Fluoride in infant formula: what the 2009 JADA study found

The question the study asked

Powdered and liquid concentrate formulas are made up with water. For a baby who lives mostly on formula, that water is a large share of everything they drink, and they drink a lot of it for their body weight. So the fluoride in a family's tap water reaches a formula-fed baby in larger amounts, relative to size, than it reaches an older child or an adult.

According to the study's own introduction, a 2006 National Research Council report cited studies that raised the possibility that some babies could be getting more fluoride than intended this way, while their teeth were still forming. The American Dental Association issued interim guidance in response, and its own researchers then set out to put numbers on it.

What Siew and colleagues found

The study is Siew and colleagues, "Assessing a potential risk factor for enamel fluorosis: a preliminary evaluation of fluoride content in infant formulas," published in the Journal of the American Dental Association in October 2009 (volume 140, issue 10, pages 1228–1236). The authors were researchers at the ADA and at Loma Linda University. You can read it at the journal through its DOI, and the abstract is on PubMed.

They measured fluoride in powdered, liquid concentrate and ready-to-feed formulas. Then they estimated how much fluoride a baby would take in, by combining those measurements with water at several fluoride levels and with published recommendations for how much babies drink. They compared the estimates with two reference values from the Institute of Medicine: a tolerable upper limit and an adequate intake level.

In summary, they reported that:

• The formulas themselves were low in fluoride. Mixed with low-fluoride water, none of them would push intake past the upper limit.
• Fluoridated water changed that. The abstract reports that some babies from birth to six months whose main food was powdered or concentrate formula mixed with 1.0 ppm water were likely to exceed the upper limit. The results section puts the range wider: some babies were likely to exceed it with water from 0.7 to 1.0 ppm, and only with water below 0.5 ppm were most babies likely to stay under it.
• The discussion goes further than the abstract. There the authors wrote that most babies from birth to 12 months who live mainly on powdered or concentrate formula are likely to exceed the upper limit when it is mixed with optimally fluoridated water (0.7 to 1.2 ppm). That assumes formula feeding through the whole first year.
• The limit itself has uncertain meaning. In the same passage the authors noted that how well this upper limit protects against moderate-to-severe fluorosis is uncertain, and elsewhere that they do not know the significance of exceeding it.
• Very low-fluoride water has its own gap. When the mixing water was below 0.4 ppm, babies from six to twelve months were likely to take in less than the adequate intake level.

What the study did not show

The authors called it a preliminary evaluation, and the limits matter when you read it.

It estimated intake from feeding guidelines rather than measuring what real babies drank. It did not examine any child's teeth, so it does not show how often fluorosis actually followed. It tested 49 formulas bought in the Chicago area at the time, which are not necessarily the formulas on the shelf today. The authors did report that their formula measurements were generally in line with earlier studies, so the water is the part that varies most.

The water levels it modeled still matter. In 2015 the U.S. Public Health Service set its recommended level for community water at 0.7 milligrams per liter, which is inside the 0.7 to 1.0 ppm range where the study found some babies likely to exceed the upper limit. The EPA began an expedited review of fluoride in drinking water in 2025, and local utilities decide whether and how much to fluoridate, so check your own water's level rather than assuming it.

What enamel fluorosis is

Enamel fluorosis is a change in how tooth enamel looks, usually faint white flecks, spots or lines. It forms only while teeth are developing under the gums. The CDC's page on dental fluorosis says it is mostly mild and cosmetic, that it does not affect how teeth work, that moderate and severe forms are rare, and that older children, teens and adults cannot develop it.

What the CDC and the ADA say now

In 2011 an ADA expert panel reviewed the evidence on this question (Berg and colleagues, JADA 2011). It said dentists advising parents of babies who live mainly on powdered or concentrate formula can suggest continuing to mix it with optimally fluoridated water, while being aware of the potential risk of enamel fluorosis. It also said that when the risk of fluorosis is a concern, dentists can suggest ready-to-feed formula, or powder or concentrate mixed with water that is fluoride-free or low in fluoride. The panel presented these as a resource for clinical decisions, to be weighed with the professional's judgment and the family's own needs and preferences.

The CDC's fluoridation FAQ says formula mixed with fluoridated water may increase the chance of mild fluorosis when formula is a baby's main source of food, and that ready-to-feed formula contains little fluoride. It says bottled water labeled de-ionized, purified, demineralized or distilled has little or no fluoride unless fluoride is listed as an added ingredient, and that parents can use that kind of water some of the time to lower the risk.

Neither organization tells parents to stop using fluoridated water for formula, and the CDC notes that fluoride in water helps prevent cavities.

Questions worth taking to your pediatrician or dentist

This page explains a study. It is not advice about what to feed your baby, which depends on your child, your water and your doctor's view. If you want to talk it through, these are useful things to bring:

• The fluoride level in your water. Community systems publish it in their annual water quality report. Our guide to testing your tap water explains how to read that report. A private well is not covered by one, so its fluoride level is only known if the water is tested.
• How your baby is fed. Breast milk, ready-to-feed formula, or powder or concentrate mixed with water, and roughly how much.
• Other sources of fluoride, such as toothpaste once teeth arrive, or supplements.

Why this page exists

SafeMama hosted a PDF copy of this article for many years, and other sites linked to it. The article is the American Dental Association's copyrighted work, so we have taken our copy down, and the old link now leads here. To read the original, use the journal link above.