A 2026 Canadian study of 485 mother-child pairs links prenatal fluoride exposure from maternal tea consumption to lower childhood IQ scores at age three to four. Each 0.5 mg/day increase in estimated fluoride intake from tea, roughly one cup of black tea, is associated with a 2.24-point lower full-scale IQ score. While tea plants naturally accumulate fluoride, researchers note the observational study cannot establish causality and suggest clearer product labeling to help pregnant individuals.
Prenatal fluoride exposure effects
- ▪Each 0.5 milligram per day increment in estimated prenatal fluoride intake from tea was associated with a 2.24-point lower childhood full-scale intelligence quotient score.
- ▪A 2026 study linked higher estimated prenatal fluoride exposure from maternal tea intake during pregnancy to lower childhood full-scale intelligence quotient scores at age three to four.
Tea fluoride content
- ▪Tea consumption can account for up to 48 percent of total fluoride exposure in adults.
- ▪Tea plants act as bioaccumulators, leading to relatively high fluoride concentrations in some teas, particularly brick and black teas.
Canadian birth cohort methodology
- ▪The study assessed maternal beverage consumption using questionnaires and measured maternal urinary fluoride levels from spot urine samples collected during pregnancy.
- ▪Researchers analyzed 485 mother-child pairs from the Canadian Maternal-Infant Research on Environmental Chemicals cohort to evaluate prenatal fluoride exposure and child intelligence.
- ▪Children's intellectual abilities were assessed at an average age of 3.4 years using the Wechsler Preschool and Primary Scale of Intelligence-III.
Study limitations
- ▪The observational study cannot establish causality because beverage intake was self-reported and fluoride concentrations in participants' actual tea were not measured.
- ▪The study's generalizability is limited by its predominantly White, highly educated cohort and restriction to public tap-water consumers.
Product labeling recommendations
- ▪Researchers suggested pregnant individuals consider limiting tea consumption, though the study did not establish a safe or harmful number of cups.
- ▪The study findings underscore the need to monitor fluoride levels in tea and increase transparency through clearer product labeling.
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