Vitamins and Antioxidants

In practice, there's no proof that topically applied vitamins or antioxidants do much at all. Nor is it known whether they remain active long enough to prevent cell damage, promote new collagen production, or confer other benefits.

Vitamin C (ascorbic acid), for example, quickly loses potency when exposed to the air. Thus, it's unlikely that vitamin C in skin creams offers much benefit. Vitamin E (alpha tocopherol) is believed to improve the appearance of scars and help speed wound-healing, but there's no evidence that it does. And in some people, topical vitamin E causes allergic reactions.

Most studies have examined vitamins C and E as potential ingredients in sunscreens rather than as agents meant to reduce or prevent wrinkles. They've demonstrated some effectiveness against UVA and UVB damage. But only vitamins taken internally qualify as antioxidants.
Source: LHJ.com - Ladies’ Home Journal online