Darker‐Coloured Beans Induce Acute Vasorelaxation In Healthy Adults

Abstract

Consumption of pulses (dried beans, peas, chickpeas, lentils) over many weeks can decrease cardiovascular disease risk. However, it is unknown whether pulses can affect blood vessels characteristics within a few hours of consumption. We hypothesized that dried beans would yield greater improvements in vascular tone (an indication of endothelial responsiveness to blood flow) compared to a rice control. We therefore compared different bean varieties (black, navy, pinto, red kidney) and white rice for their acute effects on blood pressure and vascular tone in healthy individuals. Vascular measurements were obtained in 8 healthy adults (4 men/4 women; 37±4 years; body mass index of 24.3±0.9 kg/m2) before and at 2 and 6 hours after eating ¾ cup of beans or rice. The study was designed as a crossover with minimum 1 week between consumption of the test articles. Systolic blood pressure was reduced within 2 hours following consumption of red kidney beans compared to rice control (111±5 vs 118±6 mmHg, p<0.05). Blood pressure was not affected by the other beans. There was greater vasorelaxation, as shown by a reduced pulse wave reflection magnitude, 6 hours following consumption of red kidney beans and black beans compared to navy and pinto beans (53.3±3.3% and 53.4±4.4% vs 61.1±3.4% and 64.3±3.4%, respectively; p<0.05). Additionally, reflection magnitude following consumption of red kidney beans was significantly reduced at 6 hours compared to 2 hours post consumption (53.3±3.3% vs 61.1±3.7%, p<0.05). Reflection magnitude did not change between baseline and 2 hours. Arterial stiffness parameters were also measured. Black beans showed reduced augmentation pressure after 6 hours compared to rice (3.8±0.8 vs 6.9±1.5 mmHg, p<0.05); black beans, red kidney beans, and pinto beans had lower pulse wave velocity compared to navy beans after 2 hours (5.9±0.4, 5.8±0.4, and 5.8±0.3 vs 6.1±0.2 m/s, respectively; p<0.05), and black beans had lower pulse wave velocity compared to pinto beans after 6 hours (5.5±0.4 vs 6.3±0.2 m/s, p<0.05). These results suggest seed coat pigment may be a factor in functionality among the different bean types. Overall, darker‐coloured beans elicited a positive effect on the tensile properties of blood vessels, and this acute response may provide insight for how pulses modify vascular function.Support or Funding InformationJLC is funded by the Canadian Institutes of Health Research, and funding for this research project was provided by Manitoba Pulse and Soybean Growers.