Tag Archive for: polyphenol

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

Food or Supplements? Yes!

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The results of the polyphenol study examining the impact on cardiovascular (CVD) risk factors were mixed. Here’s what the researchers found:

  • Neither the polyphenol-rich foods (berries, spices, herbs, teas, nuts, seeds, etc.) nor extracts had a significant effect on LDL- or HDL-cholesterol, fasting blood glucose, IL-6, and C-reactive protein.
  • When looking at the studies using polyphenol-rich food, there was a significant decrease in systolic and diastolic BP.
  • The polyphenol extracts had a significant effect on total cholesterol and triglycerides and had a greater reduction of waist circumference.
  • However, when both whole-food polyphenols and polyphenol extracts were used together, there was a significant reduction in systolic BP, diastolic BP, endothelial function, triglycerides, and total cholesterol.

The Upside

Polyphenols in foods and supplements were effective in reducing risk factors for CVD, both independently and when combined. This wasn’t a seminal paper that changes approaches to nutrition forever, but there were benefits. I think that’s something that was needed. It supports what my approach has always been: eat as healthy a diet as you can, and fill in the nutritional gaps with supplements.

The Problems

There were several issues. The studies included in the meta-analysis had little cohesiveness as to subjects used, sources of the foods, or the type of supplements; some used capsules while others used juices or drinks.

The issue with foods, among many, is the digestion and absorption of the active polyphenols. There’s competition with other nutrients and then the issue of the microbiome—is it functioning properly in every subject?

The issue with supplements, besides the delivery system, is whether the dose is appropriate or therapeutic. Would the amount of quercetin found in apples be the correct dose, or would you need to eat 10 apples? Would it respond the same way in the body isolated from the other polyphenols, or would another factor come into play?

The Bottom Line

In spite of its flaws, I think this study was fantastic. It demonstrated that nutrients extracted from foods can be effective in reducing CVD risk. It demonstrated that foods alone aren’t the answer and neither are supplements; it’s their use in a complementary fashion where the benefits may be found. The researchers set the stage for putting more effort into nutrition research, because there’s so much we don’t know. Yet. Until then, your best bet to support your health is to eat your vegetables and fruit, add herbs and spices, munch on seeds and nuts—and then supplement your diet with quality supplements.

What are you prepared to do today?

        Dr. Chet

Reference: https://www.sciencedirect.com/science/article/pii/S2161831323000029

Food or Supplements?

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One of the changes I’ve made in selecting topics to write about in these Memos is to read the table of contents of the scientific journals to which I subscribe, especially the nutrition journals. It’s easier to see what’s controversial by looking at news feeds, but they miss a lot of positive nutrition science. One question that’s ever-present is this: when it comes to nutrients, is getting nutrients from supplements as good as getting nutrients from food?

Researchers searched four databases of scientific journals to find randomized-controlled trials that examined the effect of either polyphenol-rich foods or polyphenol extracts on risk factors for cardiovascular disease (CVD). It’s estimated that there are more than 8,000 types of polyphenols, including flavonoids, polyphenolic amides, phenolic acids, resveratrol, and ellagic acid. You’ll find polyphenols in fruits, vegetables, spices, herbs, teas, nuts, and seeds.

They found over 1,100 studies that fit the profile. Using subject, statistical, and nutrient criteria, they whittled the number of studies down to 46. Then they conducted a meta-analysis of the impact of food and supplements on the following CVD risk-factors: systolic BP, diastolic BP, endothelial function, fasting blood glucose, total-, LDL-, and HDL-cholesterol, C-reactive protein, Il-6, and waist circumference.

Nutrition studies are usually messy, and this one was no exception. I spot-checked the 46 studies and found different foods for the polyphenol sources and different extracts for the supplements. Still, it was as well-done as such a study could be. I’ll give you the results on Saturday.

Tomorrow night is the Insider Conference call for March. The topic is the absorption of omega-3s, and I’ll also answer your questions. Become an Insider by 8 p.m., and you can participate in this live event.

What are you prepared to do today?

        Dr. Chet

Reference: https://www.sciencedirect.com/science/article/pii/S2161831323000029