I like the product, as the amino acids proline and lysine are 40% of the total that make up collagen. Lysine cannot be made by the body...it must be obtained from the diet, and since I have poor digestion, I don't get enough to maintain sufficient collagen. Collagen is the most abundant protein in the body and literally holds together the body tissue, including skin, blood vessels, and all connective tissue like muscle, tendons, organ tissue etc. An aortic or brain aneurysm can develop due to lack of collagen.