In August 2024, a US federal report sparked heated discussions. Fluoride, added into water to prevent cavities, was linked to slightly lower IQ in children. Although the report only reported “moderate” confidence in the findings, the conclusion was obviously concerning.

Now, a new study presents a contrasting conclusion. Researchers found no disadvantage associated with fluoride usage; in fact, children whose water was fluoridated had an IQ score higher by 1 point on average.

Fluoride, a common element in water fluoridation programs and toothpaste, is excellent at preventing dental caries. Yet, it has also sparked decades of debate over its potential effects on child neurodevelopment.

The developing brain, particularly during infancy and early childhood, is sensitive to chemical exposure. Critics of fluoridation often cite studies suggesting potential neurotoxic effects. For instance, the National Toxicology Program (NTP) initially flagged fluoride as a developmental hazard but later revised its stance following criticism of inadequate evidence.

The new study analyzed the IQ scores of 357 people aged 16-26 who had participated in the 2012–2014 National Child Oral Health Study in Australia. Cognitive performance was assessed using the Wechsler Adult Intelligence Scale, 4th Edition (WAIS-IV), a comprehensive and reliable tool. Researchers also controlled for variables like socioeconomic status, breastfeeding duration, and neurodevelopmental diagnoses, ensuring the robustness of the findings.

The study found no evidence linking fluoride exposure during early childhood with adverse cognitive outcomes. Participants exposed to fluoridated water and those with dental fluorosis scored comparably on full-scale IQ (FSIQ) tests. In fact, participants with fluoridated water tested slightly higher on the IQ scale, says Professor Loc Do from the University of Queensland, who carried out the research.

“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.

“There have been claims water fluoridation can negatively affect children’s neurodevelopment, but these results provide consistent evidence this is not the case.”

IQ and fluoride

Not all countries fluoridate their water. The practice of adding fluoride to public water supplies varies widely. Countries like the United States, Canada, Australia, and parts of Ireland actively fluoridate water to prevent dental caries, backed by strong evidence of its benefits. However, many European nations, including Germany, Sweden, and the Netherlands, do not fluoridate water, often citing sufficient natural fluoride levels or a preference for alternative public health measures.

The findings offer critical reassurance to policymakers and public health advocates. Community water fluoridation has been repeatedly validated as an effective strategy for preventing tooth decay. The only question now is whether there actually is any link to cognitive harm. This new study says there isn’t.

“Approximately 90 percent of the Australian population has access to water fluoridation, but many regional and remote areas are not covered,” said co-author Diep Ha.

“Dental decay or cavities are the most common chronic childhood disease worldwide, which can be quite painful, and teeth often have to be removed. Fluoridation is very effective in preventing these issues, and this research provides reassurance that it is safe to be expanded into more communities.”

Despite the scientific consensus, public skepticism about fluoride persists, fueled by misinformation and inconsistent messaging. This is doubly important as Trump’s health pick, Robert F. Kennedy Jr., has also repeatedly mentioned he wants to remove fluoride from water.

Based on this recent research, the benefits of fluoride in reducing dental caries and promoting oral health far outweigh unsubstantiated risks. Given the study’s rigorous design and alignment with global research, it strengthens the case for maintaining and expanding fluoridation programs.

The study “Early Childhood Exposures to Fluorides and Cognitive Neurodevelopment: A Population-Based Longitudinal Study” was published in the journal Research Reports: Clinical.