Previous data show that proteins enhance satiety, decrease hunger and decrease energy intake. In addition, amino acids from dietary protein act as building blocks for de novo protein synthesis and consumption of dietary protein therefore stimulates protein synthesis. Proteins from different sources differ in amino acid composition and rate of absorption. Previously, studies on the effects of proteins on especially muscle protein synthesis has focused on milk proteins, whey and casein as animal sources, but other protein sources high in essential and branched-chain amino acids may also have beneficial effects on muscle protein synthesis and appetite. Thus, in this study the effects of two hydrolysed porcine proteins (one from porcine blood and one from porcine muscle) on muscle protein synthesis, appetite and secretion of gastrointestinal hormones will be compared with the effects of hydrolysed whey protein. These porcine proteins have never previously been tested and it is hypothesised that they may induce similar effects as hydrolysed whey protein due to the high contents of essential and branched-chain amino acids.~The study will be conducted as a randomised, 3-way, cross-over study. It consists of three visits separated by at least two weeks. It is expected that 18 normal-weight, young men will complete the study. They will be randomised to the order of the three proteins; hydrolysed porcine protein from blood (HPB), hydrolysed porcine protein from muscle (HPM) and hydrolysed whey protein (HW). At each visit the effects on muscle protein synthesis, appetite and secretion of gastrointestinal hormones will be measured/assessed. Muscle protein synthesis will be measured after consumption of a low (15 g) and a high (30 g) dose of protein and appetite and secretion of gastrointestinal hormones will be measured after the high protein dose (30 g). The effect on muscle protein synthesis will be measured by a flood-primed continuous infusion of labelled (Ring13C6) phenylalanine, muscle biopsies and blood samples. The effects on appetite will be assessed by visual analogue scales, an ad libitum meal and blood samples.
The purpose of the study is to obtain a better understanding of how hydrolysed porcine proteins affect the human metabolism, including the effects on muscle protein synthesis, appetite and secretion of gastrointestinal hormones.~It is hypothesised that hydrolysed porcine proteins will stimulate muscle protein synthesis, affect appetite and the secretion of gastrointestinal hormones similar to hydrolysed whey protein.