 But there is one type of vitamin C that has been shown to help. Skin biopsy studies show that the topical application of a 5% solution of elascorbic acid, also known as just a scorbic acid, the type of vitamin C found in food, significantly increases the expression of collagen in human skin compared to placebo, suggesting functional activity of the skin cells is not maximal in post-menopausal women and can be increased. A split-face study involving the application of three drops of a 10% elascorbic solution for three months found significant improvements over the placebo side of the face and finding coarse wrinkles, sourness, and skin tone or firmness. Not knowing which side was which, 16 out of 1984, percent of patients correctly identified the vitamin C side as the one showing improvement.