A claim made by biomedical scientist Dr Rhonda Patrick on the Mel Robbins Podcast suggested that adding banana to a blueberry smoothie could negatively affect the berries' nutritional benefits. Dr Patrick stated that polyphenol oxidase, an enzyme found in bananas, breaks down polyphenols present in blueberries, potentially reducing their benefits.
The claim likely stems from a 2023 study that investigated how polyphenol oxidase impacted the body's absorption of flavanols, a type of polyphenol. This study observed that participants consuming banana smoothies with added flavanol had lower blood levels of these antioxidants compared to those who drank mixed-berry smoothies with the same additive.
However, Dr Joe Schwarcz, a science communicator at McGill University, noted that the 2023 study did not combine bananas and blueberries, had only eight subjects, and was funded by a company that sells flavanol supplements. He also highlighted that anthocyanins, not flavanols, are proportionally more significant in blueberries and are linked to various health benefits.
Registered dietitians suggest that while nutrient interactions are common, focusing on a varied diet with plenty of fruits and vegetables is more important than micromanaging every food combination. Eating too few fruits and vegetables is considered a greater concern than optimising polyphenol absorption from every smoothie.