I believe the answer is: Blueberries are only one of many flavonoid-rich foods that may slow cognitive decline, but can contribute to an overall healthy diet high in plant foods.
Like any other fruits, blueberries are high in fiber and vitamin, which would prevent your body form deteriorating too early. One downside of fruits like this is that it typically contain high amount of sugar compared to vegetables. So eating too much of it would not be a good idea.
