References
Urine sampling and intake of beetroot juice and placebo in the three experimental sessions.From the bottom to the top, Boxplot of 4-methylpyridine-2-carboxylic acid and dopamine-3-O-sulfate for all the individuals across the sampling time for experimental session A. Statistical significance was assessed by two-way ANOVA—all pairwise multiple comparison procedures (Bonferroni Boxplot of 4-methylpyridine-2-carboxylic acid and dopamine-3-O-sulfate for all the individuals across the sampling time for experimental session B. Statistical significance was assessed by two-way ANOVA—all pairwise multiple comparison procedures (Bonferroni Boxplot of 4-methylpyridine-2-carboxylic acid and dopamine-3-O-sulfate at T1, T2, T3, and T4 for days A (blue) and B (red). Red asterisk indicates a statistically significant difference, according to paired Student’s PLS-DA performed between subjects at day A (blue) and day B (red): Boxplot of urinary biomarkers related to physical activity. A (blue) indicates experimental session at rest, B (red) indicating experimental session with physical activity, being equal the RBJ intake.PLS-DA performed between subjects on day B (red) and day C (green): Boxplot of urinary biomarkers related to red beetroot juice intake. B (red) indicates RBJ intake, C (green) indicates placebo intake, being equal the physical activity.Possible metabolic fate of betanin in the stomach.Physiologic model of intestinal absorption for dopamine, betanin, and 4-methylpyridine-2-carboxylic acid.Mean and standard deviation (SD) of red beetroot juice metabolites expressed as mg/100 mL of juice, measured by nuclear magnetic resonance spectroscopy on the final product.Resonance assignment of 4MP2CA and DA3S: s—singlet; d—doublet; t—triplet; dd—doublet of doublets. Bold indicated the resonances that have been taken into account for quantitation.