Blueberries: "Researchers at the USDA Human Nutrition Center (HNRCA) have found that blueberries rank #1 in antioxidant activity when compared to 40 other fresh fruits and vegetables.  Antioxidants help neutralize harmful by-products of metabolism called "free radicals" that can lead to cancer and other age related diseases. Anthocyanin -- the pigment that makes the blueberries blue -- is thought to be responsible for this major health benefit."

Source - Atlanticblueberry.com