MARINE COLLAGEN WITH MAGNESIUM + VIT. C watermelon flavor by ANA MARÍA LAJUSTICIA . Collagen is the most abundant protein in the human body, being the essential constituent of cartilage, tendons, bones (90%) and skin (70%). Proteins contribute to the maintenance of bones in normal conditions, and to preserve and increase muscle mass. Magnesium helps reduce tiredness and fatigue, and contributes to normal protein synthesis and the maintenance of normal bones. Vitamin C improves the absorption of iron and contributes to the normal formation of collagen for the normal function of blood vessels, bones and cartilage.