Probiotics do not enhance anti-hypertensive effect of blueberry diets in hypertensive rats

Previously we showed that feeding polyphenol-rich wild blueberries (BB) to hypertensive rats lowered systolic blood pressure (BP). Since probiotic bacteria produce secondary metabolites from berry polyphenols which augment the health benefits of berry consumption, we hypothesized that adding probiotics to a BB-enriched diet would augment the anti-hypertensive effects of BB. Male spontaneously hypertensive rats were fed different AIN93G-based diets for 8 weeks (n=8 rats each diet): Control; 3% freeze-dried wild BB; 1% probiotic bacteria (PRO); or 3% BB + 1% PRO. BP was measured biweekly by the tail-cuff method, and urine was collected twice to determine markers of oxidative stress [F2-isoprostanes], nitric oxide synthesis [nitrites] and polyphenol metabolism [hippuric acid]. Systolic BP at week 8, but not sooner, was lower in the BB and PRO groups (163+5.9 mmHg and 168+6.2 mmHg, respectively) compared to the control diet (188+7.6 mmHg; p=0.04). Diet had main effects on diastolic BP at week 8 as well (p