Blueberries are a source of dietary fibre, with highest antioxidant activity, which can neutralize free radicals that can cause cancer, cardiovascular disease, and Alzheimer's disease. They are a good source of antioxidants, retards aging, reduce cell damage (cause of cancer), cardiovascular disease, loss of brain function. Blueberries contain tannins, which prevents urinary tract infections. Additionally, contain anthocyanins (blue pigment in blueberries), which reduces eyestrain. Blueberries are excellent sources of vitamin C, beneficial to eyesight and memory, and good sources of dietary fibre. They are an excellent source of manganese, which aids development of bones and metabolism of protein, carb, and fat.