High protein buckwheat flour suppresses hypercholesterolemia in rats and gallstone formation in mice by hypercholesterolemic diet and body fat in rats because of its low protein digestibility

This study evaluated the physiologic properties of high protein buckwheat flour (PBF) by examining its effects on serum cholesterol and body fat in rats and on cholesterol gallstone formation in mice. Animals were fed experimental diets that contained casein, buckwheat protein extract (BWP), or PBF as a protein source (net protein content 200 g/kg). In experiment 1, consumption of PBF and BWP for 10 d caused 33% and 31% decreases, respectively, in serum cholesterol of rats fed cholesterol-enriched diets when compared with consumption of casein (P < 0.05). Dietary PBF caused a significant decrease in liver cholesterol, whereas dietary BWP caused only a slight decrease (P > 0.05). Fecal excretion of neutral and acidic steroids in the PBF group was significantly higher than those in the BWP and casein groups. In experiment 2, consumption of PBF for 10 d significantly suppressed adipose tissue weight and hepatic activity of fatty acid synthase in rats fed cholesterol-free diets compared with consumption of casein (P < 0.05), whereas that of BWP for this period caused only a slight decrease in adipose tissue weight (P > 0.05). In experiment 3, dietary PBF and BWP significantly decreased the incidence of cholesterol gallstones and lithogenic index in mice fed cholesterol-enriched diets for 27 d, which was associated with increased fecal excretion of acidic steroids. This study demonstrated that PBF has strong activities against hypercholesterolemia, obesity, and gallstone formation, suggesting a potential usefulness of PBF as functional ingredient.