Maternal iodine is vital for a growing fetus. It’s critical for normal development of the endocrine system, which includes glands such as the thyroid, ovaries, uterus, pancreas, prostate, and thymus. These tissues may not develop normally if the mother is iodine-deficient while pregnant.
The central nervous system is also dependent on adequate iodine sources for proper development. It has been well established that if a pregnant woman has low iodine intake, her baby can suffer from a wide variety of problems including having a low IQ. Animal studies have found the combination of fluoride exposure in utero and low iodine has greater negative effects on offspring learning and memory than either alone.
For a report that appeared in the journal Nutrients, researchers from the U.S. and Canada evaluated whether the maternal iodine levels modify the association between maternal fluoride intake and boys’ and girls’ IQ in 366 mother-child pairs. The children’s intelligence was assessed at three to four years, and the mother’s iodine intake was tested through urinary collections. The women’s fluoride intake was determined by looking at the amount of added fluoride in public water systems where the research subjects lived.
The authors found a significant association between IQ levels, low iodine, and fluoride intake in boys, but not girls. For boys whose mothers had low iodine, a 0.5 mg/g increase in fluoride concentration (a relatively small increase) was associated with a 4.65-point reduction in IQ.
For boys whose mothers had adequate iodine intake, a 0.5 mg/g increase in fluoride concentration was associated with a 2.95-point lower IQ.
The authors summarized: “These results suggest adequate iodine intake during pregnancy may minimize fluoride’s neurotoxicity in boys.”
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