Barley β-glucan increases fecal bile acid excretion and short chain fatty acid levels in mildly hypercholesterolemic individuals

Abstract

The cholesterol-lowering effect of barley β-glucan has been proposed to be the result of a pleiotropic effect, which involves several biological mechanisms such as gut fermentation, inhibition of intestinal cholesterol absorption and increased bile acid excretion and its synthesis. However, one of the recent studies from our laboratory indicated that increased bile acid excretion and subsequent increase in its synthesis, but not the inhibition of cholesterol absorption or synthesis might be responsible for the cholesterol-lowering effect of barley β-glucan. Accordingly, the primary objective of the present study was to investigate the concentration of bile acids (BA), neutral sterols (NS) and short chain fatty acids (SCFA) excreted through the feces by mildly hypercholesterolemic subjects who consumed diets containing barley β-glucan with varying molecular weights (MW) and concentrations. In a controlled, four phase, crossover trial, 30 mildly hypercholesterolemic but otherwise healthy subjects were randomly assigned to receive breakfast containing 3 g high MW (HMW), 5 g low MW (LMW), 3 g LMW barley β-glucan or a control diet for 5 weeks. The concentrations of BA, NS and SCFA in the feces were measured at the end of each treatment phase. Compared to the other treatment groups, 3 g day-1 HMW barley β-glucan consumption resulted in increased lithocholic acid (LCA) excretion (P < 0.001) but not LMW β-glucan, even at the high dose of 5 g day-1. Increased fermentability of fibre was also evident from a significant increase in fecal total SCFA concentrations in response to the 3 g HMW β-glucan diet compared to the 3 g LMW barley β-glucan and control diet (P = 0.0015). In summary, the current results validate our previous report on the role of fecal bile acid excretion in cholesterol lowering through the consumption of barley β-glucan. In addition, increased SCFA concentrations indicate that an increase in β-glucan molecular weight promotes hindgut fermentation, which might also be playing a role in attenuating cholesterol levels.

Anthocyanin extracts of lingonberry (Vaccinium vitis‐idaea L.) attenuate serum lipids and cholesterol metabolism in HCD‐induced hypercholesterolaemic male mice

“…As the bile acid is the converted product of cholesterol, its synthesis process in the liver has become the main pathway of cholesterol metabolism and cholesterol excretion (Chen et al ., ). It has been reported that chemical compounds such as lupin seed, paprika seed oil and β‐glucan in barley could be able to bind with bile acid in the intestine and promote the excretion of bile acid (Fontanari et al ., ; Chen et al ., ; Thandapilly et al ., ). This phenomenon consequently leads to greater amount of cholesterol converted to bile acid and results in the cholesterol‐lowering effect (Insull, ).…”

The effects of oat ingredients on blood pressure in spontaneously hypertensive rats

“…Antihypertensive treatment is known to improve cardiac filling properties and improve diastolic function (Mattioli et al, 2004;Muller-Brunotte, Kahan, Malmqvist, Ring, & Edner, 2006;Wachtell et al, 2002). In this study, beta-glucan treatment resulted in a absorbed into blood stream directly, the gut fermentation products generated by colonic microbiota such as short chain fatty acids (SCFAs) have been shown to regulate arterial BP (Thandapilly et al, 2018). For example, previous study showed that SCFA, propionate, induces vasorelaxation in rat mesenteric arteries (Khalesi, Sun, Buys, & Jayasinghe, 2014;Pluznick, 2017).…”

Bile Acids in Patients with Uncontrolled Type 2 Diabetes Mellitus – The Effect of Two Days of Oatmeal Treatment

“…When they reach the colon they can be degraded by the microbiota [16]. While the largely insoluble polysaccharide cellulose is quite resistant to fermentation, the well soluble β-glucans, that are found in high amounts in oats and barley, are subject to extensive fermentation leading to the production of short-chain fatty acids (SCFAs), some of which exert beneficial effects on human health [17,18].…”

“…Furthermore, β-glucans and other fibres have been shown to lower blood cholesterol concentrations, presumably by the binding of BAs and thereby decreasing their reabsorption [16,17,19]. This loss is compensated by increased synthesis of BA from cholesterol.…”