Tuna Oil & Cranberry Extract added. Cranberries are a great source of the antioxidant vitamins C and E, dietary fiber, vitamin K, and manganese. They also provide a natural source of polyphenols and proanthocyanins, which play a role in supporting urinary tract health. Natural Kitty Functional Creamy Treats is the best daily reward for your cats. You can feed your cats everyday with Natural Kitty as a reward or treat or feed as a light meal, or serve as main meal complementary.