In September 2024, Dr. Michael Greger, a revered voice within the vegan neighborhood, raised an vital query a couple of breakfast staple for many people: ought to we embrace bananas in our berry smoothies? In his movies (Video 1, Video 2, Video 3), Dr. Greger highlighted analysis suggesting that bananas’ polyphenol oxidase (PPO) enzyme may degrade flavan-3-ols (compounds present in berries which might be nice for coronary heart and mind well being) so that you simply get much less goodness out of your costly berries. His conclusion? You must skip bananas in your berry smoothies. Use mango or pineapple as an alternative. Whereas Dr. Greger is a good man and his work at NutritionFacts.org has introduced us many nice analysis suggests through the years, there’s extra to this story. I did not just like the conclusion an excessive amount of myself since I, too, have been consuming each day banana and berry smoothies within the morning since about 1997. So, to comply with Dr. Greger’s recommendation would throw an actual kink in my each day meal routine, each for me and my household. We now have thrived on these smoothies.
This impact is one which you can see with your personal two eyes. You let a heat banana-strawberry shake sit on the counter. At first it’s all good and pink. Come again half-hour later, and also you marvel the place all the colour went. It’s strikingly pale, particularly with industrial strawberries. So, fairly some time again we developed some methods to make the colour last more, which signifies that we’ve restricted the PPO enzyme degradation fairly a bit.
Anyhow, I’ve dug into the analysis and located sensible methods to mitigate PPO’s results whereas conserving my favourite smoothies on the menu. Let’s take a more in-depth take a look at the science, discover out what the examine actually discovered about berries in smoothies, after which I am going to share some suggestions you need to use, too, to maximise flavan-3-ols in your eating regimen.
The Research: The place are the Flavan-3-ols Actually From?
The talk stems from a 2023 examine by Ottaviani and coworkers in Meals & Perform, which discovered that mixing bananas with flavan-3-ol-rich components in smoothies diminished flavan-3-ol bioavailability by a whopping 84%. The Determine 1 from the article is somewhat astounding and convincing (see beneath). Flavan-3-ols, like catechins and proanthocyanidins, are linked to diminished frailty and higher psychological well being as we age. However right here’s the important thing element: the berries within the smoothies did not present sufficient flavan-3-ols to measure properly, so the examine’s smoothies have been spiked with cocoa-derived flavan-3-ols (70–80 mg (-)-epicatechin), whereas berries contributed lower than 20 mg. The whole flavan-3-ol content material was excessive (484 mg for the berry smoothie, 638 mg for the banana smoothie, and 541 for the capsule management) excess of a typical berry smoothie (2–30 mg from 150 g berries, per USDA Database, 2018).
The 84% loss occurred as a result of bananas’ PPO enzyme oxidized flavan-3-ols throughout mixing, the place oxygen and tissue disruption activate PPO, after which continued working. A second experiment within the examine confirmed that consuming a banana drink and a flavan-3-ol-rich beverage individually (mixing solely within the abdomen) led to a a lot milder 37% loss (proven within the second determine, beneath). This means PPO is much less lively within the abdomen’s acidic, low-oxygen atmosphere (pH ~2–3) in comparison with contained in the blender or on the countertop. So, the examine’s massive takeaway isn’t nearly berries—it’s about avoiding mixing high-PPO fruits like bananas with flavan-3-ol-rich components, particularly cocoa or tea extracts.
Why I’m Conserving My Banana-Berry Smoothie
As a long-time smoothie drinker who loves my morning blended berry/banana/flax smoothie, I used to be initially involved by Dr. Greger’s movies. However the science exhibits that for a typical smoothie (150 g berries, 1 banana), the flavan-3-ol loss from berries alone is small—probably not more than 50% with correct mitigation, and nearer to 37% within the abdomen if I mix well. Berries additionally provide fiber, nutritional vitamins, minerals and different phytonutrients. These advantages, plus bananas’ potassium, magnesium, and fiber, make my smoothie price conserving. And mixing pulverizes the berries so properly, together with the blackberry seeds, so I do know I get as a lot as doable from my berries, far more than if I simply chewed them. So, right here’s how I mitigate PPO’s results to protect flavan-3-ols.
This is Easy methods to Mitigate PPO in Your Smoothie
You don’t must ditch bananas to take pleasure in berry smoothies. These science-backed approaches scale back PPO exercise earlier than the smoothie reaches your abdomen, limiting losses to the ~37% seen within the examine’s second experiment:
Hold It Chilly
PPO works quickest at 25–40°C however like all different enzymes it actually slows down once you get it right down to 4°C (39°F). We at all times use frozen berries, frozen pineapple, and ice in our morning smoothies. They’re chilly, and this retains the colour longer and quenches the PPO exercise of bananas fairly a bit.
