Fluoride is commonly found in our environment, mainly in drinking water, food, beverages, and dental products. It is promoted for its benefits to dental and oral health.
A 2006 report by the National Research Council (NRC) suggested that high levels of naturally occurring fluoride in drinking water might harm the brain, prompting calls for more research. Since then, more studies, including some from North America, have explored the effects of fluoride on brain function, particularly during pregnancy.
In 2016, the National Toxicology Program (NTP) reviewed animal studies on fluoride’s impact on learning and memory. The review found moderate evidence that fluoride exposure can impair animal learning and memory.
A new study at the National Institute of Environmental Health Studies at the National Institutes of Health, conducted a systematic review of the human, experimental animal, and mechanistic literature to evaluate the extent and quality of the evidence linking fluoride exposure to neurodevelopmental and cognitive effects in humans.
The study found that higher fluoride exposure consistently correlates with lower IQ scores.
The research reviews 74 other studies exploring how the mineral may affect children’s IQ levels. Of the 74 studies, 22 were rated high quality, and 52 were rated low quality. Studies were conducted in 10 countries, including Canada, China, Denmark, India, Iran, Mexico, Pakistan, New Zealand, Spain, and Taiwan.
These studies measured fluoride in drinking water or urine. Measuring fluoride in urine estimates total fluoride exposure.
The meta-analysis found a significant link between higher fluoride exposure and lower IQ scores in children. For every 1 mg/L increase in urinary fluoride, children’s IQ dropped by 1.63 points.
The analysis also found that, based on high-quality studies, fluoride exposure was linked to lower IQ levels below 1.5 mg/L in urine or drinking water. However, fewer studies were conducted on fluoride in drinking water, leading to some uncertainty about the effects at levels below 1.5 mg/L. There was insufficient data to determine if 0.7 mg/L of fluoride in drinking water affected children’s IQ.
Authors noted, “An association indicates a connection between fluoride and lower IQ; it does not prove a cause and effect. Many substances are healthy and beneficial when taken in small doses but may cause harm at high doses. More research is needed to understand better if there are health risks associated with low fluoride exposures.”
Journal Reference:
- Kyla W. Taylor, Sorina E. Eftim, Christopher A. Sibrizzi et al. Fluoride Exposure and Children’s IQ Scores: A Systematic Review and Meta-analysis. JAMA Pediatrics. DOI: 10.1001/jamapediatrics.2024.5542
