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At the 2024 Journées Francophones de la Nutrition held in Strasbourg, from December 4 to 6, global experts gathered to discuss the pressing issue of contaminants and their effects on thyroid function, focusing particularly on the impact of maternal thyroid hormones on fetal brain development. The question of whether iodine supplementation should be routine during pregnancy also emerged as a central topic.
The Importance of Maternal Thyroid Hormones
Jean-Baptiste Fini, PhD, a biologist at the French National Centre for Scientific Research, stressed the vital role of maternal thyroid hormones in fetal brain maturation. Although severe iodine deficiency, which once caused cretinism, is rare in France today, even mild deficiencies can have lasting effects on fetal development. Fini pointed to studies demonstrating that children born to mothers with low thyroid hormone levels (hypothyroxinemia) during pregnancy exhibited lower IQ scores, reduced gray matter density, and smaller cortical volumes.
The Threat of Contaminants
Beyond iodine levels, fetal thyroid metabolism can be disrupted by contaminants that pass through the placental barrier. Studies presented at the conference explored the dangers posed by these contaminants, especially those transmitted through the mother’s diet. One significant epidemiological study revealed that exposure to certain chemicals in utero was linked to language delays in 30-month-old children. Experimental studies in tadpoles also demonstrated how these chemicals interfered with genes responsible for neural stem cell activity.
Can Iodine Mitigate Contaminant Damage?
Bernard Salles, DVM, PhD, a toxicologist at the French National Research Institute for Agriculture, Food, and Environment, highlighted that many European women consume iodine levels below the World Health Organization’s recommended intake. Furthermore, over 90% of women of childbearing age are exposed to thyroid-disrupting chemicals. Salles emphasized findings from experiments with tadpoles that revealed iodine supplementation could correct thyroid dysfunction caused by a combination of thyroid-disrupting contaminants.
If similar effects are confirmed in mammals, including humans, it could lead to the recommendation of routine urinary iodine testing for pregnant women during early pregnancy. The presence of harmful substances in the diet, alongside iodine deficiency, could necessitate a reevaluation of public health guidelines to ensure the best possible outcomes for fetal development.
Improving Regulatory Measures
The French National Institute of Health and Medical Research (INSERM) recently published a report on the health effects of pesticide exposure. The 2021 findings, which were more comprehensive than the 2011 report, highlighted a correlation between pesticide exposure and thyroid disorders. While definitive causal links have not been established, certain chemicals, such as organochlorine insecticides, herbicides, and organophosphorus pesticides, were identified as potential disruptors of thyroid function, particularly in individuals with high exposure.
Salles criticized the current European pesticide regulations for being outdated and based on questionable methodologies, primarily relying on rodent models. He argued that amphibians offer a more accurate model for studying the effects of contaminants on human thyroid function. Despite these challenges, there have been some positive changes, including the introduction of QR codes on product labels to provide consumers with more information about toxicity.
The Need for Further Research and Action
The discussion at the Journées Francophones de la Nutrition underscored the need for more experimental toxicology studies to confirm the links between contaminants and thyroid disruption in humans. Experts are calling for improved regulatory frameworks, including more precise testing methods and better transparency in labeling, to protect the health of pregnant women and their babies.
Disclaimer:
The findings and recommendations discussed in this article are based on the latest scientific research. However, as with all medical matters, pregnant women should consult with their healthcare providers before making any decisions regarding iodine supplementation or other interventions. Further research is needed to confirm the long-term effects of iodine supplementation and contaminants on fetal health.
