Exploring Sr and Ba elemental signatures through time resolved histology-driven biogeochemistry in exfoliated deciduous teeth from contemporary children with diverse dietary habits

Deciduous tooth enamel carries chemical signatures of maternal diet during pregnancy and of an infant’s diet during early postnatal life. Therefore,a thorough understanding of the elemental signature, particularly of strontium (Sr) and barium (Ba), is critical to understanding the trophic level of the mother-infant dyad. This study examines N=27 exfoliated deciduous teeth from contemporary individuals that were either breastfed by mothers that consumed a plant-based diet (N=8), or by mothers that consumed an omnivorous diet (N=19). All teeth were sectioned following standard dental histology procedures and Sr and Ba concentrations were measured along the enamel-dentine junction using spatially resolved laser-based histology-driven mass spectrometry (LA-ICPMS). Results show no significant difference in Sr and Ba concentrations in the prenatal enamel between the two dietary groups, suggesting that the mother's gut effectively discriminates trace elements, regardless of her diet. Infants exclusively breastfed by omnivorous mothers have lower postnatal Sr (mean = 85.03±71 ppm) concentrations compared to infants exclusively breastfed by mothers with a plant-based diet (Sr mean=134.10±119 ppm). Infants fed exclusively with formula milk have the highest mean post-natal Sr concentrations (Sr mean=208.5±92 ppm). As a general pattern, mothers on a plant-based diet during pregnancy show reduced variability in both Sr and Ba concentrations as measured in theprenatal enamel of their offspring. This study shows that it is possible to discriminate differences in maternal diet through her offspring's deciduous dental enamel, which opens a new window into the study of the mother-infant dyad trophic levels in past human individuals.