Author(s): Anne C Nilsson, Elin M stman, Jens J Holst, Inger M E Bjrck
Low-glycemic index (GI) foods and foods rich in whole grain are associated with reduced risk of type 2 diabetes and cardiovascular disease. We studied the effect of cereal-based bread evening meals (50 g available starch), varying in GI and content of indigestible carbohydrates, on glucose tolerance and related variables after a subsequent standardized breakfast in healthy subjects (n = 15). At breakfast, blood was sampled for 3 h for analysis of blood glucose, serum insulin, serum FFA, serum triacylglycerides, plasma glucagon, plasma gastric-inhibitory peptide, plasma glucagon-like peptide-1 (GLP-1), serum interleukin (IL)-6, serum IL-8, and plasma adiponectin. Satiety was subjectively rated after breakfast and the gastric emptying rate (GER) was determined using paracetamol as a marker. Breath hydrogen was measured as an indicator of colonic fermentation. Evening meals with barley kernel based bread (ordinary, high-amylose- or beta-glucan-rich genotypes) or an evening meal with white wheat flour bread (WWB) enriched with a mixture of barley fiber and resistant starch improved glucose tolerance at the subsequent breakfast compared with unsupplemented WWB (P < 0.05). At breakfast, the glucose response was inversely correlated with colonic fermentation (r = -0.25; P < 0.05) and GLP-1 (r = -0.26; P < 0.05) and positively correlated with FFA (r = 0.37; P < 0.001). IL-6 was lower (P < 0.01) and adiponectin was higher (P < 0.05) at breakfast following an evening meal with barley-kernel bread compared with WWB. Breath hydrogen correlated positively with satiety (r = 0.27; P < 0.01) and inversely with GER (r = -0.23; P < 0.05). In conclusion, the composition of indigestible carbohydrates of the evening meal may affect glycemic excursions and related metabolic risk variables at breakfast through a mechanism involving colonic fermentation. The results provide evidence for a link between gut microbial metabolism and key factors associated with insulin resistance.