Collagen is an insoluble fibrous protein that is the foundation of healthy cartilage, tendons, cartilage, skin and other connective tissue. There are over 15 types of collagen that are the building blocks of the human body. It is the most abundant protein in the body. As one ages, the creation of collagen in the body slows down, resulting in joint stiffness, a reduction in ligament and tendon elasticity and thin, weak skin. Eating fermented foods that contain probiotics such as homemade yogurt, kefir and sauerkraut plays an important role in influencing the health of collagen in the body. For example, eating probiotic foods influences the health of skin due to the impact of good bacteria on systemic inflammation throughout the body, tissue lipid content and glycemic control. Atopic dermatitis, psoriasis, acne and rosacea are all skin conditions that can be helped by eating probiotic foods.