When trying to eat healthy foods, think in color. It seems the more intense the color, the more nutrients there are in a natural food. Blackberries can be included in this category. Blackberries provide 28 percent of the daily fiber needed based on a 2000 calorie diet. Blackberries also are a super-source of vitamin C. These power berries provide more than 50 percent of the vitamin C a person needs daily. With only 60 calories a cup, these berries are packed with antioxidants that may help prevent cancer.