Collagen synergy with other nutrients such as vitamins and minerals. Vitamin D contributes to the maintenance of bones in normal conditions and the normal functioning of muscles. Additionally, zinc helps normal metabolism of macronutrients and normal protein synthesis. Vitamin C contributes to the normal formation of collagen for the normal functioning of the skin, blood vessels, bones, cartilage, teeth and gums. Instructions for use: Take 1 capsule a day with water.