Increasing oat β-glucan viscosity in a breakfast meal slows gastric emptying and reduces glycemic and insulinemic responses but has no effect on appetite, food intake, or plasma ghrelin and PYY responses in healthy humans: a randomized, placebo-controlled, crossover trial

Abstract

Background The viscosity of oat β-glucan (OBG) determines its effect on serum cholesterol and glycemic responses, but whether OBG viscosity affects gastric emptying, appetite, and ad libitum food intake is unknown. Objectives We aimed to determine the effect of altering the amount or molecular weight (MW) and, hence, viscosity of OBG in a breakfast meal on the primary endpoint of food intake at a subsequent meal. Methods Overnight-fasted males (n = 16) and nonpregnant females (n = 12) without diabetes, aged 18–60 y, with BMI 20.0–30.0 kg/m² who were unrestrained eaters participated in a double-blind, randomized, crossover study at a contract research organization. Participants consumed, in random order, breakfast meals equivalent in weight, energy, and macronutrients consisting of white-bread, butter, jam, and 2% milk plus hot cereal [Cream of Rice (CR), or instant-oatmeal plus either 3 g oat-bran (2gOBG), 10 g oat-bran (4gOBG), or 10 g oat-bran plus β-glucanase (4gloMW) to reduce OBG MW and viscosity compared with 4gOBG]. Gastric emptying, subjective appetite, and glucose, insulin, ghrelin, and peptide tyrosine tyrosine (PYY) responses were assessed for 3 h and then subjects were offered an ad libitum lunch (water and pizza). Results Pizza intakes (n = 28) after CR, 2gOBG, 4gOBG, and 4gloMW (mean ± SEM: 887 ± 64, 831 ± 61, 834 ± 78, and 847 ± 68 kcal, respectively) were similar (nonsignificant). Compared with CR, 4gOBG significantly reduced glucose (78 ± 10 compared with 135 ± 15 mmol × min/L) and insulin (14.0 ± 1.6 compared with 26.8 ± 3.5 nmol × min/L) incremental area-under-the-curve and delayed gastric-emptying half-time (geometric mean: 285; 95% CI: 184, 442, compared with geometric mean: 105; 95% CI: 95, 117 min), effects not seen after 4gloMW. Subjective appetite, PYY, and ghrelin responses after 2gOBG, 4gOBG, and 4gloMW were similar to those after CR. Conclusions The results demonstrate that OBG viscosity determines its effect on postprandial glucose, insulin, and gastric emptying. However, we were unable to demonstrate a significant effect of OBG on appetite or food intake, regardless of its viscosity. This trial was registered at clinicaltrials.gov as NCT03490851.

Structural breakdown of starch‐based foods during gastric digestion and its link to glycemic response: In vivo and in vitro considerations

“…Contradictory to these studies, Wolever et al. (2019) reported a delay in the gastric emptying half‐time of breakfast cereals (semisolid) with higher viscosity, which in the study were consumed with bread (solid), and the delay was consistent until 90 min after consumption of the meals. The study also reported that higher viscosity of the semisolid phase of the test meals led to lower glycemic response of the meals.…”

β-Glucan Metabolic and Immunomodulatory Properties and Potential for Clinical Application

“…This study also demonstrated that viscosity would determine the effect of the β-glucans. It is hypothesized that by forming viscous solutions and retaining water in the digestive tract stool volume is increased and homeostasis of blood glucose levels are improved [ 37 , 94 ].…”

Detection of Beta-Glucan Contamination in Nanotechnology-Based Formulations

“…Second, beta-glucans are considered active ingredients in treatments aimed at improving immunity in a variety of disorders, including cancer [ 52 ]. Various forms of oral formulations are promoted worldwide as over-the-counter remedies, and some formulations are being also considered for either systemic or oral administration and undergoing clinical evaluation [ 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 ]. Third, β-(1,3)- d -glucans may become undesirable contaminants in pharmaceutical products, where they are inadvertently introduced during manufacturing either through certain types of personal protective equipment (PPE) suits and other cellulose-based materials (e.g., cellulose-acetate filters, cotton plugs) used in manufacturing facilities or from fungal contamination of starting materials (e.g., sucrose and sucrose-containing buffers), tools, and equipment [ 32 , 61 ] ( Table 2 ).…”