Bananas Can Make Your Smoothie Less Healthy

Bananas have long enjoyed a reputation as a health food staple. Packed with fiber, potassium, and natural sweetness, they’re a go-to for people looking to boost their daily nutrition. But new research suggests your beloved breakfast smoothie may be less nutritious if you toss a banana into the blender.

According to a study published in the journal Food & Function, bananas may actually reduce the body’s ability to absorb flavanols — antioxidants linked to heart and brain health that are especially abundant in berries and cocoa. The culprit is an enzyme called polyphenol oxidase (PPO), which is naturally present in bananas and is responsible for the fruit turning brown when exposed to air.

PPO breaks down flavanols quickly, which dramatically limits their bioavailability — meaning your body can’t absorb them as effectively.

Researchers found that when a banana was added to a smoothie containing flavanol-rich foods, it slashed flavanol absorption by a staggering 84%.

In other words, you may only be getting about 16% of the antioxidant benefit you expected.

The effect was especially pronounced in smoothies heavy on berries like blueberries, raspberries, or blackberries — fruits prized for their flavanol content. This suggests that while bananas themselves aren’t unhealthy, their interaction with other ingredients could be undermining your efforts to eat (or drink) more antioxidants.

This doesn’t mean bananas should be banished from your diet.

Experts behind the study stress that bananas are still nutritious and offer plenty of benefits on their own. The key takeaway is more about food combinations than demonizing a single ingredient. If you’re reaching for a berry-based smoothie to maximize antioxidants, you might want to hold the banana and enjoy it separately later in the day.

The findings highlight an often-overlooked truth in nutrition: how we combine foods can matter almost as much as what we eat. And for smoothie lovers looking to optimize their health game, it might be time to rethink the fruit lineup.