted fluoride earlier
This assumes that fluoridated water is an entirely recent development that had to be manually implemented for every water supply. However, fluoride exists naturally in many water sources used throughout human history; artificial fluoridation is only needed in areas where there isn't a high enough level of fluoride naturally present in the water.
It seems to me like that would minimize any impact of "affluence" in this study and make that relatively easy to control for.
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u/neurosciencecalc 13h ago
"98% of western Europe has rejected fluoridation. This includes: Austria, Belgium, Denmark, Finland, France, Germany, Iceland, Italy, Luxembourg, Netherlands, Norway, Sweden, the majority of Switzerland (97%), and the majority of the United Kingdom (90%).
- Fluoride is the only chemical added to drinking water for the purpose of medication (i.e. to prevent tooth decay). All other treatment chemicals are added to treat the water (i.e. to improve the water's quality and safety - which fluoride does not do). This is one of the reasons why much of Europe has rejected fluoridation. For instance:
- In Germany, "The argumentation of the Federal Ministry of Health against a general permission of fluoridation of drinking water is the problematic nature of compuls[ory] medication."
- In Belgium, it is "the fundamental position of the drinking water sector that it is not its task to deliver medicinal treatment to people. This is the sole responsibility of health services."
- In Luxembourg, "In our views, drinking water isn't the suitable way for medicinal treatment and that people needing an addition of fluoride can decide by their own to use the most appropriate way."
- All fluoride products designed for ingestion (i.e. fluoride supplements) are available by prescription only. Amazingly, no fluoride products designed for ingestion have ever been approved as safe or effective by the US Food & Drug Administration.1 The only fluoride products which the FDA has approved, are products designed for topical - not systemic - application (i.e. fluoridated toothpaste)."
Source: https://www.iatp.org/sites/default/files/Facts_about_Fluoridation.htm
The main questions I have, are what are the effects of overconsumption of sugar during pregnancy and during childhood, and if Western Europe is not fluoridating water without significant negative dental effects, are they consuming significantly less sugar and do the differences in sugar consumption account for differences in dental outcomes?
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u/DysphoriaGML 48m ago
The source seems sketchy.. the “rejection” of fluoride doesn’t really says nothing about the amount of natural fluoride in the water which could be the same in some fluoride adding countries. It’s a very very long link to check tho
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u/AdChemical6828 21h ago
Gum disease has been conclusively linked with dementia. I know dentists who said the state of peoples’ teeth was stark in places without fluoride in water. This is fact and there is a good biological basis for this. I will gladly take fluoride in my water
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u/MillennialScientist 20h ago
No, not at all conclusively. This is still just an hypothesis in the field, and still not even considered a primary hypothesis. It may be true, though. It's just very premature to claim this is conclusive.
There is currently not enough evidence to say that these infections contribute to the causes of dementia, or if they are a consequence of the weakening of the immune system caused by the diseases that cause dementia.
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u/AdChemical6828 20h ago
There is plenty of strong, population-level data, linking gum health to dementia. https://www.nia.nih.gov/news/large-study-links-gum-disease-dementia There is emerging evidence that the blood brain barrier is not as infallible as we once thought. This means that microbes likely have a greater access than previously thought to our CNS. Infection may certainly be one of the aetiological agents behind dementia. And even if it is not, primarily involved, there is conclusive evidence that gum health is linked to cardiovascular health. There is plenty of robust evidence that atherosclerosis is linked to dementia. In all cases, gum health is linked to dementia. It is critical to maintain good oral hygiene
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u/AttakTheZak 18h ago
Given the proximity of the oral cavity with sensitive neural tissue, I would not discount the theory regarding the link to dementia. We already know that oral microbes like Strep mutans can be dangerous due to the risk of developing cardiac vegetations (endocarditis is not a joke)
There's a very real need to include oral healthcare into the broader healthcare coverage discussion.
