Ascorbyl Isostearate is an oil-soluble derivative of Vitamin C that can penetrate into the skin and there it is metabolized to Ascorbic Acid. Its efficacy is better than the one of pure Ascorbic Acid and resists discoloration and degradation while retaining all biological activity of L-Ascorbic Acid. It also shows excellent resistance to acid and heat as well as long-acting stability.