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

Noronha, J. C., Zurbau, A., & Wolever, T., M., S. (2022). The importance of molecular weight in determining the minimum dose of oat β-glucan required to reduce the glycemic response in healthy subjects without diabetes: A systematic review and meta-regression analysis. European Journal of Clinical Nutrition. doi.10.1038/s41430-022-01176-5

 

Abstract:

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 (>1000kg/mol), 22 medium-MW (3001,000kg/mol), and 13 low-MW (<300kg/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 0.2g, 2.2g and 3.2g per 30g 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.