Researchers Discover A Shocking Reason You Might Want To Stop Putting Bananas In Smoothies

Yahoo

08-05-2025

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Nothing hits better than a post-workout smoothie. You might throw in some berries for flavor and bananas to get that nice creamy texture (and potassium). But, according to science, you actually might not want to put these two in the same blend.
A study found that adding a banana to a berry smoothie may actually reduce some of the health benefits you'd otherwise get from the berries. So, what does this mean for you and your smoothies? Here's what you should know, according to experts.
Meet the experts: Scott Keatley, R.D., co-owner of Keatley Medical Nutrition Therapy; Keri Gans, R.D.N., dietitian and host of The Keri Report podcast
The study, which was published in the journal Food and Function, had eight people drink different smoothies: One that contained banana and berries or one with mixed berries. Some were just given a capsule that contained flavanol, a natural antioxidant. Each participant then gave blood and urine samples to measure the amount of flavanols that made it through their body.
The researchers found that when bananas were included in a smoothie, the participants absorbed 84 percent less flavanol.
Flavanol is a natural compound that supports good health. 'Flavanol is a type of flavonoid, a class of natural compounds found in fruits, vegetables, tea, and cocoa,' says Scott Keatley, R.D., co-owner of Keatley Medical Nutrition Therapy.
Flavanols are usually found in fruits like berries, apples, and grapes, Keatley says.
Flavanols have 'strong antioxidant properties,' Keatley says. This means they help to protect the body from damage by free radicals, which are unstable molecules that can damage cells and potentially increase your risk of developing certain diseases and cancer.
Research has also found that flavanols in your diet can help support good brain health and cognition.
It comes down to something called polyphenol oxidase, explains Keri Gans, RDN, host of The Keri Report podcast. This is the enzyme that's thought to make bananas turn brown when they're exposed to air—and they also seem to interfere with flavanol absorption.
But Gans says this doesn't mean you should ditch bananas in smoothies altogether. 'While bananas may reduce the absorption of flavanols due to their polyphenol oxidase content, they still offer valuable nutrients like vitamin C, a powerful antioxidant, plus potassium to help regulate blood pressure and fiber to support digestive health,' she says.
A lot, actually. 'Fruits with a lower polyphenol oxidase include citrus fruits, mango, pineapple, and berries,' Gans says.
But she just recommends focusing on creating a healthy smoothie overall. 'Focus on low added sugar, protein, and healthy fats for fullness, and fruit or veggies for fiber and other beneficial nutrients,' she says.
If you really want to max out your berries' impact, maybe just have eat them with other ingredients. But Gans says there's no need to get too stressed about this. 'If you enjoy a banana, still include a banana,' she says.
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