Surprising research reveals why you shouldn't add bananas to your smoothies

New research from the University of California, Davis reveals that adding bananas to berry smoothies can significantly reduce the body’s absorption of flavanols, key plant compounds linked to heart and cognitive health. The study found that the enzyme polyphenol oxidase (PPO), which is abundant in bananas, plays a central role in this effect. When blended into smoothies, the high PPO activity in bananas triggers chemical reactions that diminish the availability of flavanols from berries and other ingredients. In controlled tests, participants consumed smoothies made with either bananas or mixed berries, alongside a flavanol capsule as a control. Blood and urine analyses showed that flavanol levels were 84% lower after drinking the banana smoothie compared to the capsule, while the berry smoothie maintained flavanol levels similar to the control. This suggests that the presence of PPO in bananas interferes with the body’s ability to absorb these beneficial compounds, despite the fruit itself being healthy. Polyphenol oxidase is known for causing browning in cut or bruised fruits, but this study highlights its less understood impact on nutrient bioavailability. The findings emphasize how common food combinations and preparation methods can alter the nutritional benefits of meals and beverages. Given the popularity of banana-berry smoothies as a healthful choice, this research may prompt consumers and nutritionists to reconsider ingredient pairings to maximize nutrient intake. The study, published in the journal Food & Function, underscores the importance of understanding food interactions beyond individual nutrient content. It opens new avenues for exploring how enzymes like PPO affect the health properties of mixed foods, potentially influencing dietary recommendations and product formulations in the future.