Prenatal exposure to environmental contaminants, including potentially toxic metals (PTMs), is a constant public health concern. The telomere length (TL) and mitochondrial DNA (mtDNA) content are sensitive biomarkers of biological aging and mitochondrial function that could be altered by exposure to pollutants. The Mexico City Metropolitan Area (MCMA) is characterized by being a densely populated and polluted urban region. This study aimed to evaluate the association between prenatal exposure to mixtures of PTMs and essential elements with mtDNA content and TL in newborns from the MCMA, and to explore the influence of genetic variants rs2736100 and rs2736098 on TL. For quantifying prenatal exposure to 24 elements in 160 umbilical cord blood samples, we used ICP-MS, TL and mtDNA content were determined by qPCR, and variant genotyping was performed using TaqMan probes. Associations were estimated using linear regression and two-index Weighted Quantile Sum (WQS) regression, a method that estimates the effects of chemical mixtures on a health outcome in the same model through the inclusion of two indices (evaluating both positive and negative directions simultaneously). Concentrations of several essential and toxic elements were associated with both TL and mtDNA content. The direction and magnitude of these effects varied according to the predominant metals in each WQS-identified mixture. The most influential metals were arsenic, antimony, titanium, manganese, and zinc. Finally, under an allelic model, the TERT variants showed a suggestive modulatory effect on TL lengthening. In summary, our findings suggest that prenatal exposure to metal mixtures may influence molecular aging markers at birth, potentially increasing disease susceptibility later in life.

Background/Objectives: Human milk contains hormonal and immune bioactives that may vary with maternal, infant and perinatal characteristics including maternal body mass index (BMI), infant sex and birth mode. However, evidence linking these factors remains inconsistent. This exploratory study evaluated if maternal, infant and perinatal characteristics were associated with milk composition. Secondarily, hypothesis-generating analyses examined if milk hormones and cytokines were associated with infant anthropometric Z-scores. Methods: This cross-sectional study included 47 healthy term, exclusively breastfed mother–infant dyads with ages ranging from 0.39 to 6.01 months. Milk hormones (ghrelin, leptin, insulin and glucagon) and cytokines (IL-1β, IL-2, IL-4, IL-6, IL-7, MCP-1, IFN-γ and TNF-α) were quantified using multiplex assays and infant anthropometry was evaluated using WHO Z-scores. Adjusted models included infant age, postpartum maternal BMI, infant sex, and birth mode. Analyte-specific complete-case samples ranged from 37 to 44. All p values were nominal, and false-discovery-rate-adjusted q values assessed multiplicity. Results: Postpartum maternal BMI was positively associated with milk leptin (β = 0.152; p < 0.001; n = 39) and cesarean delivery, relative to vaginal delivery, was associated with lower milk glucagon (β = −0.579; p < 0.001; n = 37). Milk IFN-γ showed nominal exploratory positive associations with weight-for-length Z-score (β = 0.188; p = 0.017; n = 39) and BMI-for-age Z-score (β = 0.211; p = 0.032; n = 39). Conclusions: Postpartum maternal BMI and birth mode showed robust adjusted associations with leptin and glucagon, respectively. The cross-sectional design does not establish temporal direction or clinical relevance. The IFN-γ findings require longitudinal evaluation.

Introducción: El sistema inmune es una red compuesta por varias células y moléculas que responden de manera conjunta contra antígenos exógenos y endógenos. Actualmente, las enfermedades infecciosas siguen siendo una problemática de salud pública, afectando principalmente a la población inmunológicamente vulnerable que incluye a los infantes, por lo que se destaca la importancia de buscar el fortalecimiento del sistema inmune mediante una alimentación adecuada. El objetivo de este trabajo es hacer una revisión de alimentos con potencial inmunomodulador, describiendo sus nutrientes y compuestos bioactivos, y presentar ejemplos de alimentos que los contienen, demostrando la importancia de su implementación en la dieta a una edad temprana. Resultados: Se describió la función de diversos nutrientes, vitaminas y minerales, omega 3 y glutamina, así como de compuestos fenólicos en el sistema inmune. También se destacó el rol de los probióticos sobre la inmunidad intestinal, relacionando a la microbiota como un componente esencial en el sistema inmune. Se presentaron alimentos como la cebolla, el ajo, la manzana, la papaya, entre otras frutas y verduras comunes en el país. Conclusiones: Los micronutrientes y compuestos bioactivos tienen la capacidad de modular el sistema inmunológico. Una nutrición adecuada es esencial para el desarrollo correcto del sistema inmune y es fundamental en la infancia, quienes poseen un sistema en desarrollo.