A study out of Korea involving women (aged 43-86) found that consuming 320mg of cocoa flavanols significantly improved skin elasticity and wrinkles. The amount of cocoa flavanols would be present in 50 to 340 g per day of dark chocolate depending on the types of dark chocolate. Milk chocolate would not be expected to be as effective as dark chocolate, because the presence of milk may inhibit the absorption of cocoa flavanols.
Supplements such as vitamins A, C and E along with alpha lipoic acid are also helpful in not only reducing wrinkles but also preventing them.