Tag Archive for: smoothies

Fruit: Variety is the Key

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I didn’t want to hold you in suspense, so I already revealed that you can put the banana in your smoothie if you like. I’ll tell you why, but first a little more about the study.

The biggest issue, which the researchers acknowledge, is the limited number of subjects. Eight subjects just aren’t enough, nor is 11 in the second study, to be able to make generalizations applicable to others. While it’s interesting, not every subject was impacted in the same way. The researchers didn’t use scatter plots so we could see exactly how the subjects were impacted individually.

The take-home message is don’t blend the fruit with the banana until you’re ready to drink it if you want to maximize polyphenol content, but there’s more to it than that.

Three Observations

Part of the reasoning the researchers had was that people may be selecting their foods based on the polyphenol or phytonutrient content. Have you ever selected the fruits you put in your smoothie, or even those you want to eat, based on the polyphenol levels? I haven’t. I eat fruit because it’s available, better tasting in season than not, and I want to reach that eight to ten servings per day. Polyphenols have never crossed my mind once in that decision.

While I’ve talked about the limited benefits of the study, there are three things we can take away from it.

  1. If you like a banana in your fruit-based smoothie, there’s no reason to change that approach. Even if this were a large study with enough subjects to increase the power and actually be meaningful, you’re not eating the same smoothie three or four times a day; either you’ll get tired of it or your body will adapt. To take a line from a movie, “Nature finds a way.”
  2. You should eat a variety of fruits and vegetables throughout the day. If you eat enough fruit from a variety of sources, you’ll get the polyphenols at some point. You don’t have to eat in some strange schedule to maximize phytonutrient content.
  3. If this study shows anything, it’s that taking phytonutrients in supplement form is an excellent way to complement a good diet. If you already use products with plant concentrates and phytonutrients in them, you may be ahead in the phytonutrient game. 

These studies were well thought out and well executed as pilot studies; let’s hope this is a prelude to a larger study from the same research group in the near future. One question I have is whether the consistent consumption of the same banana-blueberry smoothie consumed regularly over six months shows the same results or would there be some form of adaptation resulting in more polyphenol absorption? If I find out, you’ll hear it here first. What are you prepared to do today?

        Dr. Chet

Reference: Food Funct., 2023, 14, 8217–8228

Should You Skip the Banana?

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Over the years, I think I’ve made it clear that I don’t drink smoothies of any type. I’m also aware that it’s a preferred method for many people to get their fruit, protein, fiber, and other nutrients in a convenient manner. That’s why a recent press release for a study published in 2023 caught my attention; it claimed that bananas may impair the phytonutrient benefit of blueberries when blended in smoothies, specifically the polyphenols. Let’s look at the study.

The reason for the study was to test a specific enzyme known to reduce polyphenol content in fruit: polyphenol oxidase (PPO). Bananas contain a high amount of it; would it reduce the potential phytonutrient content of the berries? Researchers recruited subjects for two studies; eight volunteers for the first, 11 for the second. They tested whether a banana added to blueberries in almond milk impacted the phytonutrient content as well as the amount actually absorbed into the body. There were two controls: first, another smoothie made without banana, and a capsule with a specific flavanol content taken with almond milk. The second test did the same thing but did not blend the banana with the blueberry and milk.

The polyphenol capsule and the fruit without the banana came out about the same in polyphenol absorption.

The question is simple: does this really impact your morning smoothie with a banana? I’ll let you know on Saturday. Okay, I won’t make you wait—put the banana in the smoothie if you like it.

Tomorrow night is the Insider Conference call. You can still become an Insider or purchase a Guest Pass for $9.95 by 8 p.m. ET Wednesday, and a replay will be available within the following week if you can’t make it live. The topic is Sugar and Carbs—Fact or Fiction as well as answering your questions.

What are you prepared to do today?

        Dr. Chet

Reference: Food Funct., 2023, 14, 8217–8228

Should You Put Probiotics in Your Smoothie?

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Continuing with smoothies and shakes, another popular ingredient most people want to add are probiotics, either from yogurt or a supplement. Would there be any issue with adding probiotics to smoothies? No, as far as I could find. It’s the same idea as with the digestive enzymes: the probiotic will start to do its job, which is to ferment once it’s fed. Starches, prebiotics like inulin and dextrin, and fructooligosaccharides (FOS) are the preferential foods for the microbes.

Adding fruit or vegetables to the smoothie would be adding some FOS as well as some naturally occurring fibers. Again, just like the digestive enzymes, the shake would have to be left out a long time for any reasonable fermentation to occur. One more thing: while the probiotics would have fluids and food, the one thing they would not have in a smoothie is heat. Probiotics are not likely to start fermentation when they’re closer to refrigerator temperature than internal body temperature.

And one more thing. Would putting the probiotics in a blender at high speed damage the bacteria? The answer appears to be no based on comments from scientists who do research on bacteria. Imagine slicing a mosquito with a chainsaw; the blender’s blades aren’t small enough to slice and dice the bacteria, and the heat the blades generate isn’t enough to damage a significant amount of probiotics.

The one thing that will destroy probiotics is heat over 165 degrees, so don’t put them in soup or hot drinks. More to come.

What are you prepared to do today?

        Dr. Chet

What Do You Want to Know?

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I’m back from a weekend in Louisville where I talked to many, many people about their nutrition questions. One of the great advantages of these trips is that I know which nutrition questions are most important to people right now. So let’s talk about shakes.

I prefer chewing my food. I’ve tried shakes and smoothies, and they just don’t do it for me, but it’s become a convenient and nutritious way of life for many of you. I’ve gotten a number of questions on what you should and maybe shouldn’t put into smoothies, so let’s cover several of them as well as other questions in the next few memos.

Let’s begin with digestive enzymes. The typical digestive enzyme supplement has several different enzymes to digest food. There are proteases to digest protein, lipases to digest fats, several enzymes that can break down different classes of carbohydrates, and many also have lactases to digest lactase, the milk sugar.

What would putting digestive enzymes in smoothies do? Some enzymes require stomach acids to activate. More than likely, other enzymes would start to breakdown the nutrients they’re designed to digest. Is that a bad thing? Not necessarily, unless you leave the smoothie to sit for hours—which is exactly what you probably wanted to avoid. It may change the flavor if it sits too long but otherwise, it should be fine.

More on Saturday. And if you have any questions about nutrition or supplements, let me know and if I think it applies to lots of other people, your question could star in an upcoming Memo!

What are you prepared to do today?

        Dr. Chet