Are Bananas Secretly Sabotaging Your Smoothie? Here’s What the Science Says

A new study has revealed that adding a banana to your antioxidant-rich smoothie could drastically cut down the benefits you think you’re getting—specifically by blocking the absorption of powerful compounds called flavanols. Here's what you need to know before you blend again.

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Bananas are a go-to ingredient for many smoothie lovers—creamy, naturally sweet, and full of nutrients. But a recent study suggests that this beloved fruit might be undermining one of your smoothie’s biggest health benefits.

If you’re like most smoothie fans, bananas are probably one of your go-to ingredients. They’re creamy, sweet, and make any blend taste better. But what if we told you that your favorite fruit might actually be canceling out some of your smoothie’s biggest health benefits?

A new study published in the journal Food and Function has revealed that bananas could be interfering with your body’s ability to absorb flavanols—those powerful plant compounds found in foods like berries, tea, and cocoa that are linked to better heart and brain health.

Why Bananas Might Ruin Your Smoothie

Researchers from the University of California, Davis, and the University of Reading dug into this by looking at an enzyme called polyphenol oxidase (PPO). It’s naturally found in many fruits and vegetables and is responsible for the browning that happens when they’re cut or bruised. Bananas, it turns out, are packed with PPO.

So what happens when you throw a banana into your berry smoothie? According to the study, it slashed flavanol absorption by a whopping 84%. That’s right—just one banana can almost wipe out the good stuff from your antioxidant-rich berries.

Flavanols are a type of plant-based compound that belong to a larger group called flavonoids—natural antioxidants found in many fruits, vegetables, teas, and even chocolate. They're especially abundant in berries, apples, grapes, tea, and cocoa.

“Smoothies are a popular way to pack fruit and vegetables into our morning routines,” said Professor Gunter Kuhnle, one of the study’s lead authors. “We knew PPO could break down flavanols, but the fact that a single banana had that much of an effect really surprised us.”

Why do flavanols matter? Flavanols help protect your cells and support your heart and brain, which is why scientists and nutritionists often recommend eating foods rich in them.

So what should you do if you’re drinking smoothies for the health benefits?

Don’t worry—you don’t have to ditch your daily blend. Just consider swapping bananas for other smoothie-friendly ingredients that don’t interfere with flavanols. Think pineapple, mango, oranges, or even a scoop of yogurt. These options are still delicious and help you get the most out of those powerful plant compounds.

Bananas are still great on their own (hello, potassium and fiber!), but if you’re loading up on berries to boost your antioxidant intake, maybe save the banana for a mid-morning snack instead.

News Reference:

Impact of polyphenol oxidase on the bioavailability of flavan-3-ols in fruit smoothies: a controlled, single blinded, cross-over study. 2023.Javier I. Ottaviani, Jodi L. Ensunsa, Reedmond Y. Fong, et al.

Study Shows You Should Skip Bananas in Smoothies. May 1, 2025.

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