Just one cup of blueberries per day could be the key to reducing blood pressure and arterial stiffness, both of which are associated with cardiovascular disease.
The studies findings suggest that regular consumption of blueberries could potentially delay the progression of prehypertension to hypertension, therefore reducing cardiovascular disease risk.
The lead author Dr Johnson said she is interested in looking at how functional foods — foods that have a positive impact on health beyond basic nutrition — can prevent and reverse negative health outcomes, particularly for postmenopausal women.
Cardiovascular disease is the leading cause of death in the United States and elsewhere in the western world. Once women go through menopause, this puts them at an even greater risk for it. These findings suggest that the addition of a single food, blueberries, to the diet may mitigate the negative cardiovascular effects that often occur as a result of menopause.
Over an eight-week period, 48 postmenopausal women with pre- and stage-1 hypertension were randomly assigned to receive either 22 grams of freeze-dried blueberry powder — the equivalent to one cup of fresh blueberries — or 22 grams of a placebo powder. Participants, meanwhile, continued their normal diet and exercise routines.
At the beginning of the study, the team took participants’ blood pressure and measured their arterial stiffness and select blood biomarkers.
At the end of the eight weeks, participants receiving the blueberry powder on average had a 7 mmHg (5.1 percent) decrease in systolic blood pressure, which is the top number in the blood pressure reading that measures the pressure in the arteries when the heart beats. They also saw a 5 mmHg (6.3 percent) reduction in diastolic blood pressure, or the bottom number measuring the pressure in the arteries between heartbeats.
Additionally, participants in the blueberry-treated group had an average reduction of 97 cm/second (6.5 percent) in arterial stiffness.
They also found that nitric oxide, a blood biomarker known to be involved in the widening of blood vessels, increased by 68.5 percent. Helpful because arterial stiffness and the narrowing of blood vessels are both a part of hypertension. This rise in nitric oxide helps explain the reductions in blood pressure.
Previous studies on blueberries have shown positive effects on cardiovascular risk factors including blood pressure, but they all included large amounts of blueberry powder consumption, anywhere from 50 grams to 250 grams. In the case of 250 grams, that would translate to more than 11 cups of fresh blueberries, which may not be realistic for people to consume on a regular basis.
Multiple lifestyle factors and environmental and genetic confounders contribute to risk of cardiovascular disease, offering simple one food group suggestions may appear attractive, but should not be seen as an alternative to the aggregated benefits of multiple contiguous changes.
 Johnson SA, Figueroa A, Navaei N, Wong A, Kalfon R, Ormsbee LT, Feresin RG, Elam ML, Hooshmand S, Payton ME, Arjmandi BH. Daily Blueberry Consumption Improves Blood Pressure and Arterial Stiffness in Postmenopausal Women with Pre- and Stage 1-Hypertension: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial. J Acad Nutr Diet. 2015 Jan 2. View Abstract