In a double-blind, placebo-controlled trial from 2018, 53 women aged 40-60 years were randomized to receive 1000 mg of low-molecular weight collagen peptide supplement (a fish-derived collagen hydrolysate) or placebo, daily for 12 weeks. The group given collagen had significantly higher values of skin-hydration after 6 weeks and 12 weeks. Several parameters of skin elasticity were also significantly higher in the collagen group.
References:
Kim D-U, Chung H-C, Choi J, et al. (2018). Oral intake of low-molecular-weight collagen peptide improves hydration, elasticity, and wrinkling in human skin: a randomized, double-blind, placebo-controlled study. Nutrients. 10(7): 826