Think your banana smoothie is healthy? New research shows bananas can block the absorption of vital flavanols from berries. Learn why and discover the best fruit combinations.
Smoothies are generally viewed as a healthy option as they are fast to prepare, delicious, and rich in fruits and vegetables. However, recent research shows that not all fruit combinations are equally beneficial when it comes to nutrition. In fact, adding a banana to your smoothie might significantly lower how much of certain important nutrients your body can actually absorb.
When the Chemistry of Fruits Affects Nutrition
Researchers from the University of California, Davis, found that the mix of fruits in a smoothie can impact how well the body absorbs flavanols. These compounds are found in foods like apples, grapes, cocoa, and berries and known to support heart and brain health, and may improve blood flow and reduce inflammation.
The research, published in the journal Food and Function, looked at an enzyme called polyphenol oxidase (PPO). This enzyme is naturally present in many fruits and vegetables and causes fruit to turn brown when exposed to air, like when you cut an apple or peel a banana.
Related Articles
The scientists wanted to know: could this same enzyme also interfere with the flavanols in smoothies and stop the body from absorbing them properly?
The Smoothie Study
To find out, the researchers asked volunteers to drink two different smoothies. One included bananas, which are high in PPO activity, and the other was made with mixed berries, which contain low PPO activity. For comparison, some participants also took a capsule with a known amount of flavanols.
After drinking the smoothies, the team measured how much flavanol ended up in the participants’ blood and urine. The results were surprising. People who drank the banana smoothie had 84% lower flavanol levels than those who took the capsule. In other words, the banana seemed to reduce most of the health benefits of the flavanol-rich ingredients.
Why Flavanols Are Important
Flavanols are a type of plant compound called polyphenols found in foods like cocoa, apples, grapes, and berries. Studies show they help support heart function, improve memory, and reduce inflammation.
In 2022, the Academy of Nutrition and Dietetics recommended that adults consume about 400 to 600 milligrams of flavanols daily to support heart and metabolic health. Many people aim to meet this target through smoothies or fruit-based snacks, making this new finding especially relevant.
The Best Fruits to Use in Smoothies
If you love making smoothies, there’s no need to stop. The key is to choose the right combinations. Dr Ottaviani suggests pairing flavanol-rich fruits, like berries, apples, grapes, or cocoa powder, with ingredients that have low PPO activity, such as pineapple, oranges, mangoes, or yogurt. These options help preserve the beneficial compounds and allow your body to absorb them more effectively.
Bananas are still a good source of nutrients like potassium and fibre, but they may be best enjoyed on their own or in smoothies that don’t include flavanol-rich ingredients. Other foods with high PPO activity, like beet greens, might have a similar effect.
So, next time you’re making your morning smoothie, think carefully before adding a banana. It’s not about avoiding bananas entirely, they are still nutritious, but if you want to get the most out of flavanol-rich foods like berries or cocoa, it might be best to leave the banana out of the mix.
