This Common Ingredient Could Cancel Out Some of Your Smoothie’s Health Benefits

The whole point of having a fruit smoothie is to infuse nutrition into your day in a drink that goes down easily. But while bananas and berries are a common combination, new research suggests that those bananas may be secretly sabotaging some of the health benefits in your smoothie.

For the Food and Function study, researchers had eight healthy volunteers drink two different smoothies. One smoothie contained bananas and berries, while the other just had mixed berries. They were also given a capsule that contained the natural antioxidant flavanol, which is common in berries. After having the smoothies or capsule, the participants gave blood and urine samples that the researchers used to measure the levels of flavanols in their body.

The researchers discovered that people who drank the banana smoothie had 84% lower flavanol levels compared to when they just took a flavanol capsule, suggesting that they absorbed less of the antioxidant in their drink. They also absorbed less with the banana smoothie compared to the all-berry smoothie.

While that sounds like bad news for banana smoothies, dietitians say there are a few things to keep in mind before tossing the bunch sitting on your counter.

What’s the potential concern here?

Before we get into why this happens, it’s important to recap why you should care about flavanols in the first place. These antioxidants are found in certain foods like apples, pears, berries, grapes, and cocoa, Jessica Cording, RD, CDN, author of The Little Book of Game-Changers, tells SELF.

They’re strong antioxidants, which means they help to protect your body from damage from free radicals—unstable molecules that can damage cells and raise your risk of developing certain diseases, including cancer, Cording explains. Research also suggests that having a diet rich in flavanols can help support good brain health and lower your risk of heart disease. So, having flavanols in your diet—and actually absorbing them—is a good thing.

Yes, bananas can reduce flavanol content.

This isn’t unique to bananas, though. “There are a variety of foods that have specific enzymes or other compounds in them that impact the absorption of some nutrients,” Cording says.

Bananas contain something called polyphenol oxidase, which seems to impact the absorption of flavanols in your body. (Polyphenol oxidase is also what makes bananas turn brown over time.)

“But bananas aren’t necessarily the only food you might run into an issue like this,” Cording says. “Sometimes, certain nutrients and foods may interfere with the absorption of other nutrients.”

What’s the takeaway?

Dietitians want you to keep a few things in mind. For starters, this was a small study that only contained eight people. The study also just looked at men, making it hard to say if the findings would apply to women as well.