A study of
40 postmenopausal women with hypertension showed that after two months, those
who ate the equivalent of a cup of blueberries a day had lower blood pressure
(5% systolic and 6% diastolic). In the treated patients, nitric oxide was
increased, which might be the mechanism, since the latter is known to relax
arterial blood pressure.
See Johnson, SA at Florida State Univ, the lead author for
an article in the Journal of the Academy of Nutrition and Dietetics.