Can bananas change the nutritional value of your smoothie?
Bananas have long been considered one of the healthiest fruits you can eat. They’re packed with potassium, fiber, vitamin B6, and other nutrients, making them a staple in countless smoothies.
But a recent study raised an interesting question:
Could adding a banana to a berry smoothie actually reduce your body’s absorption of certain beneficial plant compounds?
The answer is more nuanced than many headlines suggested.
In this episode of Causes or Cures, I sat down with Professor Gunter Kuhnle, Professor of Nutrition and Food Science, to discuss his research, what it actually found, and why interpreting nutrition studies is rarely as straightforward as it seems.
Listen to the full episode here: Do Bananas Make Your Smoothie Less Healthy?
What are flavan-3-ols?
Flavan-3-ols are naturally occurring compounds found in foods including:
*Berries
*Apples
*Cocoa
*Tea
*Grapes
Researchers have linked these compounds to potential benefits for cardiovascular health, cognitive function, and overall health. Like many nutrition topics, however, scientists are still working to understand exactly how these compounds work and how much our bodies absorb from different foods.
Why were bananas being studied?
The research focused on an enzyme naturally found in bananas called polyphenol oxidase (PPO).
Polyphenol oxidase helps fruits brown after they’re cut or bruised, but researchers wondered whether it might also reduce the availability of flavan-3-ols when bananas are blended together with flavanol-rich foods.
The study compared participants who consumed a banana smoothie with those who drank a berry smoothie rich in flavan-3-ols.
The researchers found that participants who drank the banana smoothie showed lower absorption of flavan-3-ols than those who consumed the berry smoothie.
Does this mean bananas are unhealthy?
Not at all.
One of the biggest takeaways from our conversation is that this study is not an indictment of bananas.
Bananas remain a nutritious food with many well-established health benefits.
Instead, the study suggests that food combinations may sometimes influence how well we absorb certain compounds—a reminder that nutrition isn’t always about individual foods in isolation.
Nutrition research is more complicated than it looks
One of my favorite parts of this conversation had nothing to do with bananas.
Professor Kuhnle discusses something that’s central to his work: why nutrition research is incredibly difficult to conduct and interpret.
Unlike drug trials, researchers can’t completely control what people eat over months or years. Measuring dietary intake accurately is challenging, people remember foods imperfectly, report inaccurately, and countless lifestyle factors can influence health outcomes.
That’s one reason nutrition headlines often seem to contradict one another.
A single study rarely tells the whole story.
Understanding how nutrition science works, and its limitations, is just as important as understanding the results themselves.
Should you stop putting bananas in smoothies?
I mean, not entirely. Banana smoothies are delicious. Heck, I love bananas. ;)
BUT…if your primary goal is maximizing flavan-3-ol intake from berries or cocoa, this research suggests that you shouldn’t combine them with bananas.
I’m sure there are great banana smoothie recipes out there that don’t involve berries…
Listen to the full conversation
Specifically, in this episode, Professor Kuhnle and I discuss:
*What flavan-3-ols are
*The banana smoothie study
*Polyphenol oxidase (PPO)
*Why bananas may reduce flavan-3-ol absorption
*Whether other fruits have similar effects
*The challenges of measuring diet and nutrition
*Why nutrition studies are often misunderstood
*Practical advice for smoothie lovers
*What this research does—and does not—mean for your health
🎧 Listen to the full episode of Causes or Cures here.
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In case you missed this podcast, Dr. Richard Pratley joined Causes or Cures to discuss why lean muscle mass loss IS a concern when it comes to GLP-1 drugs and rapid weight loss; how muscle differs from lean mass; and best path forward for healthiest weight loss. Tune in Here!