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

Abstract

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 boilingthe standard methodand 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.

Black Soybean and Adzuki Bean Extracts Lower Blood Pressure by Modulating the Renin-Angiotensin System in Spontaneously Hypertensive Rats

“…It was previously reported that 60% ethanol extracts of black soybeans improved TC, LDL-C, and HDL-C in overweight and obese adults in a randomized, double-blinded clinical trial [ 42 ]. Likewise, black soybeans processed by various methods, including boiling, freeze-drying, and coarse-milling, decreased TC and LDL-C levels in SHR [ 43 ]. Besides, a 40% ethanol fraction of hot-water extracts of adzuki beans improves hepatic lipid profiles with a reduction of TG (12%) and TC (7%) in the KKAy mice model [ 44 ].…”

Resistant starch in common beans: Concentration, characteristics, uses and health effects. A systematic map and review of the studies from 1962 to 2023

“…Common bean effect on hypercholesterolemia may be due also to its RS concentration, as also partly found by various authors modulating the presence of the RS from bean in model rats (Tanaka et al, 2019;Kilua et al, 2020;Zuo et al, 2022). Loader et al (2021) found scarce effect of various dies containing variable bean RS concentration on the body weight, blood pressure, and aorta morphology, but found a reduction of the fasting total cholesterol or low-density lipoprotein cholesterol International Journal of Food Science and Technology 2023 depending on either the bean cooking strategies and presence of bean in the diet. Unluckily, the former authors were unable to attribute the health effects to the presence of the RS or other fibres.…”

“…For example, and regarding hypertension, Loader et al (2021) found that micronized, but not extruded bean lowered the cholesterol of spontaneously hypertensive rats and such difference was not linked to either the amount or composition of DF or RS in both products.…”

“…A wealth of conditions including site of cultivation, milling procedure, moisture, genotype, cooking, fermentation, leavening agent and storage conditions can affect RS concentration in beans (Kutos et al ., 2003; Martín‐Cabrejas et al ., 2004; Vargas‐Torres et al ., 2004a, 2004b, 2006; Aguilera et al ., 2009; Yadav et al ., 2010a; Li et al ., 2011; Ovando‐Martínez et al ., 2011b; Piecyk et al ., 2012, 2013; Liu et al ., 2013; Arce‐Arce et al ., 2014; Hooper et al ., 2017, 2019, 2021; Santiago‐Ramos et al ., 2018; Escobedo et al ., 2020; Bento et al ., 2021; Loader et al ., 2021; Mendes et al ., 2021; Choe et al ., 2022; Guldiken et al ., 2022). However, studies on the role of the agronomic management on the RS concentration are almost absent, with the exception, in the present work, of two reports on the water availability (Herrera et al ., 2021; Salas‐Lumbreras et al ., 2023), both of which found that terminal drought, but not a restricted irrigation during the whole cycle, reduced the RS concentration in two common bean genotypes compared to a full irrigation during the whole cycle.…”

“…Loader et al . (2021) found scarce effect of various dies containing variable bean RS concentration on the body weight, blood pressure, and aorta morphology, but found a reduction of the fasting total cholesterol or low‐density lipoprotein cholesterol depending on either the bean cooking strategies and presence of bean in the diet. Unluckily, the former authors were unable to attribute the health effects to the presence of the RS or other fibres.…”