 Hello everyone, hopefully third time is the charm. First time I got COVID when I tried to do this banana smoothies thing. And then just today, trying to do it as part of a live Q&A and technologically it all failed. So, although unfortunately this won't be live, won't be able to take questions, but I will get this information out there. And so hopefully this will work. Fingers crossed. Ah, right. Okay, well, so the first part of this is self-familiar who we're watching on YouTube or Facebook and don't all clash. But now you'll actually be able to see the PDFs. Hopefully actually see the studies that I'm talking about. Okay. We all know there are recommended daily intakes of essential nutrients like vitamins to prevent deficiencies, but recently, hopefully you can see that, but recently the first dietary recommendation for a bioactive food compound was published. Bioactive food compounds, as you can see in green here, are not necessary for basic human needs, but may have health benefits. For example, these plant metabolites here in red are known as flavonoids. Flavonoids are a type of polyphenol, which the most commonly consumed one is these flavon-3-ols, also known as just flavonols. A review of the literature here up in blue suggests that intake of 400 to 600 milligrams a day of these flavonols will be beneficial for cardiovascular protection such as, here in red, potential for improving blood pressure, cholesterol, blood sugars. Now note here in gray that this is specifically a food guideline, not a supplement guideline, though really it's actually more like a beverage guideline since, if you look at the zoom out a little bit there, if you look at the primary sources, it's really a tea, green or black is the easiest way to reach those levels, though there's certainly some in a variety of berries and cocoa. However, dun dun dun dun, there's an enzyme called polyphenol oxidase that can break down these wonderful polyphenols like flavonoids. That is what makes certain fruits of vegetables, as you can see here in green. Brown, when you cut them, such as bananas and potatoes, now why would a plant do that to itself? Well, apparently it is a defense mechanism. It's part of the plant's immune system, as you can see there in orange, and when exposed to oxygen, what happens is that polyphenol oxidase can oxidize polyphenols into these breakdown products which have antimicrobial activity. So, when a banana gets bruised, for example, there in gray, you cut up a avocado or something, the polyphenol oxidase can start oxidizing polyphenols into these defensive compounds that can glom together here in red, forming a dark compound called melanin. The same classic compound that darkens the skin of banana also darkens our skin, too. Okay, so no problem, we can just not eat bananas that have turned brown, right? Because that's visual evidence that many of the polyphenols have been lost. Ah, but what if you mix that banana, which you know is filled with that polyphenol oxidase enzyme, in a smoothie with polyphenol-rich foods like berries or cocoa, might that end up with less nutrition? Well, big chocolate-funded researchers sought to find out, and so, what they did is they put about a half cup of cocoa's worth of cocoa flavonols in a banana-containing smoothie compared to the same amount in a berry smoothie with no banana. So, here is a measure of how many cocoa flavonols make it into your bloodstream within hours, one, two, three, four, five, six hours after eating the chocolatey berry smoothie compared to the same amount of cocoa blended into a banana smoothie, right? So, the same amount of those cocoa goodies, but it's almost as if there was no cocoa in there at all, presumably because the banana enzymes chopped up all the chocolate goodies. Let's not presume, though. They blended up that chocolatey banana smoothie again, which was just banana, almond milk, cocoa flavonols, and then they just measured the level of flavonols as the smoothie sat for an hour. Check it out! That is what happened. The cocoa flavonols plummeted more than 90% a half-life of about 10 minutes. So, every 10 minutes, the levels of polyphenols drop in half. Now, how do we know it was for sure? It was this polyphenol-oxidase enzyme, because then if you add various polyphenol inhibitors, then they block the effect. So, no problem if you add bananas to your smoothies, just you have to chug them down before the enzyme does its job, right? I mean, presumably, the enzyme would be deactivated when it hit the acid bath of our stomach, but you don't know until you put it to the test. And I love that the researchers did all this, all these extra steps here. So, here you are in green here. What they did is this time, they had studied participants alternate sips between a straight banana almond milk smoothie and like chocolate milk, chocolate flavonoids