Extracted Oat and Barley β-Glucans Do Not Affect Cholesterol Metabolism in Young Healthy Adults

Abstract

β-Glucans are known to exhibit hypocholesterolemic effects. Increased intestinal viscosity is thought to be crucial for cholesterol lowering. It is suggested that concentration, molecular mass, and structure, including the ratio of (1→3) to (1→4) glucan bonds in the molecule, are of importance for β-glucan functionality. This study investigated the effects of 3 different β-glucan sources, incorporated into a beverage and yogurt, on blood lipids and fecal endpoints. Fourteen participants completed this randomized, crossover, single-blinded study with four 3-wk periods: control and 3.3 g/d oat, barley, and barley mutant β-glucans of similar molecular mass. Before and after each period, fasting and postprandial blood samples were drawn and 3-d fecal samples were collected. Treatment did not affect changes in total, LDL, and HDL cholesterol compared with control; however, consumption of 3.3 g/d of oat β-glucans for 3 wk resulted in greater decreases in total (-0.29 ± 0.09 mmol/L, P < 0.01), LDL (-0.23 ± 0.07 mmol/L, P < 0.01), and HDL (-0.05 ± 0.03 mmol/L, P < 0.05) cholesterol compared with baseline. Changes in LDL in the β-glucan treatments were not related to β-glucan structure (cellotriosyl:cellotetraosyl). Decreases in fasting triacylglycerol were substantially greater after oat β-glucan treatment compared with control (P = 0.03). Fecal dry and wet weight, stool frequency, fecal pH, and energy excretion were unaffected. The results do not fully support the hypocholesterolemic effects by differently structured oat and barley β-glucans. However, substantial differences compared with baseline suggest a potential for oat β-glucan, presumably due to its higher solubility and viscosity. This underlines the importance of elusive structural β-glucan features for beneficial physiologic effects.

Hypocholesterolaemic effect of probiotic yogurt enriched with barley β-glucan in rats fed on a high-cholesterol diet

“…It was suggested that the hypocholesterolemic effects of ␤-glucan might be due to the enhancement of CYP7A1 expression resulting from increased fecal excretion of bile acids. On the other hand, ␤-glucan extracted from oat and barley did not affect cholesterol metabolism in young healthy adults [27].…”

“…Increased intestinal viscosity is thought to be crucial for cholesterol lowering. Concentration, structure, and molecular weight, play important roles in ␤glucan functionality [27]. ␤-glucans decreased serum total cholesterol (18.9%), and LDL-cholesterol (24.3%) in Sprague-Dawley rats [28].…”

Biological Attributes of Unfermented and Fermented Oat Milk Compared to Cow Milk in Alloxan-Induced Diabetic Rats

“…β-glucans decreased serum total cholesterol (18.9%) and LDL-cholesterol (24.3%) in Sprague-Dawley rats. Addition of β-glucan resulted in increased bile acid secretion , Lambo et al, 2005, Baroutkoub et al, 2010, Bruckert, 2006Yang et al, 2003, Ibrugger et al, 2013, Ahmed et al, 2017,and Grundy et al, (2018).…”

Oat bran β-glucan improves glucose homeostasis in mice fed on a high-fat diet

“…Although the fundamental importance of b-glucan to the induced health benets has been widely accepted as discussed above, there are also reports showing no function of b-glucan in cholesterol metabolism and glucose tolerance. 20,21 The study of the pasting property of oat our and its bile acid binding capability also showed the importance of interactions among starch, protein, and b-glucan. 22 Additionally, the oat bran is a food processing-related term without exact composition requirement according to the standard, and its processing-dependence implies the difficulty to produce the exact same oat bran samples in both composition and physical form (such as particle size) in the industrial production.…”