Flavanones protect from arterial stiffness in postmenopausal women consuming grapefruit juice for 6 mo: a randomized, controlled, crossover trial.

Randomized, double-blind, controlled crossover trial in healthy, nonsmoking postmenopausal women in France, aged 50-65 years. Fifty-two women were randomized to treatment sequences including grapefruit juice and a control beverage; 4 were lost to follow-up during the first 6-month period, and baseline characteristics were reported for 48 women.

Participants consumed 340 mL/day of blond grapefruit juice orally for 6 months per crossover period, providing about 210 mg/day naringenin glycosides (105 mg naringenin aglycone). The comparator was a flavanone-free control beverage.

Grapefruit juice reduced central arterial stiffness compared with the control beverage, suggesting a vasculoprotective effect. Carotid-femoral pulse wave velocity was lower with grapefruit juice than with control (7.36 6 1.15 m/s vs 7.70 6 1.36 m/s; P = 0.019). In contrast, endothelial function did not improve: FMD was 3.97 6 2.37% with grapefruit juice versus 4.32 6 2.54% with control (P = 0.739), and PAT ratio was 2.5 6 0.59 versus 2.6 6 0.48 (P = 0.208). Blood pressure, glucose-insulin markers, hs-CRP, IL-6, and ORAC also showed no significant between-condition differences.

The study was small and restricted to healthy Caucasian postmenopausal women, which limits generalizability. Four participants were lost to follow-up during the first intervention period, and multiple secondary vascular, metabolic, and inflammatory outcomes were null. Adverse events were not reported, and grapefruit has potential drug-interaction concerns that may affect applicability.