Processing method modulates the effectiveness of black beans for lowering blood cholesterol in spontaneously hypertensive rats.

BACKGROUND: Various foods are known to have beneficial effects on health when consumed whole; however, there is a trend towards preparing foods from processed ingredients, and it remains unclear whether the benefits of the whole food are retained. The purpose of this study was therefore to examine whether different processing techniques affect the lowering of cholesterol and the vascular effects of black beans (Phaseolus vulgaris L.). RESULTS: Beans were prepared by overnight soaking and boiling - the standard method - and by micronization, extrusion, or dehulling and boiling, and they were then fine milled. Beans prepared by the standard method were also coarse milled. These five materials were incorporated into semi-purified diets (30% wt/wt) and fed to spontaneously hypertensive rats for 4 weeks. Body weight, blood pressure, and aorta morphology were unaltered by the diets. Fasting total cholesterol was significantly reduced in rats fed micronized beans compared with extruded beans (both fine-milled) or the bean-free diet, while boiling combined with coarse milling lowered low-density lipoprotein (LDL) cholesterol. The lack of cholesterol lowering in rats fed extruded bean compared to micronized was not explained by the amount or composition of dietary fiber or resistant starch. Differences in the polyphenolic profile as determined by high-performance liquid chromatography (HPLC) were also unable to explain the variations in cholesterol-lowering capacity. CONCLUSION: The present study demonstrates that processing of black beans alters the health effects observed with the whole pulse, and suggests that products prepared with processed ingredients will need to be tested empirically to establish whether the biological effects are maintained in vivo. © 2020 Society of Chemical Industry.

Regular Black Bean Consumption Is Necessary to Sustain Improvements in Small-Artery Vascular Compliance in the Spontaneously Hypertensive Rat.

Edible legume seeds, such as lentils, have been shown to modulate the structural and functional properties of hypertensive blood vessels, however, the effects of dried beans have not been similarly evaluated. To determine whether beans could attenuate hypertension-induced vascular changes (remodeling and stiffness) in relation to their phytochemical content, spontaneously hypertensive rats (SHR) were fed diets containing black beans (BB; high phytochemical content as indicated by their dark seed coat colour) or navy (white) beans (NB; low phytochemical content) for eight weeks. An additional follow-up phase was included to determine how long the alterations in vascular properties are maintained after bean consumption is halted. Assessments included blood pressure (BP), pulse wave velocity (PWV), vessel compliance (small-artery) and morphology (large-artery), and body composition. Neither BBs nor NBs altered BP or PWV in SHR. SHR-BB demonstrated greater medial strain (which is indicative of greater elasticity) at higher intraluminal pressures (80 and 140 mmHg) compared to SHR-NB. BB consumption for 8 weeks enhanced vascular compliance compared to SHR-NB, as demonstrated by a rightward shift in the stress-strain curve, but this improvement was lost within 2 weeks after halting bean consumption. BB and NB increased lean mass after 8 weeks, but halting BB consumption increased fat mass. In conclusion, regular consumption of BBs may be appropriate as a dietary anti-hypertensive strategy via their positive actions on vascular remodeling and compliance.

Chlorogenic acid from coffee beans: evaluating the evidence for a blood pressure-regulating health claim.

The consumption of coffee has been associated with a number of health benefits, including a reduced risk of cardiovascular disease. Hypertension is an important risk factor for adverse cardiovascular events. Coffee may help reduce blood pressure (BP) in humans, which might be attributable to its polyphenolic compound, chlorogenic acid. The high incidence of hypertension among Canadians underscores the need for new and effective strategies to reduce BP. Dietary interventions may constitute such a strategy, but consumers need to be informed about which foods are most effective for regulating BP. To guide healthy eating, Health Canada permits the use of health claims on the labels of foods that confer health benefits. Currently, there is only one health claim for BP regulation. Additional health claims for foods that assist in BP regulation are therefore warranted. This review provides background information on chlorogenic acid and examines the evidence regarding the use of chlorogenic acid for BP regulation in the context of Health Canada's health claims framework.