Objective The objective of this research was to investigate the effectiveness of daily ingestion of a specific collagen hydrolysate（CH）, which contains prolylhydroxyproline（Pro-Hyp）and hydroxyprolylglycine（Hyp-Gly）, on facial skin properties.
Methods In this randomized, placebo-controlled, double-blind trial, 56 women aged 30-55 years were randomized to receive 2.5 g of CH or 5 g of placebo once daily for 8 weeks, with 28 subjects assigned to each group. The hydration, elasticity and roughness properties of facial skin were measured at week 0（baseline）, week 4 and week 8.
Results Levels of skin hydration, elasticity and roughness in subjects who received CH significantly improved between baseline and weeks 4 and 8, while there was no significant improvement in subjects who received placebo. Moreover, the levels of skin elasticity, roughness and the net change of skin hydration improved significantly in the CH group compared to the placebo group by both weeks 4 and 8.
Conclusion The present results suggest that daily ingestion of 2.5 g of CH improves facial skin hydration, elasticity and roughness.