Two Week Keratin-Based Protein Supplementation is Comparable in Gastrointestinal Handling to a Milk-Based Equivalent

Keratins are a family of fibrous structural proteins that provide functional rigidity to a large number of animal tissues. They have long been present in the human diet; normally eaten in conjunction with animal food sources, such as when skin and hair are consumed. Certainly, keratin proteins ingested in this manner contribute only small proportions of total protein intake, and their bioavailability may be much lower than other proteins. Larger quantities of keratin are present within animal tissues with rigid protein matrices such as feathers and wool. Isolation of keratins from these tissues yields a digestible raw protein product with potentially significant nutritional value. The naturally high levels of the amino acid cysteine in keratin suggest potential for dietary enhancement of the biological thiols taurine and glutathione, which have diverse and important roles in health including potent antioxidant activity [1,2]. Furthermore, keratins are a source of mixed amino acids which may have broad application as a protein supplement. Processing of animal tissues into a raw keratin product would allow levels of consumption that vastly exceed those from traditional sources. Therefore, robust testing of keratin protein ingestion in quantities that represents a substantial proportion of typical daily protein intake is warranted.