The importance of molecular weight in determining the minimum dose of oat β-glucan required to reduce the glycaemic response in healthy subjects without diabetes: a systematic review and meta-regression analysis

• Published in: European journal of clinical nutrition Vol. 77; no. 3; pp. 308 - 315
• Main Authors: Noronha, Jarvis C., Zurbau, Andreea, Wolever, Thomas M. S.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.03.2023; Nature Publishing Group
• Subjects: 631/443/319; 692/700/2814; Avena; Blood Glucose - analysis; Carbohydrates; Clinical Nutrition; Confidence intervals; Diabetes; Diabetes Mellitus; Epidemiology; Feeding trials; Glucan; Glucose; Healthy Volunteers; Humans; Insulin; Internal Medicine; Meal feeding; Medicine; Medicine & Public Health; Metabolic Diseases; Molecular Weight; Oat bran; Public Health; Regression Analysis; Review; Review Article; Statistical analysis; Systematic review; β-Glucan
• DOI: 10.1038/s41430-022-01176-5
• ISSN: 0954-3007; 1476-5640

To determine the minimum amount of oat β-glucan (OBG) required to reduce glycaemic responses (MinDose), we conducted a systematic review and meta-regression analysis of acute, crossover, single-meal feeding trials that examined the effects of adding OBG or oat bran to a carbohydrate-containing test-meal versus a control test-meal containing an equivalent amount of available-carbohydrate (avCHO) from the same or similar source. Medline, Embase, and Cochrane Library were searched up to 18 August 2021. The primary outcome was glucose incremental-area-under-the-curve (iAUC). Secondary outcomes included insulin iAUC, and glucose and insulin incremental peak-rise (iPeak). Two independent reviewers extracted data. Results were expressed as ratio-of-means (RoM) with 95% confidence intervals (CIs). Linear associations were assessed by random effects meta-regression. MinDose was defined as the dose at which the upper 95% CI of the regression line cut the line of no effect (i.e., RoM = 1). Fifty-nine comparisons ( n  = 340) were included; 57 in healthy subjects without diabetes and two in subjects with diabetes; 24 high-MW (>1000 kg/mol), 22 medium-MW (300–1,000 kg/mol), and 13 low-MW (<300 kg/mol). In healthy subjects without diabetes the associations between OBG dose and glucose iAUC and iPeak were linear (non-linear p value >0.05). MinDoses for glucose iAUC for high-MW, medium-MW and low-MW OBG, respectively, were estimated to be 0.2 g, 2.2 g and 3.2 g per 30 g avCHO; MinDoses for glucose iPeak were less than those for iAUC. Insufficient data were available to assess MinDose for insulin, however, there was no evidence of a disproportionate increase in insulin. More high-quality trials are needed to establish MinDose in individuals with diabetes.