A study published in the journal Nutrients, led by IDIAPJGol researcher Esther Cendra and Rovira i Virgili University researcher Nerea Becerra, concludes that following a low-quality plant-based diet during pregnancy—characterized by high consumption of sugary drinks, refined grains, and other processed foods—is associated with an increased risk of externalizing behavioral problems in children, such as attention deficit hyperactivity disorder (ADHD) and oppositional defiant behavior. In contrast, following a healthy plant-based diet rich in fruits, vegetables, and legumes has a neutral effect. These findings highlight the importance of distinguishing between healthy and unhealthy plant-based foods when evaluating diets during pregnancy.

As for the results, the study—based on a sample of 201 mother-child pairs from the ECLIPSES cohort, a project led by Professor Victoria Arija in the Camp de Tarragona region—found that greater adherence to an unhealthy plant-based diet during pregnancy correlated with a higher likelihood of problematic behaviors such as aggression, ADHD, and oppositional defiant disorder. These effects were especially pronounced in girls. Conversely, the healthy plant-based diet showed no statistically significant association with any of the analyzed child behavior parameters.

The results were obtained from food frequency questionnaires administered to the pregnant participants, which allowed researchers to calculate two diet quality indexes depending on whether the predominant plant-based foods were healthy or unhealthy. Child behavior was assessed using the international Child Behavior Checklist questionnaire. The data were adjusted for multiple variables, such as maternal age, prenatal anxiety, the child’s diet quality, and other obstetric and sociodemographic factors.

This study is based on the premise that maternal diet plays a crucial role in fetal brain development. It aligns with other studies that conclude that a diet high in sugars and processed foods during pregnancy may promote processes like oxidative stress, inflammation, and hormonal imbalances that negatively affect neurodevelopment. Other research also suggests these effects may have an epigenetic basis and differ between sexes. This could explain why girls are more sensitive to maternal dietary changes during pregnancy.

Article reference:
Cendra-Duarte E, Becerra-Tomás N, Canals J, Jardí C, Arija V. Association of Prenatal Healthy and Unhealthy Plant-Based Diets with Behavioral Outcomes in Preschool Children. Nutrients. 2025 Apr 18;17(8):1372. doi: 10.3390/nu17081372. PMID: 40284235; PMCID: PMC12030138.