Add Vitamin C
Ascorbic acid inhibits PPO by lowering oxidized flavan-3-ols and reducing pH. You possibly can embrace a tablespoon of lemon juice or 50 g strawberries for little bit of food-based vitamin C. We at all times put in about 1,000 mg of sodium ascorbate per particular person into our morning smoothies, as a result of it’s typically good for you, and it does assist with inhibiting the PPO enzyme. Sodium ascorbate works for this, too, not simply ascorbic acid, based mostly on private expertise.
Use Pineapple
Pineapple’s acidity (pH ~3.5), from malic and citric acid, additionally reduces PPO enzyme exercise. Add 100 g (~3 ounces) pineapple chunks for taste and safety. We virtually at all times put pineapple in our morning smoothies. The proteolytic enzymes in pineapple theoretically may assist break down the PPO enzyme in bananas, too, however I haven’t got any proof for this. Our smoothies are chilly, so the primary safety shall be in your abdomen, not in your glass.
Drink Instantly
PPO wants oxygen and time to degrade flavan-3-ols. Eat your smoothie proper after mixing to restrict pre-digestion losses. You’ll nonetheless lose some flavan-3-ols in your abdomen, however the losses beforehand shall be minimized.
These steps can scale back flavan-3-ol losses within the glass to close zero, leaving solely the ~37% stomach-based loss when bananas and berries combine throughout digestion. For a smoothie with 20 mg flavan-3-ols (e.g., 150 g berries), you’d retain ~12–16 mg (60–80% bioavailability) vs. ~3 mg with out mitigation.
However this subsequent step is absolutely what is going to get you the flavan-3-ols you’re in search of.
Enhance Flavan-3-ols with Inexperienced Tea
At the start of this text I identified that berries do not have loads of these flavan-3-ols to start out with. The actual champions are inexperienced tea and pure cacao, (present in minimally processed very excessive cacao merchandise). To make sure you get sufficient flavan-3-ols, you may add a cup of inexperienced tea later within the day, away out of your banana smoothie. Inexperienced tea is a flavan-3-ol powerhouse, delivering 240–430 mg per 240 mL cup (largely catechins like EGCG), with 50–260 mg absorbed . That is about 10X as a lot as you get from berries and simply covers any smoothie losses. Brew 2–3 g tea leaves at 80°C for two–3 minutes, and drink 1–2 hours earlier than or after bananas to keep away from mixing them collectively in your abdomen. (I am not a lot of a tea particular person, however I would take up consuming some inexperienced tea only for the well being advantages.)
When you don’t love inexperienced tea, however already take Hallelujah Eating regimen’s Joint Well being complement, then you’re set. You’re already getting a health-boosting quantity of procyanidins, that are flavan-3-ols as properly. Simply do not take your Joint Well being complement with something that has bananas in it.
Addressing Dr. Greger’s Considerations
Dr. Greger’s movies rightly spotlight PPO’s influence, however his name to keep away from bananas in berry smoothies is a bit excessive and untimely, as a result of it overlooks mitigation methods and the examine’s context. The 84% loss was pushed by cocoa-derived flavan-3-ols, not berries, and real-world smoothies have decrease flavan-3-ol content material (2–30 mg vs. 484–638 mg within the examine). With chilly temperatures, vitamin C, pineapple, and rapid consumption, losses drop considerably. Plus, separating flavan-3-ol-rich meals (like inexperienced tea, cacao merchandise, and grape seed extracts) from bananas ensures excessive consumption. These steps take the punch out of the “no bananas in smoothies” recommendation, letting us preserve our berry-banana smoothies and our inexperienced smoothies with bananas and berries in them whereas maximizing well being advantages.
Dr. Greger is true, in a single sense. To be a purist and to get the very most out of your berries, you’ll be able to take away the bananas. However, for me, that simply takes the enjoyment and delight and loads of diet proper out of my smoothie, for a really small acquire. Not price it for me. I might somewhat have a cup of inexperienced tea and get 10X as many flavan-3-ols, thanks very a lot.
Ultimate Ideas
Due to Dr. Greger for sparking this dialog, however the science offers us instruments to have our smoothies and flavan-3-ols too. By mitigating PPO with chilly temperatures, vitamin C, and pineapple, and including inexperienced tea later, we will preserve bananas in our berry smoothies with out fear. The examine’s findings are extra about cocoa than berries, and real-world losses are manageable. So, mix up your berry-banana smoothies, sip some inexperienced tea, and revel in one of the best of each worlds!
