Transcript
Adding banana to smoothies destroys their nutritional value. Said some annoying guy in the internet last week. That guy was me. And boy did it kick a hornet's nest. Getting over 10 million views, a whole host of angry comments, and a bunch of reaction videos. Some of those from accounts that I have tremendous respect for. Like Dr. Ids, that I pronounce it, Liam and Dr. Sarah Ballanty, who I just discovered through Liam's video. So thanks. If you're not already following all of them, you should be. Go do that. But I love a good debate. And school. I was always pretty good at it, because I do my homework, even for very where I chose not to cite the 27 research studies I read in preparation of making a broad statement. So, firstly, yes, saying destroys their nutritional value was intentional hyperbole designed to capture attention and give me an opportunity to talk about the cool science. Guess it worked. But I will take the deserved slap on the wrist for it. You were supposed to watch the whole video, realize we're only talking about polyphenols, and understand that if you blend a banana with some berries, it won't magically disappear all the vitamins, minerals, and fiber that they contain. PPO doesn't target all polyphenols equally, although it does have a pretty wide spectrum of effect. I'm working on a 15-minute-long YouTube video and article covering all the different critiques in detail. Coming soon. But here are some quick takeaways for anyone who doesn't want to do a super deep dive into the science. Blending banana with polyphenol-rich substances like berries, herbs and various powders, like cocoa powder that I put in my smoothies, has a net lowering effect on the potential health benefits that you can get from the polyphenols contained therein. In the same way that completely browned apple slices are not as healthy completely fresh ones. It doesn't make them unhealthy. The fiber, vitamins, minerals, and some classes of polyphenols remain unaffected. But if you're like me and concerned with optimizing your health beyond the level of just keeping a pretty healthy baseline, then this whole banana polyphenol thing is information to keep in mind. Not as an absolute rule, if you love the taste of strawberry banana, then go for it. Mental health and enjoyment are also super important. Nutrition is about balance. I love ice cream and I eat it pretty often. But I also try to build a life based behaviors and decisions that in aggregate raise the overall health baseline that I'm working with. So yeah, I no longer add bananas to my smoothies. Quick note, if you are adding bananas, then the less time you blend it and the faster you drink it after blending, the better. Now, here's a quick teaser of supporting evidence. PPO is well understood. It's been studied for decades, because it's what causes the majority of fruit browning, which is commonly accepted in scientific literature to lower both the perceptual taste properties and the nutritional value of produce. to up to 50% of produce being thrown out before it ever hits a consumer. One quick example of PPO's broad spectrum action is this study, which showed it to break down one of the main categories of polyphenols found in berries, called anthocyanins. Not directly, as Dr. Sarah points out, but through secondary oxidative processes. Now for my favorite example. So we don't actually know what effects PPO has on the other types of polyphenols, and berries contain lots of different types of polyphenols, including procyanodins. Apples contain lots of healthy polyphenols, especially prosyanidins, natural PPO, but they're all bound up within different parts of the cell to keep them from interacting with each other. Slicing through an apple damages those cells, releasing the PPO, exposing it to oxygen, and causing it to then react and oxidize a lot of those polyphenols, degrading them into the brown pigments that you see. That's what a blender does, but way more. This study took apples and compared blending them with juicing them, which doesn't break apart the cells as much, and for their control, they did the same thing, but with mostly inactivated PPO in the apples, which they did through a blanching process. You can see the The results. Blending with the PPO active led to serious browning, and the effect is not just aesthetic and sensory. They measured the total polyphenolic content, the total flavonoids, a subset of polyphenols, and the functional antioxidant capacity of the resulting mixtures. This is blended with the PPO versus the PPO mostly inactivated. 60% of the total polyphenols were destroyed during the blending process. 66% of flavonoids were destroyed during the blending process. Antioxidant activity down by roughly half. Conclusion? breaks apart the cells, mixes the contents with heat and oxygen, and thus creates the perfect environment for PPO to degrade some of those healthy compounds found in apples, lowering their practical nutritional value. Bananas contain six times the amount of PPO as apples do. But most other fruits contain way less, so it's not such a big concern unless you add it back in. And again, there's plenty of other evidence to show PPO working on a pretty wide spectrum of polyphenols that they all contain. And here's a key point. That original study had an N of 6, but mechanistic studies can get a lot of the other. of statistical power, even from small sample sizes, when there's a large effect size. I don't need to mix bleach and ammonia a thousand times to tell you that it's going to produce a poisonous gas that you should not breathe in. The Nobel Prize was awarded for showing that HP Lorry bacteria can lead to ulcers after Dr. Barry Mulcher, ugh. After Dr. Barry Marshall drank them himself, got symptoms, and then got rid of the symptoms by taking an antibiotic, an n-equals-1 experiment, which then got replicated more. And yes, I would love to see a bunch of studies measuring the exact polyphenolic content when you blend banana with every possible combination of berries and herbs under the sun. But for now, these studies give me enough confidence to remove banana from most of my daily smoothies, especially when I'll be sipping them over the course of hours and saving the rest for the next day. You can easily see the color change when you do that. The full video and article are coming soon with dozens of citations for you real nerds, so follow on YouTube and subscribe to my newsletter to make sure you get it. Oh, and if you are one of my debunkers, reach out. I'd love to share the article with you in advance of publication and get your feedback so we can make this a cool dialogue.
Additional notes
Some points: 👉 I will still be making peanut butter banana protein smoothies as a nice and easy way to get my protein and creatine around gym-time. 👉 Dr. Sarah brings up a great point that SOME PPO reaction byproducts are actually BENEFICIAL compounds, especially in the case of green tea turning to black tea. But even there, the NET nutritional value went down–and that’s one of a smaller subset of cases 👉 PPO does come in multiple forms which have some minor differences in activity and preferred substrates. PPO is actually what produces freckles in our skin! 👉 Yes, it’s always a theoretical possibility that those 6 white men all have some weird genetics or local microbes that skewed the data. But the odds are quite low, and it’s pretty clear that a lot of the effect happens even before ingestion. 👉 It’s times like these when I sometimes get annoyed at the poor quality of many research studies. I went down a rabbit hole trying to trace the source of most of the claims around browning destroying nutritive value, and I ended up finding some good sources (including the apple study I talk about), but a whole bunch of other papers just daisy chain citations and sometimes tweak the language. I bet some authors never even looked into it much. 👉 Here’s one of the older but thorough review studies of the topic: doi: 10.1021/jf950394r 👉 GO follow @theplantslant , @drsarahballantyne , @dr_idz I’m sure we’ll still end up disagreeing on some aspects of this, but hopefully this video (and the followup) helped to clarify some of the issues! For the 7 of you that will watch the whole thing 🤦♂️ #health #nurition #science #lifehacks #smoothies