a1 Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
a2 Department of Food Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada
Structural characteristics and baking conditions influence the metabolic responses to carbohydrate-containing foods. We hypothesized that consumption of whole wheat or sourdough breads would have a favourable effect on biomarkers of glucose homeostasis after first and second meals, compared with those for white bread. Ten overweight volunteers consumed 50 g available carbohydrate of each of the four breads (white, whole wheat, sourdough, whole wheat barley) followed 3 h later by a standard second meal. Blood was sampled for 3 h following bread ingestion and a further 2 h after the second meal for determination of glucose, insulin, paracetamol (indirect marker of gastric emptying), glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1). Glucose and GLP-1 responses to sourdough bread were lower (P < 0·05) than whole wheat and whole wheat barley breads. Glucose area under the curve (AUC) for sourdough bread was lower than those for whole wheat (P < 0·005) and whole wheat barley (P < 0·03) breads for the entire study. GIP AUC after sourdough bread ingestion was lower compared to white (P < 0·004) and whole wheat barley (P < 0·002) breads following the second meal. There were no significant differences in insulin and paracetamol concentrations among the test breads. Ultra-fine grind whole wheat breads did not result in postprandial responses that were lower than those of white bread, but sourdough bread resulted in lower glucose and GLP-1 responses compared to those of these whole wheat breads following both meals.
(Received August 22 2007)
(Revised April 14 2008)
(Accepted April 28 2008)
(Online publication June 23 2008)
Abbreviations: AUC, area under the curve; CHO, carbohydrate; Cmax, peak serum concentration; GIP, glucose-dependent insulinotropic polypeptide; GLP-1, glucagon-like peptide-1; Tmax, time until peak serum concentration