Smoothies are a super-convenient option for grabbing healthy nutrients while on the go, but a new study has found that adding a banana could cut the body’s absorption of flavanols by 84%. So, should bananas be banished from your smoothies? It all depends on your goals, says science. Research published in the Royal Society of Chemistry’s Food and Function journal, looking to find the best combination of fruits for your smoothie, found that adding banana significantly decreases the level of heart-healthy flavonoids, leading scientists from the University of California, David, to conclude that blending certain ingredients together can positively, or negatively, influence the health-boosting effects of your beloved smoothie. Apparently, it’s all down to an enzyme called polyphenol oxidase and how it interacts with flavanols, the bio active compounds that benefit the heart and brain. Polyphenol oxidase, or PPO, can be seen when it reacts with the air and turns the fruit’s peel and flesh brown.

“We sought to understand, on a very practical level, how a common food and food preparation like a banana-based smoothie could affect the availability of flavanols to be absorbed after intake,” said the study’s lead author, Javier Ottaviani.

How was the study carried out?

The researchers had participants drink a smoothie made with a banana—naturally high in PPO—and a second smoothie made with mixed berries. Individuals were also provided with a flavonoid capsule for control purposes. Blood and urine samples were then analyzed to determine the presence of flavanols in the body.

What were the results?

The banana’s effects were significant and contributed to an up to 84% lower level of flavonoids in the body. “We were really surprised to see how quickly adding a single banana decreased the level of flavanols in the smoothie and the levels of flavanol absorbed in the body,” said Ottaviani. “This highlights how food preparation and combinations can affect the absorption of dietary compounds in foods.”

So, should bananas be banished from smoothies? It’s a matter of nutritional goals, explained Ottaviani. Banana’s offer a variety of other benefits, including heart-healthy potassium, digestion aiding fiber, and energy boosting carbohydrates and vitamins. But for those who want to use their smoothie to boost flavanols, other options might work better. To choose the right fruit pairing, Ottaviani says reaching the recommended target of 400 to 600 milligrams of flavanols per day, for cardiometabolic health, involves choices like combining flavol-rich fruits such as berries with fruits that are naturally low in PPO, like pineapple, oranges, or mango.