Egg Introduction during Infancy is Associated with Lower Fat Mass Index in Females at Early Adolescence

Background: Egg consumption may play an important role in early-life growth given their high-quality protein, essential fatty acids, and micronutrients. Objectives: Study objectives were to examine the longitudinal associations of infant age at egg introduction with obesity outcomes in early childhood, middle childhood (mid-childhood), and early adolescence. Methods: We used existing data from 1089 mother-child dyads from Project Viva to estimate age at egg introduction through a questionnaire completed by mothers at ∼1 y postpartum (mean ± SD, 13.3 ± 1.2 mo). Outcome measures included height and weight (early childhood, mid-childhood, and early adolescence), body composition including total fat mass, trunk fat mass, and lean mass (mid-childhood and early adolescence), and plasma adiponectin and leptin (early and mid-childhood and early adolescence). We defined childhood obesity as sex- and age-specific BMI ≥ 95th percentile. We estimated the associations of infant age at egg introduction with risk of obesity using multivariable logistic regression and multivariable linear regression models for BMI-z-score, body composition measures, and adiposity hormones; adjusted for maternal prepregnancy BMI and sociodemographics. Results: Among females, those introduced to egg by the 1-y survey had a lower total fat mass index (confounder-adjusted mean difference, −1.23 kg/m²; 95% CI: −2.14, −0.31), and trunk fat mass index (confounder-adjusted mean difference, −0.57 kg/m²; 95% CI: −1.01, −0.12) in early adolescence compared to those not introduced (reference group). However, no associations between infant age at egg introduction and risk of obesity were observed among males (confounder-adjusted odd ratio [aOR], 1.97; 95% CI: 0.90, 4.30) or females (aOR, 0.68; 95% CI: 0.38, 1.24) across all ages. Egg introduction in infancy was associated with lower plasma adiponectin among females (confounder-adjusted mean difference, −1.93 μg/mL; 95% CI: −3.70, −0.16) in early childhood only. Conclusions: Egg introduction during infancy among females is associated with lower total fat mass index in early adolescence and plasma adiponectin in early childhood. This trial was registered at clinicaltrials.gov as NCT02820402.