Orange juice-derived flavanone and phenolic metabolites do not acutely affect cardiovascular risk biomarkers: a randomized, placebo-controlled, crossover trial in men at moderate risk of cardiovascular disease

Abstract

Background: Epidemiologic data suggest inverse associations between citrus flavanone intake and cardiovascular disease (CVD) risk. However, insufficient randomized controlled trial data limit our understanding of the mechanisms by which flavanones and their metabolites potentially reduce cardiovascular risk factors.

Objective: We examined the effects of orange juice or a dose-matched hesperidin supplement on plasma concentrations of established and novel flavanone metabolites and their effects on cardiovascular risk biomarkers in men at moderate CVD risk.

Design: In an acute, randomized, placebo-controlled crossover trial, 16 fasted participants (aged 51-69 y) received orange juice or a hesperidin supplement (both providing 320 mg hesperidin) or control (all matched for sugar and vitamin C content). At baseline and 5 h postintake, endothelial function (primary outcome), blood pressure, arterial stiffness, cardiac autonomic function, platelet activation, and NADPH oxidase gene expression and plasma flavanone metabolites were assessed. Before each intervention, a diet low in flavonoids, nitrate/nitrite, alcohol, and caffeine was followed, and a standardized low-flavonoid evening meal was consumed.

Results: Orange juice intake significantly elevated mean ± SEM plasma concentrations of 8 flavanone (1.75 ± 0.35 μmol/L, P < 0.0001) and 15 phenolic (13.27 ± 2.22 μmol/L, P < 0.0001) metabolites compared with control at 5 h postconsumption. Despite increased plasma flavanone and phenolic metabolite concentrations, cardiovascular risk biomarkers were unaltered. After hesperidin supplement intake, flavanone metabolites were not different from the control, suggesting altered absorption/metabolism compared with the orange juice matrix.

Conclusions: After single-dose flavanone intake within orange juice, circulating flavanone and phenolic metabolites collectively reached a concentration of 15.20 ± 2.15 μmol/L, but no effects were observed on cardiovascular risk biomarkers. Longer-duration randomized controlled trials are required to examine previous associations between higher flavanone intakes and improved cardiovascular health and to ascertain the relative importance of food matrix and flavanone-derived phenolic metabolites. This trial was registered at clinicaltrials.gov as NCT01530893.

Keywords: flavanones; flavonoids; phenolic metabolites; randomized controlled trial; vascular function.

Figures

FIGURE 1

Participant flowchart.

FIGURE 2

Mean ± SEM plasma concentrations of total flavanone metabolites (A) at baseline (i.e., 0 h) and 5 h after intervention in men at moderate cardiovascular disease risk [n = 16 (control), n = 14 (orange juice), and n = 15 (hesperidin supplement)]. Differences in study endpoints between interventions were analyzed by using a linear mixed model for crossover studies, with subjects nested within the intervention sequence as a random effect and experimental period, intervention sequence, baseline values, and intervention as fixed effects (intervention effect: P < 0.0001). Post hoc analysis with Tukey-Kramer adjustment was performed to determine which intervention was significantly different from control. ****P < 0.0001. Identified flavanone metabolites (B) and their proportions relative to total flavanone metabolite plasma concentrations at 5 h after the orange juice intervention: 1, hesperetin-glucuronide; 2, naringenin-7-glucuronide; 3, hesperetin-glucuronide; 4, hesperetin-diglucuronide; 5, hesperetin-diglucuronide; 6, naringenin-glucuronide; 7, hesperetin; and 8, naringenin.

FIGURE 3

Mean ± SEM plasma concentrations of total phenolic metabolites (A) at baseline (i.e., 0 h) and 5 h after the control (n = 16) and orange juice (n = 14) intervention in men at moderate cardiovascular disease risk. Differences in study endpoints between interventions were analyzed by using a linear mixed model for crossover studies, with subjects nested within intervention sequence as a random effect and experimental period, intervention sequence, baseline values, and intervention as fixed effects (intervention effect: ****P < 0.0001). Identified phenolic metabolites (B) and their proportions relative to total phenolic metabolite plasma concentrations at 5 h after the orange juice intervention: 1, hippuric acid; 2, dihydroferulic acid; 3, dihydroferulic acid–3-glucuronide; 4, 4-hydroxyphenylacetic acid; 5, vanillic acid; 6, hydroxyhippuric acid; 7, iso/ferulic acid–glucuronide; 8, 3-hydroxyhippuric acid; 9, isovanillic acid; 10, 3-hydroxyphenylacetic acid; 11, vanillic acid–glucuronide; 12, isovanillic acid–glucuronide; 13, iso/vanillic acid–glucuronide; 14, 4-hydroxy-benzoic acid; and 15, benzoic acid–4-glucuronide.