Urine metabolomics unravel the effects of short-term dietary interventions on oxidative stress & inflammation: a randomized controlled trial

Dietary biomarkers in urine are elusive in the context of diet induced oxidative stress & inflammation. Previously, we reported the effects of short-term (4-week) dietary interventions for Balanced Korean Diet (BKD) and Western diets including 2010 Dietary Guidelines for Americans (2010 DGA) and Typical American Diets (TAD) on various metabolic indices among the Korean adults with obesity. In particular, this research investigates the impact of these interventions on biomarkers related to oxidative stress and inflammation in both serum and concurrent urine metabolomes. Each dietary regimen was in silico and experimentally examined for their antioxidant levels. We assessed post-intervention variations in oxidative stress and inflammation biomarkers in serum, as well as the urine metabolite profiles for the participants ( n  = 48). Antioxidant contents and associated total antioxidant capacity (TAC) were significantly higher for the recommended diets (BKD and 2010 DGA) compared to TAD ( p  < 0.05). Butanol extracts from recommended diets (BKD and 2010 DGA) showed significantly higher antioxidant activity compared to TAD in ABTS (p < 0.01), DPPH, and FRAP (p < 0.05) assays. Consistent results were observed in total phenolic and flavonoid contents, mirroring their respective antioxidant activities. Following the intervention period, oxidative stress & inflammation markers in serum varied marginally, however, the urine metabolite profiles were clearly demarcated for the BKD and Western dietary groups (PC1 = 5.41%). For BKD group, the pre- and post-intervention urine metabolite profiles were clearly segregated (PLS2 = 2.93%). Compared to TAD, urine extracts from the recommended dietary group showed higher abundance of benzoic acid & phenolic derivatives (VIP > 0.7, p  < 0.05). Metabolites associated with oxidative stress were observed higher in the urine samples from western dietary groups compared to BKD. Urine metabolomics data delineated the post-intervention effects of three dietary interventions which corroborates the respective findings for their effects on metabolic indices.