Milk as a supplement to mixed meals may elevate postprandial insulinaemia

Objective: The objective was to evaluate the impact of milk added to a high-glycaemic index (GI) white bread meal vs a low-GI spaghetti meal, respectively, on postprandial glucose and insulin responses in healthy subjects. Design: The volunteers were served the bread or spaghetti meals with either milk (200 or 400 ml, respectively) or water (400 ml) following an overnight fast. Capillary blood samples were collected before and during 3 h after the meals. Setting: The study was performed at the Department of Applied Nutrition and Food Chemistry, Lund University, Sweden. Subjects: Ten healthy volunteers, seven men and three women, aged 22 - 30 y, with normal body mass indices, were recruited. Results: There was no difference in postprandial glucose area under curve (AUC) with and without added milk in the case of the high-GI bread meals. As could be expected, glucose AUC after the bread meal + water was higher than after the spaghetti meal + water. Milk added at 200 or 400 ml to the spaghetti meal did not affect glucose AUC. However, a significantly higher insulin AUC was seen with the bread meal with 400 ml milk ( + 65%) and the spaghetti meal with 200 ml or 400 ml milk ( + 300%), respectively, compared with corresponding test meal with water. Conclusions: The addition of milk to a low-GI spaghetti meal may significantly increase the postprandial insulinaemia. Even an ordinary amount of milk (200 ml) increased the insulin AUC to a low-Gl spaghetti meal to the same level as seen with white bread. The mechanism for the insulinotrophic effect of milk is not known, and the potential long-term metabolic consequences need to be elucidated.