Orange juice and hesperidin increase flavanone exposure without detectable short-term vascular benefits: a randomized...

Orange juice is a major dietary source of hesperidin, a citrus flavanone with vascular protective effects in experimental models. However, whether nutritionally realistic intake levels induce measurable benefits in humans remains unclear. We investigated the effects of orange juice and hesperidin supplementation, at realistic dietary doses, on vascular function, flavanone bioavailability, and molecular responses. Thirty-seven centrally overweight men completed a randomized, double-blind, controlled, three-period crossover trial with three 6-week interventions separated by washout periods. Participants consumed daily 330 mL of 100% orange juice (OJ), an isoenergetic control beverage (CON), or a hesperidin-enriched control beverage (HESP, 210 mg day^-1). Fasting vascular, metabolic and anthropometric parameters were assessed before and after each intervention, with flow-mediated dilation (FMD) as the primary endpoint. Postprandial FMD, circulating flavanone metabolites and oxylipin profiles were evaluated following a standardized high-fat meal challenge, and flavanone bioavailability was assessed by 24 h urinary excretion. Whole-blood transcriptomics were performed in a subset (n = 9). Plasma exposure to phase II hesperetin metabolites (AUC_{0-6 h}) and 24 h urinary excretion were comparable after OJ and HESP, indicating effective hesperidin delivery and limited matrix effects on bioavailability. Neither intervention significantly affected fasting or postprandial FMD, vascular, metabolic or anthropometric parameters, or oxylipin profiles versus CON. Marked interindividual variability was observed in vascular responses and flavanone bioavailability, although treatment effects were unrelated to baseline endothelial function or flavanone exposure. Exploratory transcriptomic analyses suggested modulation of pathways involved in vascular biology following OJ and HESP. Under nutritionally realistic conditions, orange juice and hesperidin induced measurable biological engagement without detectable short-term vascular benefits, highlighting the complexity of linking flavanone exposure to functional vascular outcomes in humans.