Does a Banana Ruin the Nutritional Value of Your Smoothie?

You Should Know: A viral nutrition debate has people side-eyeing their smoothies. The claim: bananas contain an enzyme called polyphenol oxidase (PPO) that breaks down flavanols — beneficial plant compounds found in berries and other foods like cocoa, grapes, and tea. The controversy stems from a 2023 study showing that a banana-based smoothie led to lower flavanol absorption compared to a smoothie made without banana.

Going Deeper: The study is real, but the internet may have run too far with the findings. While PPO does appear to reduce flavanol availability, bananas don’t “cancel out” the nutritional value of other fruits. Everything in your smoothie still provides fiber, vitamins, and minerals. Nutrition experts tend to agree that the great banana debate is splitting hairs for most of us. In general, most people don’t need to worry about flavanol absorption — it’s more important to eat enough fruits, vegetables, and fiber in the first place.

Takeaway: If maximizing flavanol absorption is your goal, you may want to pair berries with lower-PPO fruits like mangoes, oranges, or pineapple. But a smoothie with banana is still a nutritious choice.

Bottom Line: Bananas may slightly reduce absorption of one group of beneficial compounds, but they don’t turn a healthy smoothie into an unhealthy one.