Bananas May Reduce Flavonol Absorption in Berry Smoothies, Study Finds
Recent research conducted by the University of California, Davis (UCD) indicates that adding a banana to a berry smoothie could lower the absorption of beneficial flavonols. These compounds, found in plant-based foods like berries, tea, cocoa, and certain fruits, are known for their potential health benefits, including improved cardiovascular and cognitive functions.
The study, published in the journal Food and Function in 2023, involved a controlled, blinded experiment with eight participants. They were given either a flavonol-rich berry smoothie or a simple flavonol capsule. Results showed an increase in flavonol metabolites in the blood of participants.
However, when participants consumed a banana-berry smoothie, researchers observed an 84% reduction in these metabolites compared to a pure flavonol dose. Nutritionist Javier Ottaviani from UCD expressed surprise at how a single banana could significantly decrease flavonol absorption.
The reduction is believed to be due to the enzyme polyphenol oxidase (PPO), which is present in bananas and is involved in the oxidation process that browns the fruit. PPO appears to 'mop up' the antioxidants, preventing them from being effectively absorbed into the bloodstream.
Further experiments showed that when a banana-berry smoothie was left at room temperature, it retained fewer flavonols than a pure berry smoothie after an hour. When PPO was inhibited, flavonols remained more stable.
To explore if bananas could also affect flavonol absorption in the stomach, researchers had 11 participants consume separate banana and berry drinks simultaneously. Even then, flavonol metabolites were less present in the bloodstream than when consuming a berry smoothie alone.
The study's findings are based on a small sample size, and further research is suggested. Nonetheless, the study emphasizes the importance of considering how food preparation and combinations might impact the nutritional benefits of plant-based diets.
