Each type of collagen (I, II, III, V, and X) has research behind it for supporting healthy skin, connective tissue, and more.(3) 3) Avila Rodríguez MI, Rodríguez Barroso LG, Sánchez ML. Collagen: A review on its sources and potential cosmetic applications. J Cosmet Dermatol. 2018 Feb;17(1):20-26. doi: 10.1111/jocd.12450. Epub 2017 Nov 16. PMID: 29144022.