Bananas May Diminish Blueberry Antioxidants, but How Much Should You Care?

During a 2026 episode of the Mel Robbins Podcast, biomedical scientist Dr Rhonda Patrick asserted that the enzyme polyphenol oxidase (PPO) present in bananas breaks down the polyphenols in blueberries, lowering the antioxidant benefit of a banana-blueberry smoothie. She referenced a 2023 study that found participants who consumed banana smoothies with added flavanols showed lower blood levels of those antioxidants compared with mixed-berry smoothies containing the same additive.

The Guardian

The cited research examined how PPO affects flavanols—a subclass of polyphenols—by measuring blood concentrations after participants drank smoothies spiked with flavanol extracts. The study involved only eight subjects, did not actually combine bananas and blueberries, and used cocoa-derived flavanols funded by the Mars company, which also markets flavanol supplements. Blueberries are rich in anthocyanins, the primary polyphenols linked to reduced mortality and cardiovascular risk, whereas the study measured flavanols, which are less central to blueberry nutrition.

The Guardian

Dr Joe Schwarcz, a science communicator at McGill University, highlighted several flaws: the absence of a true banana-blueberry blend, the tiny sample size, and the potential conflict of interest from corporate funding. He acknowledged that PPO can alter polyphenol levels but emphasized that the study did not assess the “important compounds of blueberries.” Alyssa Northrop, a registered dietitian, noted that nutrient interactions are common but cautioned against over-micromanaging food pairings, stressing that most people fall short of the recommended five daily fruit and vegetable servings. Sheri Gaw, a registered dietitian nutritionist, pointed out bananas’ practical benefits—natural sweetness, texture, affordability, and nutrients such as potassium, vitamin B6, vitamin C, manganese, magnesium, and about three grams of fiber per medium fruit.

The Guardian

Given the modest impact of PPO on blueberry anthocyanins, the interplay between bananas and berries is “insignificant” in the context of an overall diet. For those concerned about flavanol intake, experts suggest alternatives like mango or pineapple, or adding thickening agents such as oats, yogurt, silken tofu, kefir, avocado, or frozen cauliflower. Consuming 400–600 mg of flavanols daily from sources like green tea, cocoa, or apples may support cardiometabolic health, but polyphenols are not essential nutrients and lack a defined daily requirement.

The Guardian

• “Nutrient interactions in food are actually quite common,” — Alyssa Northrop

The Guardian

• “Bananas are often added to smoothies for their natural sweetness and unique texture that can make the smoothie thick and creamy,” — Sheri Gaw

The Guardian