plus the almond milk, right? So, there was no premixing in the blender between the banana enzyme and the flavonols, just mixing in the stomach. Such an elegant research move. Okay, so, here's how many cocoa flavonols. Here we go. Here's how many cocoa flavonols. Make it in your bloodstream sipping the chocolate milk alone here with these kind of brown, greenish-brown little data here. And then, here is when it's mixing just in the stomach when you're alternating sips with the banana smoothie. And so, that you get 37% less in your bloodstream, showing that the banana enzyme can still do some polyphenol damage in your stomach. It's starting to get dark. And so, my screen is going to start to yellow because I cut out the blue blocker, a blue bar artifact, but I just turned that off so we should be good. Okay. And indeed, in a simulated stomach acid, in kind of simulated stomach acid conditions, yes, the polyphenol oxidase is indeed down, but not out. Okay. So, yeah, if you drink some smoothie with a banana and it's better not to let it sit around, but even if you drink it immediately, you can get less polyphenols in your system than if you had to skip the banana. All right. But bananas make smoothies so rich and creamy. I mean, anything we can add to the smoothie to counter the banana enzymes' effects, that's exactly what I'll cover next. But not really next because that's what I would have said in a video, but we're all going to be covering right here, right now. Actually, let me turn down that light a little bit. Oh, it's not showing up. All right. That's okay. It's okay. All right. Let me just take a few seconds, though, before I continue with the story to ask for your help. We usually made this a YouTube fundraiser, but now it's not really on YouTube. But if you're watching this on nutritionfacts.org and you find this valuable, please consider making a tax-deductible donation to support this wonderful work. And so as a kind of end of year show of thanks, we don't accept money from food companies or supplement companies or kitchen gizmo companies or anything like that, just individual donors like you. So thank you so much for your support. Okay. Back to our regularly scheduled program. There's one food that has even more polyphenol oxidase activities than banana, and it's a vegetable that's not a potato. What vegetable turns brown? That's not a white potato. All right. Let's go look. Okay. 220. Let's find out. Aha. Here we go. So here's polyphenol oxidase activity in various fruits and vegetables and white mushrooms. White button mushrooms, as you can see, have more polyphenol oxidase activity than even bananas. Now, for those of you thinking, don't worry. I don't think I expect to be adding any mushrooms into my smoothies anytime soon. Now, some people do add avocados to smoothies or make like a chocolate avocado pudding. And here's a question. What if you eat mushrooms with a meal packed with polyphenol rich foods, right? Might it mix in your stomach and decrease the absorption like the anthocyanins in red cabbage or berries for dessert, right? And look, you could also be having some potatoes with your meal or eggplant with your meal, which also, as you can see, contains it. Now, note, though, however, this is for fresh produce, right? So, you know, we're not worrying about the eggplant potatoes. And the enzyme is utterly destroyed by cooking. So, this is inactivation of the mushroom polyphenol oxidase enzyme. And as you can see, it plummets readily. And look, remember, we should be cooking our mushrooms anyway, right? Because of the guarantee, most of our mushrooms, you don't have to cook oyster mushrooms, but the white and criminy portobello mushrooms, right? Problem solved, right? So, you don't have to worry about cooked potatoes, cooked eggplant, cooked mushrooms, okay. But who wants to cook their bananas, though, right? What else could we put in a smoothie instead? My personal favorite is mango, which you buy frozen when it's not in season. Do we have to worry about that? Having a polyphenol eating enzymes? Well, what happens when you cut open a mango? Does it go brown? No, it doesn't go brown, which should show you exactly what this data shows here. And that is, if you look, that mango, right here, has, oh, maybe 500 times less than that banana. This is polyphenol oxidase inactivity. This is the activity of that enzyme that destroys polyphenols like flavonoids, right? Now, the apple certainly doesn't surprise me, right? Because what happens with apples turns brown. But what is with these beet greens? I did not know about that. So, if you're making a green smoothie, better to use something like kale, which has enzyme levels so low, they're below the level of detection, okay? But, boy, this smoothie study raises so many interesting questions, right? So, forget smoothies. Should you not