COLLAGEN WITH MAGNESIUM + VIT.C strawberry flavor from AMLSPORT . Collagen is the most abundant protein in the human body, being the main constituent of cartilage, tendons, bones (90%) and skin (70%). Proteins help to preserve muscle mass and maintain bones under normal conditions. Magnesium contributes to normal protein synthesis. Magnesium also contributes to the normal function of muscles and the nervous system and helps reduce tiredness and fatigue. Vitamin C contributes to the normal functioning of the immune system and helps reduce tiredness and fatigue.