Banana smoothie, the sweet and delicious beverage, is a breakfast staple for many. Quick and easy to make, they are an excellent way for a quick energy boost and to improve digestion. However, experts feel adding bananas to your smoothie might be more harmful than healthy as they hinder the body's absorption of flavonols, plant-based compounds known for their antioxidant properties. A new study published in the Journal Food and Function highlights how certain fruits can affect nutrient absorption in the body. Here's all you need to know.
Many people mix a variety of fruits to their smoothies to power up their day. However, mixing flavanol-rich berries with bananas, rich in naturally occurring enzyme, polyphenol oxidase, could hinder the absorption of the beneficial flavan-3-ols, a subclass of flavanols. How to know which fruit has high polyphenol oxidase? The enzyme could lead to browning of fruits when cut or bruised, and is found in many fruits and vegetables but is especially found abundantly in bananas.
The researchers found that if you are aiming to reap the benefits of flavanols, banana isn't the fruit that will help you as the absorption of the plant compound could reduce by a striking 84%. For comparison, participants who took a flavanol capsule absorbed significantly more of these beneficial compounds.


Now flavanols are quite important for your health as they support your cardiovascular and cognitive health, which makes them crucial especially for elderly.
Flavanols are natural compounds known to support heart and brain health. The Academy of Nutrition and Dietetics recommends a daily intake of 400–600 milligrams. A lack of flavanols, especially in older adults, has been linked to cognitive decline and poor cardiovascular function.
What the study found

The participants were divided into groups and were given smoothies containing bananas, and those with low PPO fruits like mixed berries. They were also given flavanol capsules. After that their blood was drawn to understand how it impacted the flavanol absorption . The researchers were surprised to note that bananas in the smoothies may be doing more harm than good.
Drinking banana smoothie ended up reducing the flavanols in the body by a shocking 84% compared to the group that had the capsules or the berry smoothie. The experts explained that PPO interacts with flavanols, causing them to degrade and block them from entering the bloodstream.


Having flavanols separately from the banana smoothie also didn't affect the absorption positively.
“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.
Key fruits high in Polyphenol Oxidase (PPO)
Apples, pears, avocados, plums and peaches, grapes (especially red or Concord), are high in PPO and must be avoided in smoothies when the aim is to increase the levels of flavanols.