Effects of milk and milk constituents on postprandial lipid and glucose metabolism in overweight and obese men.

Studies have suggested that two major milk constituents, casein and Ca, favourably affect postprandial responses. However, effects of milk on postprandial metabolism are unknown. We therefore investigated effects of using milk with a fat-containing meal on lipid and glucose responses in overweight men. To identify the constituent responsible for possible effects, we also studied responses to Ca and protein. A total of sixteen men (BMI > 27 kg/m(2)) participated in four postprandial tests. They consumed a breakfast (44 g of fat) plus a drink: a control drink, low-fat milk or a protein and Ca drink (500 ml). Blood samples were taken before the meals and at regular time points during 6 h thereafter. Compared with control, the incremental AUC (iAUC) for serum TAG was increased by 44% after the protein meal (P=0.015). Although the iAUC were not different (P=0.051), peak glucose concentrations were reduced by 24% after protein intake, as compared with control (P=0.021). The decrease of 18% after milk intake did not reach statistical significance. Compared with the milk meal, the iAUC for insulin was 52% lower after the control meal (P=0.035) and 51% after the protein meal (P=0.005). The present results indicate that the intake of milk with a fat-containing meal enhances postprandial TAG and insulin responses and may blunt glucose increases. The protein fraction of milk seems to be the main determinant for the effects on TAG and glucose. Ca did not change any of the postprandial responses.