- Pure, Buffered Vitamin C Powder.Vitamin C is an essential nutrient well known for its vital role in immune system function. It is a highly effective antioxidant that can protect the body's structures from oxidative damage generated during normal metabolism. Vitamin C is also necessary for the production of collagen and is therefore important for skin, bone, and joint health. It is also needed for amino acid metabolism and the utilization of many nutrients, such as folic acid and iron. This product supplies Calcium Ascorbate C, a buffered form of Vitamin C that is bioavailable and non-acidic.