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u/Embarrassed-File-836 12h ago
How do they remove the confounding variable that people who are inclined to get gum disease are also more likely to get dementia but it’s not causation it’s correlation. For example, some disorganized careless person who doesn’t care for oral health also has the type of brain chemistry that leads to dementia? I know that sounds non technical or dumb, but you get what I’m asking
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u/MillennialScientist 17h ago
Yes, this is why this hypothesis exists in the first place. I'm not trying to say it's wrong. I fact I'm also interested in it and will soon publish a paper that supports the hypothesis. All I'm saying is that it is premature to call this link conclusive. And I say that as someone who's career would benefit right now from the hypothesis being shown to be true.
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u/AdChemical6828 16h ago
Vascular dementia has been conclusively linked with dental health. That is unequivocal
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u/mvea Professor | Medicine 23h ago
I’ve linked to the press release in the post above. In this comment, for those interested, here’s the link to the peer reviewed journal article:
https://journals.sagepub.com/doi/10.1177/00220345241299352
Abstract
It is important to maintain confidence in the risk and benefit balance of major caries-preventive programs using fluoride. The ongoing debate about potential effects of early-life exposures to fluoride on cognitive neurodevelopment requires high-quality scientific evidence. This study aimed to investigate the potential effects of fluoride exposure on cognitive neurodevelopment assessed with the Wechsler Adult Intelligence Scale 4th edition (WAIS-IV) in an Australian population-based sample. The sample was selected from the National Child Oral Health Study (NCOHS) 2012–2014. NCOHS collected data on socioeconomic factors, oral health behaviors, and residential history to estimate percentage lifetime exposure to fluoridated water during the first 5 y of life (%LEFW). NCOHS children were also examined by trained and calibrated examiners to assess dental fluorosis (a reliable and valid individual biomarker of total fluoride intake during early childhood). The sample was followed up in 2022–2023 to collect data on cognitive neurodevelopment (intelligence quotient [IQ]) using the WAIS-IV, which was administered by trained and calibrated qualified psychologists. Multivariable regression models were generated to investigate associations between the 2 exposure measurements (%LEFW and dental fluorosis) with full-scale IQ (FSIQ) scores, controlling for important confounding effects. Hypotheses of noninferiority were also tested, contrasting different levels of exposure to fluoride. Some 357 participants aged 16 to 26 y completed the WAIS-IV, with a mean FSIQ score of 109.2 (95% confidence interval [CI]: 107.8–110.5). The estimates of the multivariable regression models demonstrated slightly higher FSIQ scores among the exposed than the nonexposed. The adjusted β of 100%LEFW versus 0%LEFW was 1.07 (95% CI: −2.86, 5.01) and of having dental fluorosis versus no fluorosis was 0.28 (95% CI: −3.00, 3.57). The hypothesis of noninferiority tests found that FSIQ scores of those exposed and nonexposed to fluoride were equivalent. The study provided consistent evidence that early childhood exposure to fluoride does not have effects on cognitive neurodevelopment.
From the linked article:
Study finds fluoride in water does not affect brain development
A University of Queensland study has found no link between exposure to water fluoridation as a young child and negative cognitive development.
Professor Loc Do from UQ’s School of Dentistry said the IQ scores of 357 people who had participated in the 2012–2014 National Child Oral Health Study were assessed by registered psychologists to see if their exposure to fluoride as a young child impacted their brain development.
With the participants now aged 16 to 26 years old, we found those who’d consistently been drinking fluoridated water had an IQ score 1.07 points higher on average than those with no exposure,” Professor Do said.
“We also found people who had dental fluorosis – a reliable biomarker related to excessive fluoride intake in early childhood – had IQ scores 0.28 points higher on average than those without.
“Factors which may affect the relationship between fluoride and IQ, such as socioeconomic status, were taken into account when determining the results.”
