No matter which skin issues you’re currently bemoaning, chances are your routine could benefit from a vitamin C serum. The antioxidant is one of the few skin care ingredients dermatologists will back for its noticeable brightening, protective, and collagen-boosting properties. “Vitamin C is an antioxidant,” says dermatologist Kenneth Howe, M.D., at Wexler Dermatology. “When ultraviolet…