Let me start by saying that I am 100% team fluoride. Fluoride is available in oral healthcare products, some drinking waters, and as prescription drops or chewable tablets. It offers cavity preventive effects when delivered both topically or systemically at appropriate times and doses and I love that it is cheap, simple, and easily accessible. As a pediatric dentist, I have seen the impact of severe cavities on children (google Deamonte Driver out of Maryland – he died of a tooth abscess that went to his brain), so I am all for any public health measure that may help reduce that kind of suffering. That said, I do believe there is some misunderstanding surrounding the reconstitution of infant formula with water that contains fluoride, and many of you asked me to explain fluorosis risk and how that relates to the water used to reconstitute formula.
Why is the water used to reconstitute baby formula important?
Babies are small and vulnerable, with their immune systems still coming online in the first few months. This is why the most important consideration when it comes to infant formula reconstitution is that the water is clean. If your choice is between water without fluoride versus water that is clean but fluoridated, always always always choose the clean water. The WHO recommends boiling tap, bottled, or well water before reconstituting infant formula (this is due to a lack of regulatory control over water purity in some countries). In the US, it’s generally recommended that well water (or any water of uncertain cleanliness) be boiled before reconstituting infant formula. Another concern with well water is nitrate level (consumption by young infants is linked to methemoglobinemia), so if you’re on well water, have nitrate levels checked every 3 months. I would personally still choose to boil tap water for formula reconstitution until the child reaches 6 months of age and begins taking solids and drinking tap water, although this isn’t a formal recommendation. The purpose of boiling is to ensure there are no contaminants that could harm the baby.
What does the type of water used have to do with fluorosis?
The concern about water type and fluorosis centers around the fluoride dose present in water. A relatively higher amount of systemic fluoride exposure in early infancy (because the dose is by weight, and babies are small) may place the child at higher risk for enamel fluorosis of the permanent teeth. For some parents, this is concerning, but for others, this is a small risk they’re willing to take for either potential cavity preventive benefits (mild fluorosis reduces enamel’s susceptibility to acid breakdown and thus decay) or for the cost and convenience (tap water is easily accessible and free). What you decide to do is really up to you – there’s no right or wrong answer. I just want to give you the information and you can decide what’s right for your family.
What is dental fluorosis?
Fluorosis of the enamel occurs when a higher than ideal level of fluoride is ingested and then incorporated into the enamel of the developing teeth. Since fluoride is everywhere and occurs naturally, it’s hard to point directly at the use of fluoridated water for infant formula reconstitution and say that it contributes to the development of fluorosis, but it’s possible that it has an impact. Fluorosis can range from mild (smooth white flecks) to severe (pitting and brown defects). Mild fluorosis is the most common, with the more severe form typically occurring in cases of contaminated well water or the ingestion of excessive amounts of toothpaste (think stealing the tube for midnight snacking). The good news is that mild fluorosis results in teeth that are more resistant to decay, but some people find the appearance of the teeth to be visually displeasing.
How can fluorosis occur when I reconstitute baby formula with water that contains added fluoride?
When it comes to infant formulas, most already contain fluoride in the range of 0.15 to 0.20ppm (parts per million). Studies examining the milk of a mother who drinks fluoridated water (at the level of 1.0ppm, the average municipal fluoride level prior to 2015) found the amount of fluoride present in her milk to be an order of magnitude smaller than that of formula, 0.01ppm. The theory goes that if fluoridated water is utilized to reconstitute infant formula that already contains fluoride, the total amount of fluoride ingested may then be high enough to result in mild fluorosis of the developing permanent teeth of the infant. Again, this isn’t a certainty, but a logical possibility; so for those who wish to minimize the risk of fluorosis, there are other options.
In my area of practice in rural Virginia, the fluoride levels in well water are low and the city water fluoridation level is at the standard level of 0.7ppm recommended by the Department of Health and Human Services since 2015. This being the case, I recommend that my patient families that wish to minimize the infant’s risk of fluorosis of the permanent dentition (and hear me – this is not a value judgment – I do not have an opinion one way or the other as to whether or not this decision to avoid fluoridated water is superior to using water that contains fluoride) avoid reconstituting infant formula with bottled waters containing added fluoride (e.g. Nursery WaterTM pink label, which contains up to 0.7ppm added fluoride – notably they have a version with a purple label that is fluoride free) and instead use water processed via “reverse osmosis” or “steam distillation”. Both steam distillation and reverse osmosis filtration remove most if not all of the fluoride content. Note that “ozonation” does NOT remove fluoride, it is simply a disinfection process, not a filtration process. Many “natural” Spring waters are processed via ozonation only and not heavily filtered (i.e., by reverse osmosis or steam distillation), and given that fluoride is a naturally occurring mineral, it may still be present in the spring water. You’d want to check the fluoride levels with the company before using it to reconstitute formula.
The use of tap water depends on the family’s desires because its levels are now standardized nationwide (0.7ppm), and the cost and convenience of tap water may outweigh the small risk of fluorosis. So please hear me in the back – when I mention a family’s decision to avoid using tap water or fluoridated bottled water to reconstitute formula – I am not making a value judgment; I am simply providing information and allowing each family to decide what they want to do.
Why does bottled fluoride water that’s marketed for infant use even exist?
Nursery Water and others like it exist because tap water and bottled fluoridated water are excellent choices for drinking water, especially if a family doesn’t have access to fluoridated water (e.g. they live on a well or in a city without fluoridated municipal water). Once a child begins to practice using an open cup and drinking water (which on average is around 1 year that they’re taking in any considerable amount), I do recommend offering fluoridated drinking water, whether that be Nursery Water or tap water, because the amounts consumed are small and the child is now larger, meaning the dose is relatively less. Drinking fluoridated water throughout the day has been shown to reduce cavity risk in children by 30 percent compared to their peers who drink unfluoridated water. But fluoride use in young children is always a balance between the risk of fluorosis and the risk for cavity formation, which is why it’s important to discuss your family’s individual situation with your personal dentist.
In conclusion, reconstituting infant formula with water that is low in fluoride content (e.g. water processed via reverse osmosis) may reduce a child’s risk for dental fluorosis of their permanent dentition, especially in the first few months of life when the formula is the sole source of nutrition and the child is small. For parents who wish to minimize the risk of fluorosis as much as possible, I recommend reconstituting with water processed via reverse osmosis OR steam distillation (bottled water will list these methods on the label under how it was processed). For some families, fluorosis if of little concern and tap water is easiest and cheapest to come by, and using that water to reconstitute infant formula is not a wrong choice. As with most things in parenting, choosing what is best for your family is a balance, and decisions are made based on the individual family’s priorities, concerns, and circumstances.
