Tuna-and other omega-3-rich fish, such as salmon and sardines-may help keep your skin looking youthful and prevent skin cancer. EPA (eicosapentaenoic acid), one of the omega-3 fats in fatty fish, has been shown to preserve collagen, a fibrous protein that keeps skin firm. And EPA in combination with the other omega-3 in fish, DHA (docosahexaenoic acid), helps to prevent skin cancer by reducing inflammatory compounds that can promote tumor growth, says Homer S. Black, Ph.D., professor emeritus in the department of dermatology at Baylor College of Medicine in Houston. Aim to eat two servings of fatty fish each week: not only are the omega-3s good for your skin, they´re good for your heart too.