Doctor's Best Pure Collagen Types 1 and 3 contains pure collagen protein, which contributes to the growth and maintenance of healthy tissues.* Collagen is the structural protein essential for the strength of bones and flexibility of joints, tendons, ligaments, hair, skin, nails, and other tissues throughout the body.* Collagen Types 1 and 3 Powder is enzymatically hydrolyzed into component peptides with a small molecular size for optimal absorption and utilization by the body.*