Effects of Concord grape juice on ambulatory blood pressure in prehypertension and stage 1 hypertension.

Background Consumption of flavonoid-containing foods may be useful for the management of hypertension Objective We investigated whether 100% Concord grape juice lowers blood pressure in patients with prehypertension and stage 1 hypertension Design We conducted a double blind crossover study to compare the effects of grape juice (7 mL kg(-1) d(-1)) and matched placebo beverage on 24-h ambulatory blood pressure stress-induced changes in blood pressure, and biochemical profile Participants consumed each beverage for 8 wk with a 4-wk rest period between beverages They ceased consumption of grapes and other flavonoid containing beverages throughout the study Results We enrolled 64 otherwise healthy patients taking no anti hypertensive medications (31% women 42% black age 43 +/- 12 y) Baseline mean (+/- SD) cuff blood pressure was 138 +/- 7 (systolic)/82 +/- 7 (diastolic) mm Hg No effects on the primary endpoint of 24-h mean systolic blood pressure diastolic blood pressure or stress induced changes in blood pressure were observed A secondary endpoint was nocturnal dip in systolic pressure At baseline nocturnal pressure was 8 3 +/- 7 1% lower at night than during daytime The mean nocturnal dip increased 1 4 percentage points after grape juice and decreased 2 3 percentage points after placebo (P = 0 005) Fasting blood glucose was 91 +/- 10 mg/dL at baseline for the entire cohort Glucose decreased 2 mg/dL after consumption of grape juice and increased 1 mg/dL after consuming the placebo (P = 0 03) Conclusions We observed no effect of grape juice on ambulatory blood pressure in this cohort of relatively healthy individuals with modestly elevated blood pressure Secondary analyses suggested favorable effects on nocturnal dip and glucose homeostasis that may merit further investigation This trial was registered at clinical trials gov as NCT00302809 Am J Clin Nutr 2010 92 1052-9