Blueberry or strawberry, their role in prevention of heart attack

In the recent study published in Prevention advocates that blueberries or strawberries in yogurt , three time per week lower the risk of heart attack by three times.
In one of the study where who took more than three servings of strawberries or blueberries per week had 32 % less heart attack.
The berries has anthocyanin and flavonoids which considered as giving flexibility to the vessels. This will lower the blood pressure.
Eric Rimm advised to take three 1/2 cup servings of fresh or frozen berries per week as a preventive measure.