Bananas Could Be Wrecking Your Smoothie's Superpowers, Study Suggests

Yahoo

20-05-2025

Bananas drastically reduce flavanol absorption in smoothies — by about 84% — due to their high levels of the enzyme polyphenol oxidase (PPO).
Flavanols are important for healthy aging and mental health, with benefits seen especially in women, according to recent studies.
To maximize flavanol intake, blend flavanol-rich fruits like berries with low-PPO ingredients such as pineapple, mango, oranges, or yogurt — and avoid bananas in the mix.The next time you go to make a smoothie, think long and hard about what you add to it.
In May, SciTechDaily highlighted a study published in the journal Food and Function that examined how an enzyme called polyphenol oxidase (PPO) affects the absorption of flavan-3-ols, a subclass of flavanols, in the human body. This enzyme is critical as it causes fruits to turn brown, including bananas and apples. Flavanols are equally important for human health, as they help improve our overall well-being and can aid in aging gracefully.
As Food & Wine recently explained, a 2025 study in the American Journal of Clinical Nutrition showed that individuals who consumed higher quantities of flavanols had a lower risk of frailty and a decreased risk of poor mental health as they age. The findings were more pronounced in women; however, men also experienced a net positive benefit.
And because smoothies have long been a popular choice for health-conscious individuals seeking to consume a variety of fruits and vegetables, the researchers of the study aimed to test how different fruit combinations affect the absorption of key nutrients.
Related: This Inexpensive Fruit Can Help Lower Your Blood Pressure Naturally, Study Suggests
To investigate this, researchers recruited volunteers who were tasked with consuming smoothies with high PPO activity, including those containing bananas, and smoothies with low PPO fruits, such as mixed berries. Participants also took flavanol supplements in capsules to serve as a control. They then had their blood drawn to measure the difference. According to the findings, bananas may be doing more harm than good in that smoothie mix.
The findings noted that drinking the banana smoothie drastically reduced the amount of flavonols the body absorbed, and not just by a little. It reduced absorption by about 84% compared to the groups that had the capsules or the berry smoothie. The reason, the team explained, is that PPO interacts with flavanols quickly, causing them to degrade and preventing them from entering your bloodstream.
Perhaps most surprisingly, even when participants consumed flavanols separately from the banana smoothie (taking alternating sips of the berry smoothie) absorption was still negatively impacted.
As for what you can take away from this study, it's that fruits like berries remain an excellent choice for your next blended drink. Perhaps you could simply enjoy that banana on its own as a snack later.
Related: A Banana That Won't Brown So Fast? Scientists Just Made It Happen
'Smoothies are a popular way to pack fruit and vegetables into our morning routines. We know from previous studies that flavanols can be broken down by polyphenol oxidase. The extent of the effect from adding a single banana was still very surprising — it had enough polyphenol oxidase to destroy the vast majority of flavanols found in the berries," Gunter Kuhnle, a professor of nutrition and food science at the University of Reading and co-investigator of the study, said in a statement.Want to punch up the flavanols even more? Kuhnle had the answer. 'If you want to boost your flavanol intake with a smoothie, you should combine flavanol-rich fruits like berries with foods that have a low polyphenol oxidase activity like pineapple, oranges, mango, or yogurt.'
Read the original article on Food & Wine