Introduction
We recently developed a novel edible keratin-derived protein (KDP) containing uniquely high concentrations of cysteine, glycine, and arginine [Glutathione is part of the thiol/disulfide system centred around the selenium-containing glutathione peroxidases (GPx) and thiol reductases, which in conjunction with peroxide scavenging enzymes (e.g., catalase and superoxide dismutase, SOD) and proteins, such as the highly abundant peroxiredoxins (PRX) mediate the transfer of redox state to cell signalling and metabolism [In a pilot study over 28-d in sedentary overweight mice, the ingestion of a 50/50 KDP/casein blend vs 100% casein lowered blood glucose (11 vs 19 mmol/L; difference 8 mmol/L, 90% confidence interval 5 to 11 mmol/L) [