Bananas in Smoothies: Yes or No? (Presentation)

Last week I tried doing this presentation live on Friday, November 17, as some of you witnessed. Due to technical difficulties, that didn't work out as planned. Instead of trying to reschedule again, I decided to record the presentation so you could get the information as soon as possible!

You may have heard about a new study suggesting that an enzyme in bananas called polyphenol oxidase—the enzyme that turns bananas brown—can destroy a class of nutrients found in foods like berries. So, should you stop putting bananas in your smoothies? Is there anything we can add to the smoothie to counter the banana enzyme’s effects? Is it just a smoothie thing? What about eating a banana with meals?

And what about other fruits and vegetables that turn brown that also have this enzyme, like white potatoes, avocados, and white mushrooms? Is the enzyme destroyed by cooking? Get the answers to all these questions and more.

Here is the breakfast I mentioned:

My next live Q&A will be November 29 at 3 ET.

Sources cited:

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Dave McKinnon

  • says:

    Due to technical difficulties, Dr. Greger’s live presentation didn’t work out as planned last week. Instead of trying to reschedule again, he decided to record the presentation so you could get the information as soon as possible! Edited to add: here is a link to the sources cited in this presentation –

  • Galya Gerstman says:

    I’ve been using ripe bananas to sweeten my oats (with berries) instead of sugar but now I’ll try to replace them with mango or pineapple. Shame. Thanks so much for the info!!

  • My Mom says:

    Thank you Dr. Greger, I absolutely love learning these things from you😊
    Just when you think you are eating healthy, there is always another level!

  • Happily Vegan Since 2000 says:

    Thank you so much. I’ve seen a video by another YouTuber on this, or perhaps more than one, but this video is much better, explaining well as always and not stopping at pointing out the issue but going further to examine options for dealing with that antioxidant absorbtion blocking effect, and suggesting the best of these options. It’s indeed good to get this information as soon as possible. 👏🙏

    • Skippy says:

      I saw a video by Simon Plant Proof Podcast/YouTube about the banana study. Definitely Dr. Greger’s video explanation is much better. Not polished but who really cares when the details are sound.

  • Barbara Paessler says:

    So interesting ! Thanks for your ongoing work Dr. ! I so appreciate you ..

  • Michele Marks says:

    what if your smoothie is just greens, chiaseed, bananas and water? Are Bananas ruining the nutritional value of chia and greens or are they only adversely impacting the flavonols in berries and cacao if you choose to include them in your smoothies?

    • RiseUpBlue says:

      greens have antioxidants…I would think its the same effect. I swapped out bananas for mango or pineapple as a base.

  • ☨St Louis IX opposed paganism, hæresy & debauchery says:

