Metabolomics profiles associated with an organic diet intervention in school children in Limassol, Cyprus: A cluster-randomized cross-over trial

Abstract

BACKGROUND AND AIM: Exposure to pesticides has been associated with oxidative stress in animals and humans. Previously, we showed that an organic food intervention reduced pesticide exposure and oxidative damage biomarkers over time, however associated metabolic changes are not fully understood yet. We assessed perturbations of the urine metabolome in response to an organic food intervention for children and its association with pesticides biomarkers [3-phenoxybenzoic acid (3-PBA) and 6-chloronicotinic acid (6-CN)]. We also evaluated the molecular signatures of metabolites associated with biomarkers of oxidative damage (OD) (8-iso-PGF2a and 8-OHdG) and related biological pathways. METHODS: We used data from the ORGANIKO LIFE+ trial (NCT02998203), a cluster-randomized cross-over trial conducted among primary school children in Cyprus. Participants (n=149) were asked to follow an organic food intervention for 40 days and their usual food habits for another 40 days, providing up to six first morning urine samples (850 samples in total). Untargeted GC-MS metabolomics analysis was performed. Metabolites with RSD≤20% and D-ratio≤50% were retained for analysis. Associations were examined using mixed-effect regression models and corrected for false-discovery rate of 0.05. Pathway analysis followed. RESULTS:Following strict quality checks, 156 features remained out of a total of 610. D-glucose was associated with the organic food intervention (β=-0.23, 95% CI: -0.37,-0.10), aminomalonic acid with the organic food intervention (β=-0.44, 95% CI:-0.68,-0.19) and the two OD biomarkers (β=-0.27, 95% CI:-0.34,-0.20 for 8-iso-PGF2a and β=0.19, 95% CI:0.11,0.28 for 8-OHdG) and uric acid with 8-OHdG (β=0.19, 95% CI:0.11,0.26). The most affected pathways were the starch and sucrose metabolism and pentose and glucuronate interconversions. CONCLUSIONS:Changes in the metabolomic profile of primary school children following a 40-day long systematic organic food intervention were observed. This is the first study providing evidence of differential expression of metabolites by an organic food intervention, corroborating the reduction in biomarkers of oxidative damage using metabolomics. KEYWORDS: organic food, metabolomics, pesticides, cluster randomized trial, oxidative stress, lipid damage