Oral supplementation of specific collagen peptides has beneficial effects on human skin physiology: a double-blind, placebo-controlled study

Proksch E, Segger D, Degwert J, Schunck M, Zague V, Oesser S · Skin Pharmacology and Physiology

The one place the collagen-peptide literature tested two doses head to head against placebo. Skin elasticity improved significantly over placebo in BOTH the 2.5 g and the 5.0 g arm, with no advantage to doubling the dose. Skin moisture and transepidermal water loss moved in the right direction in subgroup analysis but did not reach significance.

Population

Women aged 35-55

Intervention

2.5 g or 5.0 g collagen hydrolysate once daily for 8 weeks

Comparator

Placebo

Limitations

Twenty-three women per arm, so it is underpowered to detect a modest difference between the two doses; a flat result here is weak evidence of a plateau rather than proof of one. Skin rather than joint. Same Collagen Research Institute co-authorship and GELITA-linked product as the wrinkle trial.