Small peptides in the range of 2 - 12 amino acids are believed to cross the intestinal wall undigested and enter the circulation where they can have a range of activities based on their amino acid composition and structure. Natural peptides isolated from a number of food proteins, including plants and marine organisms, are shown to have antioxidant effects in in vitro tests, and anti-hypertensive effects in mice through inhibition of the angiotensin-converting-enzyme (ACE). Protein hydrolysates from both animal- and plant-based sources will consist of a mixture of potentially bioactive peptides that can have specific effects based on their composition. Studies have shown that egg- and soy-derived hydrolysates have anti-diabetic and anti-obesity properties in rodents. Pre-clinical studies in mice have demonstrated potent plasma cytokine lowering abilities and atherosclerosis-prevention by chicken protein hydrolysate (CPH) diets, as well as effects on plasma cholesterol level, cytokines and lipid metabolism, including mitochondrial function. In addition, an isolated peptide fraction from chicken inhibits the dipeptyl peptidase IV, and thus has the potential to restore glucose homeostasis in type 2 diabetics.~The hydrolysate supplements used in this study are obtained from rest raw materials (RRM) from mechanical deboning of chicken meat (Food Grade, Nortura AS Hærland, Norway). Freshly minced chicken RRM has been treated with enzymes optimized to generate bioactive hydrolysates. The supplement is given in a dose of 18 g protein per day, corresponding to the protein content of a standard meal, and similar to doses recommended in protein shake supplements.~Around 60 males and females age >20 years with abdominal obesity participate, recruited primarily through social media advertisements (Facebook) limited to a 12 km radius around the city center of Bergen. Participants provided written informed consent, and were screened via self-reporting in an online form in EasyTrial hosted by the Research Unit for Clinical Trials at the University of Bergen. Data collection by the study staff at baseline verifies inclusion and exclusion criteria and participant eligibility prior to randomization. The potential participants are informed about practical details at a digital or physical meeting 1-2 weeks prior to baseline.~Groups of participants (40-60% males/females) are block randomized to the two treatments (CPH or placebo casein supplementation) using randomly selected block sizes, and stratified according to sex.~The participants are given a container with the powder sufficient for the entire 12-week study period, and a spoon to measure the intake at breakfast (6 g), lunch (6 g) and supper (6 g), or morning (9 g) and evening (9 g) according to individual preference. The patients will mix the powder products in water or mineral water.
In this randomized, placebo controlled, double blind trial, effects of relatively high doses of chicken protein hydrolysate (CPH) or casein hydrolysate (placebo) supplementation will be investigate in healthy persons with abdominal obesity. The 12-week study examines potential effects on body weight, abdominal obesity, body composition, plasma parameters of metabolic health including lipids, inflammatory parameters, redox state and microbiota biomarkers.