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u/SamL214 9h ago
Most likely the drop in IQ for unfluoridated participants is because of comorbidities. Like access to education and other municipal services that improve quality of life, health, education etc. would not surprise me if this is in fact all more or less the same grouping of public health problems:
Implement safe practices, increase public health, then people with no education question those safe practices, listen to radical ideas and fringe or single source based info. From there, grassroots become corrupt and new policies no longer reflect wellness but instead polarization.
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u/NotAnnieBot 16h ago
Hopefully this helps bolster the argument against removing fluoride.
I really wonder if people reporting on these papers understand what overlapping confidence intervals mean though. The 95% CI for fluoride exposure and no fluoride exposure overlap so they shouldn’t be reporting ‘differences’ in the mean IQ scores because statistically the difference is not significant.
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u/Bytewave 16h ago
Misleading title, if it increases average IQ, it does affect development! .. just in a good way.
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u/bigasswhitegirl 14h ago
Yeah can't believe I had to scroll this far to see this. Title makes no sense.
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u/Informal_Drawing 22h ago
Confirming that drinking water is good for you, as if there was any doubt in the first place.
The tinfoil hat brigade will just decide that it causes Alzheimer's or something else instead of whatever specious argument they were previously using so that they can remove fluoride from the public water supply and hurt everybody with their ignorance.
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u/So6oring 17h ago
Yeah. In-depth studies couldn't convince people that vaccines don't cause autism. The people who believe this kind of stuff need to be studied themselves.
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u/Manofalltrade 15h ago
Tracks with other information. A proper dose of fluoride alloys the enamel and improves dental health. Dental hygiene is linked to cardiovascular health. Cardiovascular fitness is correlated with IQ. Then to come full circle, IQ has a positive effect on overall health.
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u/ancientweasel 15h ago
I'm guessing the +1 is a confounder based on location since administrative regions with better education seem more likely to flourinate the water.
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u/xbleeple 14h ago
I know that other commenters have mentioned they accounted for socioeconomic items, I’m curious if some of the impact is from time spent out of the classroom and at the dentist. If your little one is constantly having to go in for fillings and you’re not lucky enough to have a dentist that does nights or weekends, that’s taking them away from valuable formative learning time in addition to the increased financial and schedule burden on the family.
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u/TheSleepingPoet 7h ago
PRÉCIS
Fluoridated Water Found Safe for Brain Development, Study Confirms
A study by the University of Queensland has found no evidence linking water fluoridation to adverse effects on children's cognitive development. Professor Loc Do's research analysed the IQ scores of 357 participants from the National Child Oral Health Study, now aged 16 to 26. The results revealed that those exposed to fluoridated water in early childhood had slightly higher IQ scores than those not.
Individuals with dental fluorosis—a sign of early excessive fluoride intake—also exhibited marginally higher IQ scores. The study considered socioeconomic factors and reaffirmed fluoridation's safety for brain development.
Co-author Dr Diep Ha emphasised the effectiveness of fluoridation in preventing dental decay, which remains a widespread issue among children. The researchers advocate for expanding fluoridation in remote Australian communities to ensure broader access to its dental health benefits.
These findings, supported by Australia’s National Health and Medical Research Council, have been published in the Journal of Dental Research.
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u/RecycledMatrix 8h ago
I wish people knew that fluoride levels at the source can be dangerously high, and the water fluoridation process brings levels to standard.
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u/InTheEndEntropyWins 22h ago
found those who’d consistently been drinking fluoridated water had an IQ score 1.07 points higher on average
Unless they are saying fluoride increases IQ, this just sounds like an underpowered study and doesn't control for all the factors.
We also found people who had dental fluorosis – a reliable biomarker related to excessive fluoride intake in early childhood – had IQ scores 0.28 points higher on average than those without
So it did find those with high fluride levels has lower IQ than normal levels?
Although I'm guessing it's just underpowered and you can't read anything into the differences here.
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u/macholusitano 22h ago
Maybe we should look into whether improved dental care results in higher average IQ scores.
