Dietary fibre fermentability but not viscosity elicited the 'second-meal effect' in healthy adult dogs

The present study evaluated the effects of fibre fermentability and viscosity in a morning meal on glucose, insulin and glucagon-like peptide-1 (GLP-1) responses to a glucose challenge later in the day in six healthy female dogs. For this purpose, two Latin square design experiments were performed. In Expt 1, dogs were fed a low-fibre (LF; 1% Solka-Floc (International Fiber Corporation) and 1% soya hulls) diet, a low-fermentable fibre (LFF; 5% Solka-Floc (International Fiber Corporation) and 3% soya hulls) diet or a high-fermentable fibre (HFF; 5% pectin and 3% short-chain fructo-oligosaccharides) diet. In Expt 2, dogs were fed a low-viscosity fibre (5% Solka-Floc (International Fiber Corporation) and 3% soya hulls) diet, a moderate-viscosity fibre (MVF; 2% Solka-Floc (International Fiber Corporation), 2% soya hulls, 2% psyllium and 2% pectin) diet or a high-viscosity fibre (HVF; 4% psyllium and 4% pectin) diet. Dogs were fed at 08.00, 12.00 and 16.00 hours on days 1-6 of each period. On day 7, dogs were fed at 08.00 hours and then dosed with maltodextrin at 12.00 hours. Data were analysed to identify baseline and incremental AUC (IAUC) changes among the treatments. In Expt 1, glucose IAUC(0-180 min) was lower (P < 0.05) in dogs fed the HFF v. LF and LFF diets. Insulin and GLP-1 IAUC(0-180 min) were not affected. In Expt 2, baseline GLP-1 was greater (P < 0.005) and baseline insulin was lower (P < 0.05) in dogs fed the HVF v. MVF diet, but glucose, insulin and GLP-1 IAUC(0-180) min were not affected. In summary, HFF in a morning meal has the potential to decrease blood glucose response in a consequent meal.