Daily consumption of about 1 cup of fresh blueberries may help reduce arterial stiffness and decrease blood pressure (BP) by improving vasodilation due to the increased production or bioavailability of nitric oxide (NO), said Sarah A. Johnson, PhD, RD, CSO, Florida State University, Tallahassee, Florida, USA.

Hypertension (HTN) is a modifiable risk factor for cardiovascular disease (CVD) [Go AS et al. Circulation 2013; Rosamond W et al. Circulation 2008]. HTN currently affects >77 million Americans [Go AS et al. Circulation 2013]. Postmenopausal women seem to be affected disproportionately. [Barton M, Meyer MR. Hypertension 2009; Rosenthal T, Oparil S. J Hum Hypertens 2000]. The causes of HTN are multifactorial but are partly due to endothelial dysfunction, which results in decreased vasodilation and increased vasoconstriction. Endothelial dysfunction also increases stiffness of arteries, which is involved in the development and progression of both HTN and CVD [Wallace SML et al. Hypertension 2007; Bonetti PO et al. Arterioscler Thromb Vase Biol 2003; Taddei S et al. Curr Pharm Dis 2003; Widlansky ME et al. J Am Coll Cardiol 2003; Koh KK et al. J Am Coll Cardiol 2001].

The treatment of BP in prehypertensive individuals and those with stage 1 HTN focuses on lifestyle modifications (eg, diet) [Chobanian AV. Hypertension 2003]. The polyphenol constituents of berries, including blueberries, appear to be beneficial in reducing cardiovascular risk, as judged from their effects on BP, endothelial function, and arterial stiffness [Rodriguez-Mateos A et al. J Agric Food Chem 2013; Basu A et al. Nutr Rev 2010]. However, the influence of blueberries on arterial stiffness measured by pulsed wave velocity (PWV) had not previously been studied.

Dr. Johnson and colleagues hypothesized that eating 22 g of freeze-dried blueberry powder daily for 8 weeks would reduce arterial stiffening and improve endothelial function, in turn reducing BP. The double-blind placebo-controlled trial comprised 48 postmenopausal women with pre-HTN or stage 1 HTN. They were randomly assigned to receive the daily blueberry powder (n = 20) or the same daily quantity of placebo powder (n = 20). Brachial BP and brachial-ankle and carotid-femoral pulsed wave velocity were measured at baseline, 4 weeks, and 8 weeks. Plasma levels of NO were measured at the same times.

Daily consumption of blueberry powder for 8 weeks significantly reduced systolic and diastolic BP (Table 1) and brachial-ankle PWV (Table 2). Also, NO production was significantly elevated at 8 weeks in those whose daily diet included the blueberry powder (Table 3).

While noting that these results need to confirmed in a larger study, the researchers concluded that blueberry ingestion may result in increased NO production by endothelial cells, which may directly result in vasodilation and reductions in BP. Moving forward, further study is needed to assess the influence of dose on BP response and the effects of blueberry powder over more prolonged periods and in other populations.