Fluoride during Pregnancy and Infancy
Below is a summary of this issue - if you’re interested in more detail on the research, check out my data deep-dive (aka the full nerd version)
Background
Fluoride occurs naturally in water and food
In 1945, the US began introducing more fluoride into public water systems to help prevent cavities, which were extremely common at the time, especially among children (this is before fluoride toothpaste was available)
Today, about 73% of the US population use water systems with added fluoride (source)
Dental outcomes in the US have improved over time but similar improvement is also observed in countries that don’t fluoridate
98% of Europeans drink unfluoridated water and have similar, if not better, dental outcomes as we do (the UK is one of the few countries that does fluoridate and they’re not exactly known for their great teeth…)
The below graphs from an excellent Atlantic article illustrate this point
This has caused some to speculate that access to fluoride toothpaste and better dental care are sufficient to prevent cavities, and water fluoridation may no longer be necessary
Indeed, topically applied fluoride (i.e. toothpaste, fluoride at the dentist) can reduce cavities irrespective of exposure to water fluoridation (source)
Research
Concern over the risks associated with fluoride exposure - particularly on the developing brain - have long been downplayed by public health officials
However, enough research has accumulated that as of August 2024, the National Toxicology Program (NTP), part of the US Department of Health and Human Services, just published their own report:
“This review finds, with moderate confidence, that higher estimated fluoride exposures are consistently associated with lower IQ in children.”
Studies in the report that occur in areas with fluoride levels similar to the US (Canada, Mexico City) find small but significant effects of around two to five IQ points (the IQ scale ranges from intellectual disability at 69 to genius at 130)
Some studies mentioned in the report find small adverse effects on other cognitive measures too, such as ADHD rates (study)
The IQ impact seems to be greatest when looking at fluoride exposure prenatally via placenta transfer; the next highest impact period is infancy, when water is mixed with formula (study)
This may be because the “blood brain barrier” that protects the brain from toxins isn’t fully developed yet at these early stages
Exposure during childhood - through drinking water - shows the same inverse pattern with IQ, but the effect is weaker
However, research on toothbrushing finds that adults significantly overdose children’s toothpaste amount (by 6-7x!) (source) and young children swallow most (if not all!) of the toothpaste, especially when it’s a yummy flavor (source)
Use of fluoride toothpaste combined with fluoridated water could increase risk of overexposure during early childhood
Recommendations
First off: don’t panic! At the fluoride levels in most of the US water systems, the impact is relatively small.
But it’s also relatively easy to make some changes if you’d like to minimize fluoride exposure going forward
Look up your county’s fluoride status (if non-fluoridated, this is a non-issue)
During pregnancy:
Consider switching to drinking non-fluoridated water, especially if you’re having a boy, as some studies find they are particularly vulnerable in utero (source)
You can buy large amounts of bottled water, or set up a delivery service of 5-gallon bottles to use with a dispenser, like you see in office break rooms
Look for “spring water” which only contains the naturally occurring amount of fluoride
You don’t want “distilled water” which has removed all the minerals, including good ones (like calcium, potassium, magnesium)
But if you’re planning to use non-fluoridated water for a longer period of time (formula feeding, toddler’s drinking water, future pregnancies), may be worth investing in a longer-term solution: have a plumber install a reverse osmosis filter under your sink
This device takes out all the minerals and then adds back only the ones we want to keep
It doesn’t produce waste the way that water bottles do
It does require some replacing of parts, but no more often than every 6 months
Regular water filters don’t remove fluoride, and neither does boiling water
Don’t stress about consuming fluoride water when you’re outside your home (at a friend’s, a restaurant) - this is about reducing your average, not avoiding 100%
Refrain from having too much black and green tea, which contains high fluoride content - you can look up the fluoride levels in particular types/brands here
I wouldn’t be too concerned about fluoride toothpaste since adults spit most of it out and the amount that is absorbed is minimal
Systemic fluoride (i.e. fluoridated water) enters the bloodstream (and thus crosses the placenta) and reaches the teeth via saliva, whereas topical fluoride (i.e. toothpaste) strengthens tooth enamel directly and is fairly localized
However, if you’re interested, fluoride-free adult toothpastes are available
During formula-feeding:
I strongly recommend mixing formula with fluoride-free water
When babies consume tap water, the amount of fluoride relative to their body weight is much higher than adults (part of what makes water fluoridation a crude strategy since it’s the same concentration regardless of age and size)
Since babies don’t have teeth (or have very few), there is little downside to limiting their fluoride exposure
Again, boiling the water doesn’t remove fluoride, so you’ll need to either use bottled water or install a reverse osmosis filter
During breastfeeding, very little fluoride passes through the milk so don’t worry about that
During early childhood
The official recommendation from the AAP (which your pediatric dentist will likely echo) is to begin brushing babies teeth twice daily as soon as the first tooth erupts, and to use a tiny smear of fluoride toothpaste until age 3
But given the potential risk of too much fluoride, and the reality that children swallow a ton of toothpaste (and parents often apply more than a tiny smear), I suggest either limiting fluoridated water or limiting fluoride toothpaste, or both if you want to be extra cautious
In balancing risks of fluoride with benefits, keep in mind that some people are just more genetically susceptible to cavities than others - the various studies on this issue estimate heritability to fall between 20-65% (source)
So if you or your partner are prone to cavities, you may want to be more cautious with your child
Do cavities in baby teeth matter even since they fall out anyway? They can in fact still cause pain, lead to infection, and - in the rare occasion that they require removal - result in misalignment of permanent teeth
If you’ve already installed a reverse osmosis filter during pregnancy, might as well continue using it for your young children
Just like during pregnancy, if your child drinks non-fluoridated water at home, don’t worry if they occasionally have fluoride water outside the home
Stick to fluoride-free toothpaste until your child is capable of spitting (usually around age 4-5)
For really little ones, these Dr Brown dental wipes are a nice alternative to toothbrushing (and are fluoride-free)
Fluoride-free toothpastes: Dr. Brown’s for babies, Tom’s for ages 3+, Boka
These contain different chemicals - Xylitol, Hydroxyapatite - which are also known to reduce cavities but pose less risk (source)
Once they are old enough for fluoride toothpaste, monitor the amount put on the toothbrush - “pea size” is smaller than you think!
Engage in other practices that prevent cavities and carry little downside: limit sugary foods/drinks, have children drink water after meals (helps dislodge food), and visit the dentist annually
The most common location of cavities in young children is the front top teeth, so make sure to brush/wipe this area
I highly recommend Fairlife milk which goes through a filtration process that decreases sugar content by 50% and increases protein by 50% - double win!
Don’t serve juice, it’s just not worth it - milk and water only!
If you’re interested in going deeper on my analysis of the data, check out the full nerd version
