Abstract
Consumption of low glycemic index (GI) foods has been associated with beneficial health effects. Underlying mechanisms are not yet fully elucidated.We aimed to investigate the differences in postprandial glucose kinetics and metabolic response after consumption of a high and a low GI fiber‐rich wheat bread, obtained by varying wheat particle size.In a randomized crossover study ten healthy male volunteers consumed 13C‐enriched wheat breads with different structures; a control bread (CB) made from wheat flour combined with wheat bran, and a kernel bread (KB) in which 85% of the flour was substituted with broken wheat kernels. The use of a dual isotope technique enabled calculation of in vivo glucose kinetics: rate of appearance of exogenous glucose, endogenous glucose production, and glucose clearance rate. In addition, postprandial plasma concentrations of glucose, insulin, glucagon and incretins were analyzed.Despite the attempt to create a low GI bread by the substitution of flour by broken kernels, the glycemic response and the glucose kinetics were quite similar after consumption of CB and KB. Interestingly, the incretin glucagon‐like peptide‐1 (GLP‐1) response was much lower after KB compared to CB (iAUC, P < 0.005).Thus, substitution of 85% wheat flour by broken kernels in bread did not result in a difference in glucose response and kinetics, but in a pronounced difference in GLP‐1 response. Changing the processing conditions of wheat for baking bread can influence the metabolic response beyond glycemia.
Highlights
Consumption of foods with a low glycemic index (GI) instead of those with a high GI is considered beneficial for health, being associated with a decreased risk for the development of obesity, insulin resistance, and type 2 diabetes (T2DM) [1,2,3,4,5], this association is not alwaysEur J Nutr (2017) 56:1063–1076 found [6]
The postprandial glycemic response obviously depends on intestinal glucose influx, but is influenced by suppression of endogenous glucose production (EGP) and increased glucose uptake in tissues, processes that are mainly regulated by the pancreatic hormones insulin and glucagon
The insulin response was lower after kernel bread (KB) consumption compared to control bread (CB) at t = 60 min (P = 0.002) (Fig. 3b), which resulted in a 31 % smaller Incremental areas under the curve (iAUC) (0–2 h) compared with CB intake (NS, P = 0.011)
Summary
Consumption of foods with a low glycemic index (GI) instead of those with a high GI is considered beneficial for health, being associated with a decreased risk for the development of obesity, insulin resistance, and type 2 diabetes (T2DM) [1,2,3,4,5], this association is not alwaysEur J Nutr (2017) 56:1063–1076 found [6]. The incretin hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1), released postprandial from intestinal K and L cells, respectively, are known to potentiate the insulin response to a carbohydrate-rich meal and are important factors in glucose metabolism. Besides their role as incretin hormones, GIP is involved in fat metabolism [8], and GLP-1 is involved in decreasing gastric emptying rate [9], suppression of glucagon [10], as well as increasing satiety [11], and, in rodents, preserving β-cell function [12]. BAs, as well as (indirectly) the gastrointestinal hormone cholecystokinin (CCK) which stimulates gall bladder contraction, might play a role in glucose metabolism after consumption of a carbohydrate-rich meal
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