Why Bananas Can Reduce Flavanol Availability in Smoothies

The first question, and there was sort of a related question from Stephanie and Steve about, first of all, my smoothie. So Stephanie says, on the call last month, you suggested we remind you to cover your smoothies. You said you had an update for everyone. Will you please address your smoothies? And then the related question from Steve was about bananas destroying polyphenols. And Steve asked if I had seen the study. And indeed, I did see the study and this was the reason for updating my smoothie ingredients. So let's just talk a little bit about that for those of you that are unaware of this recent study. So it came to my attention that there was, you know, basically adding a banana to your smoothie could, you know, negate and degrade polyphenols.

And those are obviously beneficial compounds. We've talked a lot about them. They're, if we're talking about in the context of a smoothie, usually they're found in the berries, like blueberries, for example, are high in polyphenols. So there's an enzyme inside that is in some foods and very high in bananas. And it's a— the enzyme is PPO, and it basically chews up and degrades polyphenols. So what this particular study did show was that if you drink, a smoothie that's high in, for example, epicatechin. So epicatechin is a type of polyphenol. It is found very concentrated in green tea. I've got my matcha, my Jade Matcha Green Tea here, and cocoa, but it's also in blueberries as well.

And so the PPO enzyme degrades epicatechin and therefore reduces the amount of epicatechin that's found in plasma in people. So, and we're talking, when I say reduces, I mean more than 80% reduction. We're talking just, you know, astronomical. So in a subsequent study, people were given, you know, polyphenols and they were co-ingested with a very high PPO banana drink. And in this context, the metabolites of the epicatechins or the polyphenols were reduced, basically suggesting that, you know, eating— and we're going to talk about what foods are high in PPO— eating foods that are high in PPO or blending them together, even eating them like a banana and blueberries or a banana mixed with blueberries, like I went and got, you know, an acai bowl the other day for my son and there was like banana and blueberries and acai and I'm like, oh, the banana, you know, is kind of negating all this, so we took the banana out.

What the study does not tell us is how high the PPO activity needs to be to have a significant effect on epicatechin or polyphenol levels. So we can only say that the activity of about 96 international units per milliliter, which is included in a drink that has about 50 grams of berries, so including blueberries and blackberries, raspberries, strawberries, these all have the polyphenols. That does not have a significant effect. So, so 96 international units doesn't do really anything to the polyphenols. But when you go really high to almost 9,000 international units, so this is a drink that now contains about 177 grams of banana, then you're having a really significant effect on lowering the polyphenol levels.

So it's difficult to— I would say it's difficult to extrapolate the results to other foods because they really only tested the PPO activity per mL of the drink and not per gram of the ingredients. I, you know, those polyphenols that were tested also were only the epicatechins, so there was not other types of polyphenols as well because there are, of course, a variety of different types of polyphenols. I would say it's in my opinion, and this is where I'm going to talk about a little bit where I've made a change in my smoothie ingredients. I think it's just best to avoid eating, mixing foods that are high, really the biggest food that's high in PPO is banana, but we'll talk about another one in a second.

So I would avoid mixing those foods together in the smoothie and just eating them right back to back if you're going to eat something with polyphenols, so that includes— You know, cocoa via. It includes you know matcha green tea. It includes you know all those types of blueberries, blackberries. You know all that stuff that has the polyphenols because it can degrade them, and I think that it's you know there's there's there's a good chance that it might affect your polyphenol levels, which is essentially what you don't want. So some foods that are high in PPO, I have a chart here. So banana is really the highest. So it's, you know, if you look at the activity of the PPO, it's about 3,258, you know, units per 100 grams. Now the other one that's really high are beet greens.

So these are the greens that are like come out of beets. And they're Those are close to 1,600 units per 100 grams. And I would say that what piqued my interest on the beet greens was I, oh, there's like, there's the stem and the leafy green and it kind of looks a little bit like chard. And so I started looking up Swiss chard because I often will add as a— Swiss chard is a great source of vitamin K1. It's a great source of lutein, zeaxanthin. Uh-huh. Of, you know, magnesium, calcium. There's a lot of micronutrients. It's a very, very healthy leafy green to eat. And so I would often add it to my smoothie if I had it around in the refrigerator. And apparently, the Swiss chard is much, much like the beet greens with respect to the PPO.

In fact, the first time that enzyme was ever isolated, it was isolated from Swiss chard. So that's the biggest change I've made to my smoothie is the Swiss chard. Apples, particularly Red Delicious, have about 570, you know, so significant drop from like a banana. But I would say, you know, after that, everything else kind of really drops down to almost nothing. So like, I was concerned about avocados because I add avocados to my smoothie, but avocados have a very, very low amount of PPO, like 24 units per 100 grams. So, just comparing the same units that we've been talking about. So I would say the bananas are the biggest thing. Swiss chard is also the big— another big one for me that I'm no longer putting in my smoothie.

Interesting tidbit of information, vitamin C is an inhibitor of PPO. So obviously, I mean, the berries themselves have vitamin C, you know, adding extra vitamin C in there could also help to maintain polyphenol content in smoothies. So that's another interesting piece of information as well. But nonetheless, I do think this is— I mean, it's extremely important, especially like a lot of kids' smoothies have bananas in them. So I think that, you know, it's kind of— it's good information. I'm certainly not putting bananas in my son's smoothie either. Some people in the chats were talking about Studies being poorly done. I don't know that it's necessarily poorly done. It was a small study, and there was a lot of things that weren't tested, like I mentioned, right?

I mean, but I think at the end of the day, the bottom line is that PPO is very high in bananas, and so a lot of people are adding bananas to their Blueberry smoothie, essentially. And the other take-home really is like if you're drinking your CocoaVia, so I typically drink my CocoaVia in the afternoon when I need a little more pick-me-up. I add a small amount to my coffee as well in the morning, but you know, make sure that you're not eating a banana and washing down the banana with some CocoaVia, right? Because then you're going to be degrading a good portion of those epicatechins that are doing so many beneficial things in the CocoaVia. So I think it's not just the smoothie, but just having the greater context, like having that information in your head.

Oh, if I'm going to have a banana, you know, like I shouldn't be eating it with my cocoa or my green tea or my blueberries or something with polyphenols. So I think those are the most important things. And then of course, I mentioned the chard. I still, yeah. You know, if I'm going to put chard in a smoothie, it's going to be a smoothie that is greens. It's going to be one of those chug it down for the, you know, for the greens, or the best thing— the other thing I like to do with chard is I like to, you know, just do a little bit of like blanching of it and eating them like a little bit, just a little bit blanched, and I think that's also a really good source. So, there's no other greens that I would be concerned about. There's no other greens that have any high PPO activity.

It's just really the beet greens and the Swiss chard. So spinach, kale, romaine lettuce, all of those things, all those types of greens are totally fine and they have a low PPO content. I think the biggest thing people have to worry about is spinach. A lot of people, I mean, think about any smoothie place you go to. Like the main staple ingredient in every smoothie is a banana. So I think that's the biggest take-home here is that bananas are really— most people are not putting Swiss chard in their smoothie. I mean, we do it, right? Like that's like we're trying to get a lot of the greens, but it's really the banana that I think has a broad application here. So that was the first question.

I thought that was a really good and important, you know, it wasn't like, comprehensive study, but I do think there's going to be follow-up studies on it. And I think that it's pretty simple to, you know, apply this to our life. It's not going to make that much of a difference. It's not like you can't eat bananas. It's just that I wouldn't eat them with— in combination with polyphenol-rich foods. And that's really the bottom line with that.