Bananas Reduce Flavanol Absorption in Berry Smoothies

Adding bananas to berry smoothies can significantly decrease the body's ability to absorb healthy flavanols, according to new research. This discovery highlights how specific food combinations can alter the nutritional benefits received from meals. The study, conducted by researchers at the University of California, Davis, was published in the Royal Society of Chemistry journal *Food & Function*.

Flavanols are natural plant compounds linked to improved heart and cognitive health. They are present in foods such as apples, pears, blueberries, blackberries, grapes, and cocoa. The reduction in flavanol absorption is attributed to polyphenol oxidase (PPO), an enzyme found in high concentrations in bananas.

Javier Ottaviani, director of the Core Laboratory of Mars Edge and an adjunct researcher with the UC Davis Department of Nutrition, led the study. Researchers aimed to understand how common food preparation methods, like making a banana-based smoothie, affect flavanol availability. PPO is the enzyme responsible for the browning reaction observed when fruits like apples or bananas are cut and exposed to air.

Participants in the study consumed different smoothies and a flavanol capsule. Those who drank a banana-based smoothie showed 84% lower flavanol levels in their blood and urine compared to a control group that consumed a flavanol capsule. In contrast, a mixed berry smoothie, which has low PPO activity, resulted in flavanol levels similar to the control. A second test indicated that PPO activity might continue to affect flavanol absorption even after consumption, possibly in the stomach.

These findings do not suggest that bananas are unhealthy. Bananas provide fiber, potassium, and other essential nutrients. However, when the primary goal is to maximize flavanol intake from berries or other flavanol-rich foods, bananas may not be the best choice. The Academy of Nutrition and Dietetics recommends 400 to 600 milligrams of flavanols per day for cardiometabolic health.

For those seeking to boost flavanol intake through smoothies, researchers suggest pairing flavanol-rich fruits with ingredients that have low PPO activity. Examples include pineapple, oranges, mango, or yogurt. Bananas can still be consumed separately or in smoothies where flavanol absorption is not the main objective. This small, controlled study involved eight healthy men in the first part and eleven participants in the second, providing intriguing insights into food interactions.