Solvik BS, Øyen J, Kvestad I, et al. - Data from a 2-armed RCT, the Fish Intervention Studies-KIDS (FINS-KIDS), were analyzed to examine the impacts of fatty fish intake compared with meat intake on various biomarkers [ie, omega-3 (n–3) PUFAs, urinary iodine concentration (UIC), 1-methylhistidine (1-MH), and trimethylamine N-oxide] in preschool children. Two hundred thirty-two children were individually randomly assigned in a 1:1 ratio to either the intervention (fish group) or control (meat group), stratified by gender. According to this exploratory analysis, among the 86 biomarkers studied, fatty fish consumption had the greatest impact on n–3 PUFAs, UIC, hair mercury, and plasma 1-MH. Biomarkers linked to micronutrient status, inflammation, essential amino acid, choline oxidation, and tryptophan pathways showed no or minimal effects.