The Effect of Oat β-Glucan on Postprandial Blood Glucose and Insulin Responses: A Systematic Review and Meta-Analysis

OBJECTIVES: The efficacy of oat beta-glucan (OBG), a viscous soluble fibre, on postprandial glycemic outcomes may depend on the nature of the control and the dose and molecular weight (MW) utilized. We undertook a systematic review and meta-analysis of acute clinical trials to determine whether these features mediate the glycemic and insulinaemic responses to OBG. METHODS: MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched through October 27, 2020. We included acute, single-meal feeding, controlled trials investigating the effect of OBG (concentrate or oat bran) added to a carbohydrate-containing meal compared to a comparable meal (matched control) or a different carbohydrate-containing meal (unmatched control). Two reviewers extracted the data and assessed the risk of bias and certainty of evidence (GRADE). The primary outcome was incremental area under the curve (iAUC) for blood glucose. Data were pooled using the generic-inverse variance method with random effects model and expressed as ratio of means with [95% Cis]. RESULTS: One hundred and three trial comparisons (N = 538) were included. OBG reduced glucose iAUC and iPeak by 23% (0.77 [0.74, 0.81]) and 28% (0.72 [0.64, 0.76]) and insulin by 22% (0.78 [0.72, 0.85]) and 24% (0.76 [0.65, 0.88]), respectively. Dose, molecular-weight and comparator were significant effect modifiers of glucose iAUC and iPeak. Significant linear dose-response relationships were observed for all outcomes. OBG molecular-weight > 300 kg/mol significantly reduced glucose iAUC and iPeak, whereas, molecular-weight