Plain language summary
The health effects of dairy products on cardiovascular disease (CVD), diabetes, obesity and total mortality may depend on their varying composition. This study aims to examine the long-term effects of milk proteins (whey and casein) and milk with a high or low content of medium-chain saturated fatty acids (MC-SFAs) on postprandial lipid metabolism. In this randomised, parallel-controlled, double-blinded, 12-week intervention study, 63 abdominally obese individuals were randomised to one of four diets, containing different compositions of whey, casein and MC-SFAs. Results showed that whey compared to casein significantly decreased postprandial apoB-48, independently of the fatty acid composition. Fasting and postprandial triacylglycerol and FFA responses were independent of protein or fatty acids composition. Authors conclude that 12-week supplementation with whey protein reduces postprandial apoB-48 compared to casein, indicating a beneficial effect on CVD risk.
Abstract
BACKGROUND Abdominal obesity and exaggerated postprandial lipemia are independent risk factors for cardiovascular disease (CVD) and mortality, and both are affected by dietary behavior. OBJECTIVE We investigated whether dietary supplementation with whey protein and medium-chain saturated fatty acids (MC-SFAs) improved postprandial lipid metabolism in humans with abdominal obesity. DESIGN We conducted a 12-wk, randomized, double-blinded, diet intervention study. Sixty-three adults were randomly allocated to one of 4 diets in a 2 × 2 factorial design. Participants consumed 60 g milk protein (whey or casein) and 63 g milk fat (with high or low MC-SFA content) daily. Before and after the intervention, a high-fat meal test was performed. We measured changes from baseline in fasting and postprandial triacylglycerol, apolipoprotein B-48 (apoB-48; reflecting chylomicrons of intestinal origin), free fatty acids (FFAs), insulin, glucose, glucagon, glucagon-like peptide 1 (GLP-1), and gastric inhibitory polypeptide (GIP). Furthermore, changes in the expression of adipose tissue genes involved in lipid metabolism were investigated. Two-factor ANOVA was used to examine the difference between protein types and fatty acid compositions, as well as any interaction between the two. RESULTS Fifty-two participants completed the study. We found that the postprandial apoB-48 response decreased significantly after whey compared with casein (P = 0.025) independently of fatty acid composition. Furthermore, supplementation with casein resulted in a significant increase in the postprandial GLP-1 response compared with whey (P = 0.003). We found no difference in postprandial triacylglycerol, FFA, insulin, glucose, glucagon, or GIP related to protein type or MC-SFA content. We observed no interaction between milk protein and milk fat on postprandial lipemia. CONCLUSION We found that a whey protein supplement decreased the postprandial chylomicron response compared with casein in persons with abdominal obesity, thereby indicating a beneficial impact on CVD risk. This trial was registered at clinicaltrials.gov as NCT01472666.
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