Background: Evidence suggests polyphenol-rich wild blueberry (WBB) consumption can improve cardiovascular health, but research in middle-aged and older adults with above-normal blood pressure (BP) is needed. Objective: Our study investigated the impact of 12 weeks of daily WBB consumption on vascular function (i.e., endothelial function, arterial stiffness), BP, blood biomarkers, and gut microbiota composition in adults with above-normal BP. Methods: In a randomized, double-blind, placebo-controlled, parallel-arm trial, postmenopausal women and men aged 40–75 y with elevated BP or stage-1 hypertension (HTN) (i.e., systolic BP 120–139 and/or diastolic BP (DBP) 80–89 mmHg) were randomized to consume either 22 g/d freeze-dried WBB powder or isocaloric placebo for 12 weeks. Endothelial function (primary outcome) was assessed using reactive hyperemia index (RHI) and Framingham RHI (fRHI). Secondary outcomes included arterial stiffness (carotid–femoral pulse wave velocity, augmentation index), brachial and aortic hemodynamics, cardiometabolic biomarkers, and gut microbiota composition. Outcomes were assessed at baseline and 12 weeks using linear mixed-effects models including treatment, time, and their interaction, with covariates retained via backward elimination. Alpha- and β-diversity, and differential abundance analyses assessed community structure and taxa associations. Results: Of 52 participants randomized, 44 completed the study (WBB = 24; placebo = 20; ~96% compliance/group). Participants were 57 ± 1.41 y, 34% female, and 64% with HTN. There were no main or interaction effects on RHI or fRHI. Aortic pulse pressure increased after 12 weeks of WBB consumption compared to placebo (+2.97 mmHg; 95% CI 0.29, 5.67). Within-group, placebo participants had increases in brachial DBP (+2.32 mmHg; 95% CI 0.16, 4.48), aortic DBP (+2.87 mmHg; 95% CI 0.39, 5.36), mean arterial pressure (MAP) (+2.61 mmHg; 95% CI 0.07, 5.15), AIx (+3.27%; 95% CI 0.15, 6.40), and AIx@75 (+4.68%; 95% CI 1.66, 7.70), but not in WBB group. AIx@75 at Week 12 was higher in placebo group compared to WBB (+4.99%; 95% CI 0.29, 9.69). β-diversity analyses showed main effect of treatment on overall community composition (PERMANOVA R 2 = 0.03, p = 0.048). Conclusions: Daily WBB consumption for 12 weeks did not improve vascular function, though data suggest it attenuated increases in DBP, MAP, and AIx indices, suggesting potential cardiovascular-protective effects and warranting further investigation.
Ghanem et al. (2026) studied this question.