Distinct Effects of Wheat and Black Bean Consumption on Postprandial Vascular Responses in People with Arterial Stiffness: A Pilot Randomized Cross-Over Study

Abstract

Background/Objective: Postprandial vascular responses impact vascular health. This study investigated whether eating pulses or whole grains can acutely relax blood vessels in people with arterial stiffness. Methods: A single-blinded, controlled randomized cross-over clinical trial was conducted to compare the effects of pulses (¾ cup black beans) versus whole grains (¾ cup whole wheat kernels, also known as wheat berries) versus white rice (¾ cup) on postprandial vascular responses in males and females with established arterial stiffness (n = 9, 3M/6F, 50-64 years old). Peripheral and central hemodynamic measurements were obtained non-invasively prior to and 2 h after food consumption and were compared by t-test within a food type. Results: Peripheral and central systolic blood pressure was increased (4%) after eating white rice but not after the consumption of wheat or beans. A marked decline in augmentation index at 75 bpm (arterial stiffness) from 26.1 ± 3.6% to 16.2 ± 2.0% was observed 2 h after eating whole wheat but not beans or white rice. All foods slightly decreased heart rate at 2 h but had limited effects on other parameters of circulatory or heart health. Conclusions: Eating whole wheat or beans acutely improved overall vascular and heart health when compared to white rice. The effects of wheat and beans were distinct, with whole wheat having a major positive effect on blood vessel stiffness. The findings suggest that regular inclusion of both whole wheat and beans in the diet would be beneficial for improving cardiovascular health in persons exhibiting signs of arterial dysfunction, thus providing a potential therapeutic benefit for individuals who are at risk of heart attack and stroke. The study was registered (NCT05818358) on ClinicalTrials.gov.

Keywords: augmentation index; black beans; blood pressure; postprandial response; pulse wave velocity; rice; wheat.

Figure 1

CONSORT diagram.

Figure 2

Augmentation index normalized to a heart rate of 75 beats/minute (AIx75) before (0 min) and after (120 min) consumption of wheat, beans, or rice. The asterisk (*) indicates a statistically significant (p < 0.05) change between 0 and 120 min within a food.

Figure 3

Principal Component Analysis. Abbreviations: delta AIx75, the change (T120 minus T0 min) in augmentation index normalized to a heart rate of 75 bpm.