If you like to throw different fruits into your blender for your morning smoothie, there’s one you may want to leave out if you want to get the maximum health boost.
Bananas are the one fruit to avoid if you are blending apples, pears, blueberries or blackberries in the smoothie; they negate the flavanol richness of the other fruits.
Scientists have discovered the extraordinary effects a banana can have on flavanol-rich fruits such as mixed berries. In one test, scientists from the University of California at Davis discovered that adding a banana to the berry smoothie lowered flavanol levels by 84 percent.
It’s all to do with the banana’s PPO (polyphenol oxidase) qualities. Cut up a banana and it quickly starts to turn brown, and it’s this activity that reduces flavanol levels of other fruits.
They tested different smoothies for their flavanol levels, which were measured in the blood of the participants, who also ate a flavanol capsule as a comparison. The berry smoothie easily delivered the 400 to 600 mg of flavanols that are recommended we have every day to maintain heart health, but the level dropped significantly when a banana was added to the mix.
Stick to low-PPO fruits such as berries, pineapple, oranges, mango and yogurt, for your flavanol boost, the scientists say.
But that doesn’t mean you shouldn’t put a banana into the blender; just leave out the berries and instead mix it with other PPO fruit and vegetables, such as beet greens. And if you are addicted to your banana smoothie, you can get your flavanols from tea, which is still one of the richest dietary sources, the researchers say.