Do bananas cancel out blueberries?: The Surprising Truth About Your Favorite Smoothie

October 4, 2025 •

4 min read

According to a 2023 study from UC Davis and the University of Reading, blending bananas with blueberries can lead to an 84% reduction in the body's absorption of beneficial flavanols. The shocking discovery sheds new light on the question, 'Do bananas cancel out blueberries?' in your favorite breakfast smoothie.

Quick Summary

A common banana-and-blueberry smoothie can reduce the absorption of heart-healthy flavanols from berries, a small study found. This occurs because an enzyme in bananas, polyphenol oxidase (PPO), breaks down the compounds when blended. This effect is not a major concern for overall nutrition, but separating consumption can maximize flavanol intake.

Key Points

Polyphenol Oxidase (PPO) is the culprit: Bananas contain an enzyme called PPO that, when blended, rapidly oxidizes and breaks down the flavanol antioxidants in blueberries.
Absorption is significantly reduced: A study showed that blending bananas with berries can lead to an 84% reduction in the body's absorption of flavanols from the berries.
Context is key—blending matters: This flavanol reduction is primarily an issue with blended smoothies and less of a concern when the fruits are eaten whole.
The combination isn't 'unhealthy': A banana-blueberry smoothie still provides valuable nutrients like fiber, potassium, and vitamins; it simply reduces the bioavailability of one specific antioxidant compound.
Alternatives are available: To maximize flavanol intake in smoothies, pair blueberries with low-PPO fruits like pineapple, mango, or citrus.
Separate consumption is an easy fix: If you want the full benefits of both, simply eat the bananas and blueberries separately.

Unpacking the Science Behind the Fruitful Feud

The idea that bananas could negate the health benefits of blueberries sounds like nutritional heresy to anyone who enjoys a fruit smoothie. For years, the combination has been a staple, lauded for its balanced flavor and creamy texture. However, recent scientific research has shed a new, intriguing light on this popular pairing. A small, but widely reported, 2023 study highlighted how a naturally occurring enzyme in bananas, polyphenol oxidase (PPO), can significantly diminish the levels of heart-healthy flavanols absorbed from berries when they are blended together.

The Role of Polyphenol Oxidase (PPO)

Polyphenol oxidase is an enzyme responsible for the browning of fruits like bananas and apples when they are cut and exposed to air. It oxidizes phenolic compounds, causing them to turn brown. Blueberries are rich in specific phenolic compounds called flavanols, a class of antioxidants known for their benefits to heart and cognitive health. When you blend bananas and blueberries, the high PPO activity from the banana is released and comes into direct contact with the flavanols from the blueberries. This rapid oxidation process breaks down the flavanols, making them less available for your body to absorb. The study, conducted by researchers at UC Davis and the University of Reading, specifically observed that participants who drank a banana-berry smoothie absorbed 84% fewer flavanols compared to those who consumed the berries alone or via a supplement.

Blending vs. Eating Whole: A Critical Difference

It is important to note that this enzymatic interaction is most relevant when the fruits are blended or puréed, a process that maximizes the surface area of both fruits and ensures the enzymes and flavanols mix thoroughly. When you eat a banana and blueberries whole and separately, the effect is likely minimal to non-existent. The context of consumption is key here. The digestive system is much different from a blender, and the chemical reactions that occur so rapidly when blended are far less likely to happen with the same intensity during natural digestion. For those who enjoy a daily banana-and-blueberry smoothie, the reduction in flavanol absorption is a genuine, research-backed finding. However, for those who simply eat the fruits as part of a varied diet, there is no cause for concern.

A Balanced Perspective: Don't Dismiss the Nutrients

While the study's finding is noteworthy for those seeking to maximize flavanol intake, it's crucial to maintain a balanced perspective. A banana-and-blueberry smoothie does not become a "bad" or "unhealthy" food because of this interaction. Both fruits are packed with essential nutrients, and the smoothie still provides a wealth of benefits:

Fiber: Both fruits are excellent sources of dietary fiber, which is crucial for digestive health.
Vitamins and Minerals: Bananas are rich in potassium and Vitamin B6, while blueberries provide Vitamin K and C.
Convenience: As a quick and easy breakfast or snack, a smoothie remains a far better choice than many processed alternatives.

Alternatives and Practical Tips

If maximizing flavanol absorption is a primary goal, smoothie enthusiasts can easily adapt their recipes. Opting for fruits with low PPO activity can preserve the integrity of the blueberries' flavanols. For those who still love the classic combination, a simple solution is to eat the fruits separately or at different times of the day.

Here are some alternative smoothie ingredient combinations to preserve flavanols:

Berries with pineapple, oranges, or mangoes
Berries with yogurt or kefir
Consider adding spices like cinnamon, which may help inhibit the PPO enzyme

Comparison of Bananas and Blueberries


Nutrient	Bananas	Blueberries	Note
Potassium	High	Low	Essential for blood pressure and heart health.
Vitamin B6	High	Low	Important for brain health and metabolism.
Polyphenol Oxidase (PPO)	High	Low	Enzyme responsible for breaking down flavanols when blended.
Flavanols	Low	High	Powerful antioxidants with heart and cognitive benefits.
Vitamin K	Low	High	Crucial for blood clotting and bone health.
Sugar	High (mostly fructose)	Low	Bananas have more sugar than blueberries.

Conclusion: A Minor Caveat in a Healthy Diet

So, do bananas cancel out blueberries? The answer, like most things in nutrition, is nuanced. The blending of the two fruits can significantly reduce the bioavailability of flavanols from the berries due to the PPO enzyme in bananas. However, this does not render the combination unhealthy or devoid of nutrients. The smoothie still delivers fiber, vitamins, and minerals from both fruits. The key takeaway is to manage your expectations: if maximizing flavanol intake is a top priority, consider consuming bananas and berries separately or pairing berries with low-PPO fruits in your blender. For most people, a mixed fruit smoothie remains a convenient and nutritious dietary choice. The most important thing for overall health is to consistently eat a wide variety of fruits and vegetables.

A deeper dive into the science

For those interested in the primary research, you can explore the full study in the journal Food and Function.

Frequently Asked Questions

No, it is not unhealthy to put bananas and blueberries in a smoothie. Both fruits are still excellent sources of fiber, vitamins, and minerals. The issue is that blending them can reduce the amount of a specific antioxidant, flavanols, that your body absorbs from the blueberries.

Polyphenol oxidase (PPO) is an enzyme naturally present in bananas and other fruits that causes browning when they are cut and exposed to air. When blended with blueberries, the PPO oxidizes and degrades the flavanols in the berries, reducing their bioavailability.

No, eating whole bananas and blueberries together is unlikely to have the same effect. The significant flavanol reduction primarily occurs in blended drinks, where the mixing process maximizes the enzyme's contact with the berry compounds.

Flavanols are a group of powerful plant-based antioxidants found in foods like blueberries, apples, and cocoa. They are associated with several health benefits, including supporting heart and cognitive health.

To maximize flavanol intake in a smoothie, you can blend blueberries with fruits that are low in polyphenol oxidase (PPO), such as pineapple, oranges, and mango.

There is no need to stop eating bananas in your smoothies. If your goal is to maximize flavanol absorption, you can simply consume them separately. Bananas provide valuable nutrients and creaminess to smoothies, and the interaction is not a major nutritional concern in the context of an overall healthy diet.

Yes, eating bananas and blueberries at the same meal but not blended is perfectly fine. The chemical interaction is less likely to happen with the same intensity during natural digestion, so you will still absorb the benefits of both fruits.