Collagen is found in its natural form in gelatine. A processed version of this protein – hydrolyzed collagen peptides – is a powdered form of collagen. The biggest difference between gelatine and collagen peptides is how they dissolve. Collagen peptide supplements dissolve easily in both hot and cold water and are thus easier to digest. Gelatine is soluble only in warm water, indicating that it may be harder to digest in the stomach.