A viral social media video and subsequent discussions have raised questions about whether bananas, a common smoothie ingredient, might diminish the health benefits of other fruits like blueberries. Biomedical scientist Dr. Rhonda Patrick, founder of FoundMyFitness, cited recent research suggesting that bananas contain an enzyme called polyphenol oxidase (PPO) which can break down polyphenols—beneficial compounds found in fruits like blueberries that support gut, heart, and brain health. PPO is also responsible for the browning of cut fruit.
Patrick referenced a 2023 study published in the journal Food & Function that involved eight healthy men. On separate occasions, participants consumed either a banana smoothie, a mixed berry smoothie, or flavan-3-ol capsules with milk. Blood tests indicated that those who drank the banana smoothie absorbed approximately 84% fewer beneficial plant compounds compared to those who took the flavan-3-ol capsules. Although a banana-blueberry smoothie was not specifically tested, the study's findings suggest that bananas could potentially reduce the absorption of flavan-3-ols from berries.
Patrick stated that while bananas are nutritious and she consumes them, adding them to blueberry smoothies could degrade some of the polyphenols present. She noted that if the goal is to maximize polyphenol preservation from berries, the enzymatic interaction is a factor to consider.
However, registered dietitian nutritionists have offered a more nuanced perspective. Ilana Muhlstein, a registered dietitian nutritionist based in Los Angeles, acknowledged the findings as "interesting" but cautioned against overstating their implications. "It doesn't mean the smoothie loses all of its health benefits," Muhlstein said. "You're still getting fiber from the banana, and many other beneficial nutrients from polyphenol-rich fruits."
Muhlstein also pointed out that the study had a small sample size of eight participants and has not yet been replicated. She further noted that the research used a standardized cocoa-derived flavanol supplement rather than whole fruits, which may be absorbed differently by the body.
Robin DeCicco, a certified holistic nutritionist in New York, agreed that the findings do not necessitate avoiding bananas for everyone. She emphasized that nutrition advice should be individualized and that for many Americans, the priority should be increasing overall intake of nutrient-rich foods like bananas and berries, rather than focusing on complex interactions. "If you're eating a banana instead of french fries, that's good," DeCicco advised. She suggested that for individuals focusing on weight loss or blood sugar balance, opting for lower-sugar, higher-fiber fruits might be beneficial, while others may not need to make such distinctions.
For those aiming to maximize polyphenol intake, Muhlstein suggested alternatives to bananas in smoothies that can provide a similar creamy texture, such as frozen zucchini, avocado, or Greek yogurt.