Ingestion of Salmon Nasal Cartilage-Derived Proteoglycan Improves Skin Condition: A Randomized, Double-Blind, Controlled Study

Background: Proteoglycan is one of the components of the extracellular matrix with various biological activities and has been used as the functional foods to improve knee joint health or skin condition. Objective: To examine the effect of ingestion of salmon (Oncorhynchus keta, Salmonidae) nasal cartilage-derived proteoglycan (sPG) on skin condition, we performed a randomized, double-blind, controlled study in healthy adult volunteers. Methods: Recruited subjects (n=156) were men and women, ages 21-62 years. From this population, we selected 19 subjects based on the exclusion criteria of the guidelines for evaluation of cosmetic functions of Japanese Cosmetic Science Society. Subjects were randomly divided into an sPG group (n=10; mean age, 39.1 years) and a placebo group (n=9; mean age, 39.6 years). The characteristics of the sPG used in this study were assessed by HPLC and electrophoresis analysis. Results: The safety was confirmed by the monitoring of all volunteer subjects for the development of adverse reactions. We found no negative information on the safety of proteoglycan ingestion and no evidence for an interaction between proteoglycan and other functional foods/medicine in several different databases. Viscoelasticity and recovery after deformation as the skin elasticity increased significantly in the sPG group compared to the placebo group (p<0.05). Skin looseness significantly decreased in the sPG group (p<0.05). Moreover, the number of wrinkles, conspicuous or darkened facial pores, and blotches significantly decreased in the sPG group (p<0.05). Measurements of skin conductance showed that sPG improved skin moisture and micrographs of facial corneocytes showed that sPG improved rough skin. Conclusion: Our results suggest the potential of sPG as a food ingredient to improve human skin condition, including skin elasticity, wrinkles, facial pores, blotches, moisture, and smoothness.