Collagen is a foodstuff, a fibrous animal protein, which is present in all animal tissues, especially connective tissue. Collagen makes up 25 to 35 percent of human protein. Collagen has a slightly different structure and function depending on the type of tissue in which it is incorporated.
Gelatine is produced from collagen in a hydrolysis process.
In our mid-30s, the body's natural collagen production decreases at a rate of 1-2% per year and we start to develop fine lines and wrinkles in our skin.
Collagen is not an excipient but a food and therefore has no E number, but it can act as an excipient in some contexts.
For example, collagen is used as an excipient in Zymbion toothpaste and hydrolysed, easily absorbable collagen is used in the beauty preparation Evelle.