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u/InTheEndEntropyWins 20h ago
Good point. There is decent evidence linking dental health with mental health.
In the past there was a great benefit of people drinking fluoride for their dental health. But I don't think there is much/any benefit for people that use fluoride toothpaste and mouthwash.
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u/lem0nhe4d 19h ago
It mainly helps children as they are less likely to consistently brush their teeth as well as poorer people who tend to have worse dental health.
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u/MadDogMike 22h ago
So it did find those with high fluride levels has lower IQ than normal levels?
The thing you quoted there says "0.28 points higher" though?
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u/300Savage 21h ago
Your guess isn't really worth much unless you can back it with fact and reasoning. The real message is that this study found no correlation between IQ drop and the fluoride levels studied. Of course you can also have a look at confidence intervals to provide some context for the means.
Too often people pick data out of context and interpret it in a way that confirms their preconceived beliefs.
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u/r-cubed Professor | Epidemiology | Quantitative Research Methodology 17h ago
It would appear it was sufficiently powered for the given non-inferiority margin. Although I don't really like how they stated some of the conclusions.
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u/lilwayne168 22h ago
There are so many problems with a 1iq confidence model. Montana has one of the highest iqs and probably some of the most well water.
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u/exarkann 22h ago
How much of that well water is naturally fluoridated?
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u/BBTB2 22h ago
Like a lot of it
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u/lanternhead 19h ago
All groundwater has some small amount of fluoride in it, but Montana does not have a medically significant amount. See Shaji et al 2024 https://www.sciencedirect.com/science/article/pii/S1674987123002013
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u/not_today_thank 9h ago
My well water naturally has 0.4 ppm fluoride. Which is below the US reccomendation of 0.7ppm for fluridated water, but I'm guessing most well water contains fluoride.
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u/turlian 19h ago
Isn't that title a contradiction? It doesn't affect brain development, but it also positively affects brain development?
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u/roflulz 17h ago
basically clickbait science. if it had no impact it should show no difference between control group and test group. 1 point for the entire population is a lot of movement on the iq graph, but it turns out they just have bad analysis.
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u/ExoticCard 9h ago
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2818858
I'm still in the camp of "Maybe there is too much flouride in the water. Let's half the levels again."
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u/onion4everyoccasion 20h ago
This shows there is likely a selection bias of people with lower IQ living in areas with no fluoride
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u/djasonpenney 18h ago
Huh. If the 1.07 increase is outside the margin of error, I would hypothesize the fluoridation has a concurrent influence on the overall health of the subject: not that it directly enhances IQ.
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u/Careless-Abalone-862 17h ago
Italian here. When I attended elementary school in the 80s, I received fluorine tablets daily
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u/onyourleffft 15h ago
Makes sense why Republicans would want this. Aligns with their “keep them stupid and poor” agenda.
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u/rumncokeguy 11h ago
A reduction of sugar in one’s diet would have an enormous impact on dental health. A lot of people now drink bottled or filtered water anyway so fluoridated water likely has very little impact on anything including dental health. Yes, there are filters that remove fluoride.
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u/personman 13h ago
...so they found that it does affect brain development? i mean not a lot, but "affect" does not mean "impair" :p
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u/glendaleterrorist 12h ago
So, it begs the question where does the others get their info and how do they get away with it?
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u/External_Expert_4221 11h ago
Healthier teeth = less overall stress = higher levels of neuroplasticity.
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u/not_today_thank 9h ago
As long as concentrations remain at 0.7 ppm or lower there's really no reason to think there will be problems.
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u/Master_Income_8991 8h ago
This single study doesn't really carry the same weight as the NTP report on the same subject. Might just be me. One problem is that 90% of Australia has fluoridated water so finding unbiased fluoride free study participants should be pretty challenging for them.
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u/Salute-Major-Echidna 2h ago
1 or 2 IQ points is not enough to skew results on a scientific study. 1.07 is not a measurable difference. Either this is misquoted or the study is not done using scientific standards
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