Key Takeaways
- Bananas and berries might not be the best smoothie combination for maximizing flavanol consumption, according to a new study.
- An enzyme in bananas makes flavanols less bioavailable when it's combined with berries.
- Researchers say bananas are still a great fruit to be eaten on the side, or added to smoothies that don't have flavanol-rich ingredients such as berries, grapes and cocoa.
Bananas make smoothies sweet and creamy, but a new study suggests that blending bananas with berries might not be the best combination for maximizing flavanol intake.
Berries are a good source of flavan-3-ol, a subtype of flavanoid that offers a wide range of health benefits. However, a small study published in the journal Food & Function found that the level of flavanols in smoothies decreases when flavonol-rich foods are blended with bananas.
This study got a lot of attention after a viral TikTok video explaining the research claimed that adding bananas to berry smoothies will “destroy their nutritional value.” The video has since sparked an intense debate on whether bananas have a place in fruit smoothies.
Javier Ottaviani, PhD, the lead author for the study and an adjunct researcher at UC Davis, said the combination of bananas and berries isn’t the best for people focused on certain nutritional goals.
“If consumers want to increase their flavanol intake via fruit smoothies, it’s best to avoid combining flavanol-containing foods, like berries, with fruits and vegetables that contain a high level of polyphenol oxidase, like bananas,” Ottaviani told Verywell in an email.
A reaction between flavanols in berries and an enzyme in bananas called polyphenol oxidase (PPO) is to blame. PPO is the same enzyme that causes fruits to brown when it’s exposed to oxygen—think about apple slices that have been left out for a few minutes.
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Why Might Bananas Reduce Flavanols in Berry Smoothies?
As declared in the conflict of interest, Ottaviani and other members of the research team are employed by Mars, which has “long-term research and commercial interests in flavan-3-ols.”
This relatively small study only included eight healthy male participants between the ages of 25–60. Participants drank a banana-based smoothie, a mixed berry smoothie, and took a flavan-3-ol supplement as a control. Blood tests showed that the flavan-3-ol content after the mixed berry smoothie was similar to the control level, but the flavan-3-ol content was 84% lower after the banana smoothie.
“While it will be nice seeing that these results are repeated in a larger population, we believe that the results obtained are generalizable and coherent with current scientific literature on this topic,” Ottaviani said.
The study showed that PPO in bananas makes the flavanols in berries less bioavailable, which essentially means there’s less that your body could absorb, according to Caroline West Passerrello, EdD, RDN, LDN, a community coordinator and instructor at the dietitian nutritionist program at the University of Pittsburgh.
“However, keep in mind that the bioavailability of flavanols are fairly low (2–20% when consuming a flavanol-rich food), so don’t overthink it when incorporating them into your diet,” Passerrello told Verywell in an email. “However, if you want the most benefit, try to eat flavanols in the absence of any ripe or overripe produce.”
Passerrello said there is more research to be done and the findings from this study are just one piece of the puzzle when it comes to understanding how the body processes food.
“This is one isolated study on a small sample size. Digestion, absorption, and metabolism of nutrients vary from person to person and can change over time in the same person. Therefore, I suggest we consider this as one piece of information when making recommendations, continue to study these effects on larger sample sizes, and not make sweeping dietary guideline changes based on this one study,” she said.
Polyphenols Benefits and Foods to Eat
What Else Can You Use Other Than Bananas?
Flavanols are having a moment in the nutrition spotlight. The Academy of Nutrition and Dietetics issued guidelines last year recommending that people consume 400–600 milligrams offlavan-3-ols each day from foods like raspberries, blackberries, apples, and green or black tea.
If you want to maximize flavanol intake from your smoothies, you can consider using foods with lower PPO, such as pineapple, oranges, mango, and yogurt, Ottaviani said. In addition to flavanols, berries contain a good source of vitamins, fiber, and antioxidants.
However, if you enjoy having bananas in your smoothie, you don’t necessarily have to let go of this recipe, according to Passerrello.
“If you’re generally healthy and consuming a well-balanced diet with a variety of fruits and vegetables throughout the day and occasionally consuming these mixed fruit smoothies, I would not be concerned about the potential impact of polyphenol oxidase on the flavanol absorption,” Passerrello said.
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What This Means For You
Most Americans don’t eat enough fruits and vegetables. Experts say it’s better to focus on adding more produce to your diet instead of worrying about making the best possible smoothie recipe.
4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Ottaviani JI, Ensunsa JL, Fong RY, et al. Impact of polyphenol oxidase on the bioavailability of flavan-3-ols in fruit smoothies: a controlled, single blinded, cross-over study. Food Funct. 2023;14(18):8217-8228. doi:10.1039/d3fo01599h
Moon KM, Kwon EB, Lee B, Kim CY. Recent trends in controlling the enzymatic browning of fruit and vegetable products. Molecules. 2020;25(12):2754. doi:10.3390/molecules25122754
Crowe-White KM, Evans LW, Kuhnle GGC, et al. Flavan-3-ols and cardiometabolic health: first ever dietary bioactive guideline.Adv Nutr. 2022;13(6):2070-2083. doi:10.1093/advances/nmac105
Johns Hopkins Medicine. Berry good for your heart.
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By Stephanie Brown
Brown is a nutrition writer who received her Didactic Program in Dietetics certification from the University of Tennessee at Knoxville. Previously, she worked as a nutrition educator and culinary instructor in New York City.
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