add bananas to your oatmeal, right? Because the bananas in your stomach would mix with like the berries or the cocoa that you put in your oatmeal. And indeed, that is what we should expect. So, I no longer add bananas to my Cran chocolate pomegranate breakfast bowl. That was one of my cooking videos, if you missed it. And since, you know, I don't want to lose any of those polyphenols. There's so many wonderful ingredients in that. I don't want to lose any. I don't want any of those destroyed, that 37% decrease in your stomach when it all mixes with that enzyme. Okay, but what if you're not making something chocolatey? The study only tested the effects of the enzyme on cocoa flavono. Like, they didn't check to see if mixing bananas with berries would affect the berry phytonutrients, but the presumption is that it would. And so, what does that mean for ready-to-drink bottled smoothie drinks that you might find in a store that may be sitting on the shelf? Well, if it's been pasteurized, then it should be okay, because the heat destroys that enzyme. That's why vegetables are blanched before they're frozen to destroy the enzyme. Even just heating bananas to 70... Let me see table two. That's figure two. I'm looking for... Oh, yeah, yeah, yeah, yeah. Okay, so here, this is inactivation methods for that enzyme bananas. Even just heating in here, we're looking at the T2 data right here. Even just heating bananas to like 70 degrees C, which is like hot tea, 70 degrees Celsius, for two minutes in the presence of vitamin C and citric acid, which might come from lemon juice, for example, would suppress the enzyme by 80%. I'm not suggesting drinking hot smoothies, but rather that those pasteurized smoothie drinks, depending on the ingredients, may not have the same problem as fresh-made smoothies. What about just adding the vitamin C and citric acid alone, like putting lemon juice in your smoothie? That is the T1... Oh, here, let me move this over. That's the T1 data here. And as you can see, it only cuts the enzyme activity by about 13% without the heating step. However, it does work wonders for apples. So, as you can see here, a cut apple, you just add some lemon juice, and you can cut that activity nearly in half, explaining why adding lemon juice to your fruit salad keeps the apples and your fruit salad from turning brown. Anything we can add to a banana smoothie to inhibit the enzyme, so we can still use bananas, but somehow block the enzyme? Well, they used to put sulfites in fresh fruits and vegetables to block that enzyme until they were banned in 1986. Following cases of sulfite-induced asthma, they are still used in dried fruit, though, to prevent browning. The apricots on the left are sulfured with sulfites, and the ones on the right are not. It's purely cosmetic. You want to get the un-sulfured, so you don't have to worry about sulfite-induced respiratory problems. Okay, sulfites are kind of off the table, but what about other... What about natural agents? What can we do for natural anti-browning agents to block this puppy? Well, as you can see in orange there, onion extracts can prevent the browning of pears, and you see in gray, both fresh and cooked onion juice both work, but there has got to be something better for your smoothies, and indeed pineapple juice, as you can see in purple there, does seem to help keep apples from browning, and bananas too, for that matter, but that was after soaking in pineapple juice for three days. It's not clear if it would work right away. There was a study here underlined in yellow comparing lemon juice and white wine to prevent browning in pastry dough. You've heard of hard cider, hard seltzer? Well, the lemon juice, it appears, beat out the wine, so better lemon squeeze than drinking a hard smoothie. Anyway, okay, so that's the... Let me stop sharing here. That's the story on bananas... Should you not eat bananas? No, you can eat bananas at any time. You just don't want to eat bananas. You just don't want to have the bananas in your stomach at the same time. You have other healthy foods like berries, cocoa, tea, and so, but like as a snack on its own, totally fine, but smoothies aside, still, you could impair some of the... You could destroy some of the phytonutrients if you had it in your stomach at the same time as meal and same thing with uncooked mushrooms and some of those other things, oh, like the avocado. Anyway, I'm sure this raises lots of questions, and I was hoping to take lots of questions today. That was before the tech disaster, but certainly be happy to answer next time I do Q&A. Thank you so much, everyone. Thank you for everyone who decided to support us this year. This topic will actually be up in actual video on nutritionfacts.org, all polished and fancy, but didn't want to wait for you to get this important information. Have a good night.