Those who drink water with U.S.-recommended levels of fluoride during childhood may perform better on cognitive tests in high school. The large study of U.S. sophomore and senior students was recently published in Science Advances.
It is believed to be the first longitudinal, population-based study to investigate the cognitive outcomes of people exposed to recommended levels of fluoride in the U.S., the authors wrote.
“We find robust evidence that young people who are exposed to typical, recommended levels of fluoride in drinking water perform better on tests of mathematics, reading, and vocabulary achievement in secondary school than their peers who were never exposed to sufficient levels of fluoride,” wrote the authors, led by John Robert Warren of the Institute for Social Research and Data Innovation at the University of Minnesota in Minneapolis (Sci Adv, November 19, 2025, Vol. 11:47, eadz0757).
In the U.S., the long-standing public health practice of adding fluoride to public water systems to fight tooth decay is being heavily scrutinized following a study that found a correlation between high levels of fluoride exposure and lower IQ in children. However, this study explored fluoride exposure that was at least twice the U.S.-recommended limits. Other research has shown that this study may be flawed.
Additionally, the debate has heated up since U.S. Department of Health and Human Services (HHS) Secretary Robert F. Kennedy Jr. called fluoride “an industrial waste” in promises to roll back U.S. recommendations that fluoride be added to community drinking water systems. water. In 2025, Utah and Florida banned community water fluoridation.
In November 2025, the U.S. Food and Drug Administration moved to restrict the use of prescription ingestible fluoride supplements in children under the age of 3 or older children who are at a moderate or lower risk of tooth decay.
For the current study, nearly 27,000 people were followed for more than four decades since they were sophomores and seniors at U.S. high schools in the 1980s to explore how children’s fluoride exposures may be associated with cognitive test performance in adolescence. Based on historical data from HHS and the U.S. Geological Survey, researchers explored how individuals performed on math, reading, and vocabulary tests and how their performance potentially tied to their exposure to recommended levels of fluoride in community drinking water. Between 1962 and 2015, HHS water fluoridation levels ranged between 0.7 mg/L and 1.2 mg/L. In 2015, HHS lowered that recommendation to 0.7 mg/L.
Compared to individuals who had no exposure to fluoride, those exposed to fluoride for part of their childhood had higher test scores in secondary school. Individuals exposed to fluoride for their entire childhood performed better on tests, the authors wrote.
Nevertheless, the study had limitations, including not having complete information about where students lived from the time they were born through late adolescence. Researchers had to place them in the communities in which they went to high school, the authors wrote.
“Our results provide strong evidence that exposure to fluoride -- at levels ordinarily seen in the United States and of relevance to policy debates about municipal water fluoridation -- has benefits for adolescent cognition,” Warren and colleagues wrote.
