The Journal of Nutrition Nutrient Physiology, Metabolism, and Nutrient-Nutrient Interactions Casein Compared with Whey Proteins Affects the Organization of Dietary Fat during Digestion and Attenuates the Postprandial Triglyceride Response to a Mixed High-

Background: Postprandial lipemia is a risk factor for cardiovascular disease. The potential impacts of the type/nature of dietary protein on postprandial lipemia and associated dysregulations have been insufficiently investigated. Objective: We investigated the postprandial effect of including in a high-fat meal some milk protein fractions that markedly differ in their physicochemical properties and composition [either casein (CAS), whey protein (WHE), or a-lactalbumin-enriched whey protein (LAC)]. Methods: The protein fractionswere incorporated as 15%energy in a high-fat meal in a 3-period, crossover postprandial study of 10 healthy overweight menwith an elevatedwaist circumference (>94 cm).Wemeasured postprandial changes in plasma lipids, amino acids, glucose, andoxidative stressmarkers, vascular function (using pulse contour analysis), and low-grade inflammation (using plasma markers).We also characterized in vitro themeal structures, including the size of the fat globule, and possible changes during digestion. Results: The type of protein did not affect postprandial plasma glucose, amino acids, insulin, or nonesterified fatty acids, but, compared with WHE and LAC, which did not differ, CAS markedly reduced postprandial triglycerides (TGs), achieving a 22 6 10 % reduction in the 6-h area under the curve (P < 0.05). Similar trends were shown for plasma chylomicrons [apolipoprotein (apo)B-48; P < 0.05]. However, there were no significant differences between the meals regardin