    The Impact of Bananas on Flavanol Absorption in Smoothies and Other Nutritional Considerations
    🍌 The video discusses the importance of flavonoids, specifically flavanols, in cardiovascular protection and how polyphenol oxidase in bananas can affect their nutritional value.
    Flavanols, a type of flavonoid, can provide cardiovascular protection.
    A review suggests that an intake of 400-600 milligrams of flavonols per day would be beneficial for cardiovascular health.
    The primary sources of flavonols are tea, berries, and cocoa.
    Polyphenol oxidase in bananas can break down flavonols, reducing their nutritional value.
    Bruised bananas and cut avocados can produce defensive compounds with antimicrobial activity.
    Mixing banana with polyphenol-rich foods like berries or cocoa in a smoothie may result in less nutrition.
    Research showed that adding cocoa flavanols to a banana-containing smoothie led to a decrease in nutritional value compared to a berry smoothie with no banana.
    💡 Bananas in smoothies can decrease the amount of cocoa flavanols that make it into the bloodstream.
    The enzyme in bananas, polyphenol oxidase, can break down cocoa flavanols in the stomach.
    The levels of cocoa flavanols in the bloodstream decrease by 90% every 10 minutes.
    Adding polyphenol inhibitors can block the effects of the enzyme in bananas.
    The study participants had 37% less cocoa flavanols in their bloodstream when alternating sips of banana smoothie and chocolate milk.
    Bananas can decrease the levels of cocoa flavanols in the bloodstream by up to 37%.
    Polyphenol oxidase enzyme is deactivated in the stomach acid, but can still cause some damage.
    Drinking a smoothie immediately after blending can reduce the polyphenol damage caused by bananas.
    🍌 Bananas have high polyphenol oxidase activity, but white button mushrooms have even more.
    White button mushrooms have more polyphenol oxidase activity than bananas.
    Cooking mushrooms destroys the polyphenol oxidase activity.
    Mango has significantly less polyphenol oxidase activity compared to bananas.
    Apples turn brown due to polyphenol oxidase activity.
    Kale has very low enzyme levels, making it a good choice for green smoothies.
    🍌 Adding bananas to oatmeal or smoothies may decrease the absorption of certain nutrients, but heating or adding vitamin C and citric acid can help inhibit the enzyme responsible.
    Adding bananas to oatmeal or smoothies may decrease the absorption of certain nutrients.
    Heating bananas or adding vitamin C and citric acid can inhibit the enzyme responsible for nutrient absorption decrease.
    Pasteurized smoothie drinks may not have the same nutrient absorption issue as fresh-made smoothies.
    Adding lemon juice to fruit salad can prevent apples from turning brown.
    Sulfites were previously used to inhibit the enzyme, but they are now banned due to respiratory problems.
    Unsulfured dried fruits are recommended to avoid sulfite-induced respiratory problems.
    Alternative methods are needed to inhibit the enzyme in banana smoothies.
    🍌 Certain natural agents like onion extract and pineapple juice can prevent browning of fruits, including apples and bananas.
    Onion extract and fresh/cooked onion juice can prevent browning of pears.
    Pineapple juice seems to help keep apples and bananas from browning.
    Lemon juice is more effective than white wine in preventing browning in pastry dough.
    Bananas can be eaten anytime, but it’s better to consume them separately from other healthy foods.
    Having bananas in the stomach at the same time as a meal may impair nutrient absorption.
    Uncooked mushrooms and avocado can also have similar effects on nutrient absorption.
    The video provides important information on preventing browning of fruits and will be available on

  • Russ B says:

    Thanks Dr Greger! I had already made the switch to frozen mangoes in my smoothie to replace the bananas’ sweetness, so I guessed right! I’ll skip the onion juice though.

  • krawl b4 Walking says:

    Dr. Greger, this one truly bummed me out. 🍌 🍌 But thank you for keeping it real and for providing options of cooking and or adding citrus juices ie lemon / pineapple juice to yellow ( not brown) bananas to prevent / mitigate the negative impact.

  • Mel Stark says:

    Man, this is really frustrating for me. I never eat bananas until they start to be brown spots because green bananas are very starchy. I was under the impression that the more ripe a banana is the easier it is for your body to break down the sugars. I always have bananas in the morning with my smoothy or fruit bowl. So now, I shouldn’t?

    • Me says:

      I say do what you think works for you. This study is new I think and could change later. Just eat your breakfast fresh and don’t let the banana get too sweet (aka spotted). I love spotted bananas and will continue to do so 🙈! Best

    • Jeffrey Dotulong says:

      just put the damn banana’s in there. people put way too much faith in what science says. if you like bananas in your smoothies, put them in your smoothie.

    • Reasonable Vegan says:

      @Jeffrey Dotulongthis is a joke, right?

    • Jeffrey Dotulong says:

      it’s not. people are always scaring everyone off food. it’s really annoying.
      carbs are bad, this is bad, that is bad.
      how about stop making people scared of food, and let them find out what works for them.

      of course everyone knows already that junkfood isn’t good for you.
      but indulging in it every once in a while actually is.
      there is so much more to health as just science.

      it’s the emotional aspect of eating too,
      enjoying your food is a big part of health as well.
      i love bananas in my smoothies, and i am not going to stop because some supposed study says so.

