Keyora Skin Systems Nutrition - Collagen Tripeptides EP-4: The Oral Peptide Absorption-to-Function Framework: From Human Gly-Pro-Hyp Pharmacokinetics to Experimental Dermal Distribution and Skin Outcomes

Oral collagen bioavailability is frequently inferred from ingredient dose, average molecular weight, or tripeptide enrichment, although none independently identifies the peptides entering human circulation or establishes skin efficacy. Keyora Skin Systems Nutrition - Collagen Tripeptides EP-4 introduces the Keyora Oral Peptide Absorption-to-Function Framework, integrating gastrointestinal transformation, sequence-specific human pharmacokinetics, experimental tissue distribution, and preparation-matched clinical skin outcomes. Chapter 1 examines the gastrointestinal fate of collagen-derived peptides. Gastric and pancreatic proteolysis, intestinal brush-border enzymes, PEPT1-associated transport, and intracellular metabolism can alter peptide identity before systemic appearance. Experimental studies demonstrate both Gly-Pro-Hyp (GPH) cleavage into glycine and Pro-Hyp and intact GPH passage across cultured intestinal barriers. These model-specific findings cannot establish absolute human absorption percentages. Chapter 2 evaluates human evidence from Iwai, Ohara, Yamamoto, Kleinnijenhuis, and Virgilio. Their studies identify circulating hydroxyproline-containing peptides, including GPH, Pro-Hyp, and Hyp-Gly, following characterized collagen preparations. Interpretation requires the actual intervention, molecular analyte, participant population, sampling schedule, and analytical method. Detection, concentration, and cumulative exposure are distinct measurements. Chapter 3 develops the Keyora Human Pharmacokinetic Evidence Matrix, connecting ingredient composition, administered sequence dose, plasma Cmax, Tmax, AUC, and preparation-specific comparisons. Yamamoto et al. (2016) demonstrated different GPH and Pro-Hyp profiles after CTP-100, CTP-50, and conventional collagen peptides. However, equivalent powder doses delivered unequal GPH quantities, preventing a simple conclusion of superior fractional absorption. Studies by Shigemura, Taga, and Virgilio further demonstrate dose-dependent and peptide-specific kinetic heterogeneity. Chapter 4 establishes the Keyora Dermal Continuity Map. Yazaki et al. (2017) measured GPH and Pro-Hyp in human plasma and separately detected these peptides in mouse skin. Kawaguchi et al. (2012) investigated radiolabeled Pro-Hyp distribution and metabolism in rats. Experimental fibroblast responses provide additional mechanistic context. Nevertheless, animal tissue concentrations, tracer-associated material, cellular responses, and human dermal delivery remain distinct evidence objects. Chapter 5 applies these findings to Keyora's tilapia-scale-derived collagen ingredient, providing 1,500 mg per two-tablet serving, a reported 459 Da mean molecular weight, and a declared 30% tripeptide fraction. These specifications do not establish intact GPH dosage or product-specific pharmacokinetics. Low-dose randomized trials by Kim, Tak, Lee, and Miyanaga report selected hydration, barrier, elasticity, or wrinkle responses, while meta-analytic findings remain sensitive to study quality and methodological differences. None directly validates the finished Keyora formulation. The framework proposes a staged verification pathway: molecular characterization → sequence-specific human exposure → experimental tissue evidence → collagen-only clinical testing → finished-formula evaluation. Its central conclusion is that circulating collagen peptides demonstrate systemic exposure, but human dermal delivery, biological utilization, and clinical skin efficacy require independent, preparation-matched evidence.