Vitamin C, deemed “The Holy Grail of Skin-Care Ingredients” by Allure, is a powerful antioxidant that can neutralize free radicals and help brighten and repair damaged skin. Due to its highly acidic properties, it is also thought to kickstart collagen and elastin production to smooth and plump skin and prevent further damage. The most common form used in skincare is L-ascorbic acid, as it is more stable and thus more effective.