Protein Distribution Needs for Optimal Meal Response

Abstract

The adequacy of the RDA for protein (0.8 g/kg/d) continues to generate much scientific discussion. In particular, recent research suggests that adults require approximately 30 g of protein per meal to maximally stimulate muscle protein synthesis. The objective of this study was to assess the effect of daily protein distribution on muscle protein anabolism. Adult men and women participated in a randomized crossover 24 h study evaluating two diets each containing 90 g total protein/day. Diet 1 provided an even protein distribution: 30 g (breakfast), 30 g (lunch) and 30 g (dinner). Diet 2 provided a skewed protein distribution: 10 g (breakfast), 15 g (lunch) and 65 g (dinner). Stable isotope methodology with muscle biopsies and blood sampling was used to assess muscle protein synthesis in response to the breakfast meal (10 vs. 30 g protein) and the 24 h response. Visual analog questionnaires measured satiety. Preliminary results suggest muscle protein synthesis following the breakfast meal and after 24 h was approximately 25% greater in the evenly distributed protein group compared to the skewed diet. Indices of satiety were also improved following consumption of the evenly distributed protein diet. In conclusion, evenly distributing protein over the course of the day may promote increased utilization of dietary protein and greater satiety in adults.