LITERATURE REVIEW

1) Ultraprocessed Food and Behavior - Among 2077 participants, 1092 (52.6%) were male; 1376 children (66.2%) were White, 480 children (23.1%) were multiracial, and 221 children (10.7%) were identified as another ethnic group. At age 3 years, UPF contributed a mean (SD) of 45.5% (11.6%) of total energy intake. At age 5 years, the mean (SD) CBCL scores were 44.6 (9.1) for internalizing, 39.6 (9.4) for externalizing, and 41.2 (9.0) for total behavior. Each 10% increase in energy from UPF was associated with higher CBCL internalizing, externalizing, and total scores. Substitution of 10% energy from UPF with (Minimally) MPF was associated with lower internalizing, externalizing, and total scores. Conclusions and Relevance  In this cohort study of preschoolers in Canada, higher UPF intake was associated with adverse behavioral and emotional symptoms by age 5 years. These findings suggest that replacing UPF with MPF during the preschool years may support healthier behavioral development, with potential benefits for long-term mental health. These findings also support ongoing policy actions that promote MPF and underscore the need for early-life dietary interventions. (Kavangh et. al. 2026)

Straightforward issue - Schools are the largest source of UPF for our kids - UGH!!!!

2) Immune Heavy but important: "Mucosal-associated invariant T (MAIT) cells are predominantly located in barrier tissues where they rapidly respond to pathogens and commensals by recognizing microbial derivatives of riboflavin synthesis. Early-life exposure to these metabolites imprints the abundance of MAIT cells within tissues, so we hypothesized that antibiotic use during this period may abrogate their development. We identified antibiotics that deplete riboflavin-synthesizing commensals and revealed an early period of susceptibility during which antibiotic administration impaired MAIT cell development. The reduction in MAIT cell abundance rendered mice more susceptible to pneumonia, while MAIT cell–deficient mice were unaffected by early-life antibiotics. Concomitant administration of a riboflavin-synthesizing commensal during antibiotic treatment was sufficient to restore MAIT cell development and immunity. Our work demonstrates that transient depletion of riboflavin-synthesizing commensals in early life can adversely affect responses to subsequent infections." (LeBlanc et. al. 2026)

Take Home: Early exposure to antibiotics can reduce the number of healthy commensal gut bacteria that play an important role to support immune system development. In this animal model, administering probiotics to replace lost healthy gut bacteria during antibiotic treatment can preserve long-term immunity protecting against adult respiratory diseases such as pneumonia. Thus, early antibiotic exposure is now associated with atopic diseases, infectious susceptibility, immune dysregulation, neurobehavioral issues and on and on. Mechanisms continue to be immuno-metabalo-microbial in systems origin. Avoiding (when possible) antibiotics in early life is critical to normal tolerance and immune development. It is increasingly difficult to view the microbiome merely as a collection of organisms. Papers like this support the concept that the microbiome acts more like a developmental signaling organ, delivering information that shapes how the immune system is built.

Kavanagh JAMA

LeBlanc J Exp Med