About the book: 2021 / Collagen is the most abundant protein in the body, its most important “building element.” Collagen improves the condition of the skin, muscles and tendons, intervertebral discs, and blood vessels. Collagen is believed to help reduce anxiety and improve mood, it controls weight and normalizes bowel function. And according to the latest research, collagen slows down aging, promotes tissue regeneration and strengthens the immune system.