Buzz
TikTok is all about banana smoothies. Within minutes of scrolling, you’ll find smoothie recipes, freezing tips (peel them first!), and endless videos of people blending bananas and other fruits in their kitchen while showing off their abs. But now there’s a new wave of content cautioning us to never add bananas to smoothies, claiming they destroy the nutritional value.
Let’s set the record straight on that smoothie advice you’ve seen on TikTok
Since when did bananas ruin smoothies? Apparently, it started in August. A study in the journal Food & Function revealed that bananas may lower the bioavailability of flavon-3-ols in smoothies.
The study is legitimate, and many TikToks about it have shared the findings accurately. The mistake lies in their conclusion that bananas shouldn’t be added to smoothies. That’s not what the researchers determined, and there’s no need to cut bananas from your smoothies.
The press release that introduced the study likely sparked this confusion (it calls adding a banana to a smoothie a 'mistake'), but it also points out that the lead author of the study, Javier Ottaviani, 'stated that bananas are still a fantastic fruit to enjoy in smoothies.' So clearly, the warnings about bananas are overblown.
What the study actually revealed
The study wasn’t about the general nutritional value of bananas or smoothies. It focused on a specific biochemical question: Does an enzyme in bananas interact with a particular type of antioxidant in cocoa extract?
Antioxidants are a wide-ranging group of chemicals. Vitamin C is an antioxidant, but so are lycopene and resveratrol (compounds well-known in tomatoes and grapes), as well as anthocyanins, the red and blue pigments found in berries. The antioxidant studied here, however, is not any of the above, but a different one found in tea and cocoa. It’s called (-)-epicatechin, part of the flavon-3-ols antioxidant family.
In the study, eight healthy men from the UC Davis campus participated in various experiments with different test items on different days:
A smoothie made with bananas, almond milk, and a cocoa extract containing epicatechin.
A smoothie containing the same cocoa extract, along with strawberries, blueberries, blackberries, raspberries, almond milk, water, crushed ice, and yogurt (likely for texture purposes).
A glass of milk paired with a capsule containing the cocoa extract.
Bananas contain an enzyme called polyphenol oxidase (PPO), and the researchers sought to determine whether this enzyme in bananas could influence the levels of (-)-epicatechin, one of the flavon-3-ols, when consumed in smoothies.
Surprisingly, the answer was yes! Our bodies convert epicatechins into other chemicals within the same family, and the researchers collected blood samples from the volunteers after each experiment. After consuming the berry smoothie or the capsule with milk, the blood levels of these chemicals increased. However, after drinking the banana smoothie, the levels remained unchanged.
This strongly suggests that the PPO in the banana had broken down much of the epicatechins in the cocoa extract. Further experiments in the same study indicated that this chemical reaction likely occurs both when the ingredients are combined in the smoothie and in our stomachs after consumption.
More importantly, here’s what the study did not find
The study did not test a berry smoothie with a banana added. No smoothies were tested that combined berries with bananas.
The study did not measure the levels of antioxidants or other nutrients from berries. They focused specifically on how the antioxidants in the cocoa extract were affected.
The study also didn’t examine any other aspects of nutrition beyond this very specific chemical interaction (PPO from bananas and (-)-epicatechins from cocoa extract).
Therefore, we cannot conclude that adding a banana to a mixed fruit smoothie “destroys” or “ruins” the nutrients or antioxidants from the berries.
Why it’s impossible to truly “destroy” nutrition
If an enzyme in bananas can reduce the bioavailability of certain antioxidants... does it really matter? Were you drinking smoothies to specifically boost your intake of flavon-3-ols? More likely, you were aiming to add some fruit to your diet and/or enjoy a tasty breakfast or drink because you were hungry.
Despite their PPO activity, bananas also offer fiber, which is beneficial for your health, and carbs, which our bodies can use in many ways. A medium banana provides 20% of your daily vitamin B6, 17% of vitamin C, and 8% of magnesium needs.
The recent study didn’t take any of these nutrients away from you. You still get all of the benefits listed above, no matter what happens to the flavon-3-ols in your smoothie.
If you’re genuinely concerned about your flavon-3-ols, there’s a better way to address it than eliminating bananas from your smoothies.
But what if you were eagerly anticipating the antioxidants in your fruit smoothie? After all, flavon-3-ols like (-)-epicatechin are so beneficial that the Academy of Nutrition and Dietetics (AND) has even issued a guideline for them, despite the fact that flavon-3-ols are a non-essential nutrient. This guideline recommends that we consume at least 400 milligrams of flavon-3-ols per day for their health benefits.
To boost your intake of flavon-3-ols, the best option is to drink tea. Just 10 ounces of green tea (about two small cups) or 12 ounces of black tea will get you to that 400-milligram goal. While flavon-3-ols are also present in berries, you'd need to consume significantly more—6 cups of blackberries or 40 cups of blueberries—to match the same flavon-3-ol content in just two cups of green tea.
It's also worth noting that the same AND paper recommending the 400-milligram daily intake of flavon-3-ols advises against obtaining this nutrient through supplements. This is because the most common sources, such as green tea extracts, can lead to stomach issues and may even cause liver toxicity when taken in large quantities.