      @Reasonable Vegan

    • Dana DeLaplante says:

      Said so right. Good comment. Just be mindful.💫💫✨✨🥑🥑@Jeffrey Dotulong

  • Kerstin says:

    Great info. Hope you follow up on this if you find out any better ways of disabling the polyphenol oxidase. Would like to see what this actually does to a real endpoint. Like if they split people into a mango+green tea smoothie or a banana+green tea smoothie group; would the mango+green tea group actually have lower blood pressure, less LDL etc?

  • Boas Janet says:

    Ok folks. No one is telling you what you have to eat. You can eat bananas in smoothies as much as you want.
    However, if you spend a lot of money on berries thinking you’re getting all the phytonutrient benefits, I think it’s helpful to know how to maximize those benefits. I don’t think anyone is saying bananas aren’t healthy. It’s just that you may be getting less than optimal benefits from berries
    I personally appreciate this video. Dr Greger himself said it’s not polished like his normal videos. He just wanted to get this preliminary rough video out there bc so many people had questions.

  • We Celebrate Eating Plants says:

    Thank you 🥦❤ So I’m wondering now what about that antimicrobial function of the browning going on there with the oxidation in the banana and the apple and does that help us thrive? Does it only antimicrobe against bad microbes? or is it universally hard on all microbial wellbeing? And is the brown in a ripe banana doing the same thing or is that a whole different world of brown? Are we supposed to stay away from all browned bits of banana or just keep them away from the berries and cocoa? Also cheers to Derek at Simnett Nutrition who has been suggesting for some time now to blend up banana in water and use that to cook oatmeal — cooked banana, being neutered, will not then have a deleterious effect on the berry goodness

  • Anju Madan says:

    Thanks for this video! Does microwaving the banana help?

  • Cathy Bojould says:

    Only Dr Gregor could make a 20 minute video on this topic lol

  • Ken Johnson says:

    I like fried bananas with cinnamon, nutmeg, cardamom and date syrup. This video gave me the idea of adding cacao and blending the whole mess into a smoothie. I’m going to go try it right now.

    • H C says:

      We will all be over to, ahem 🤤😋, help you evaluate it properly. I only need about 2 glasses full to um complete the testing procedures…😂

  • Summer Woodsong says:

    When we ran across this unfortunate info, we split our smoothies into morning berry smoothies and afternoon banana smoothies. We mainly use smoothies as a way to get our Daily Dozen berries and our apple cider vinegar. Splitting it into two separate recipes allowed us to have our berries without reducing their innate goodness and to still enjoy banana smoothies later. To increase bulk and smoothness in the berry smoothies we added in ground chia and some raw oats.

    • Krwiomocz.Bogurodzicy Ⓥ says:

      What kind of maniac puts ACV in their smoothies in any case? Sacrilegious… Why might you sprinkle it over salads instead?

    • Summer Woodsong says:

      @Krwiomocz.Bogurodzicy Ⓥ Neither of us like the taste of ACV – at all. Dr. G recommends a tablespoon of the stuff at a time. Putting it in our salads didn’t work, too dominant a flavor. But we discovered when we combine ACV with pineapple the vinegar taste takes a backseat and we don’t really notice it. So, all our fruit smoothies now include pineapple just to get the ACV down.

  • Kyle says:

    Would you be able to publish a smoothie matrix at some point to list the beneficial compounds of each common ingredient, and interactions that may eliminate them? Lol that would be appreciated for sure. It’s impossible to remember all of the data that comes out. It’s a mountain that never stops growing

  • richard pill says:

    At nearly 54 and over 7 years whole food plant based I am in the best shape of my life. I train most days ,have a six pack and eat a lot of bananas along with a wide variety of fruits and vegetables. I will still eat 4-5 bananas a day because they are GREAT! All the best. ❤

  • Chris K says:

    Great show. Thanks! Do you know whether a banana extract would contain PPO’s? I really like the flavor with my chocolate peanut butter smoothies!

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