Tag Archive for: flavonoid

Flavonols: Eat, Drink, and Maybe Live Longer

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The analyses of the NHANES study on flavonols and mortality did more than just look at a class of phytonutrients; researchers also looked at the individual flavonols and how they impacted mortality. A little background first.

Flavonoids

Flavonoids are a group of phytonutrients made up of six classes of nutrients. They are flavan-3-ols, flavones, flavanones, anthocyanidins, and the previously mentioned flavonols. Each of those classes are made up of individual phytonutrients. Flavonols have four primary phytonutrients in its class: quercetin, kaempferol, myricetin, and isorhamnetin. We’ll skip the rest of the individual phytonutrients in the other classes because they weren’t part of the study.

The researchers examined the reduction in mortality for each flavonol phytonutrient. When comparing the first quartile (lowest) with the fourth quartile (highest) intake, not every phytonutrient reduced the mortality from all conditions. In other words, the overall reduction in mortality was greatest when looking at total flavonol intake, not in any single phytonutrient. Too often research focuses on single phytonutrients as potential treatments of conditions and diseases, so it’s great to see a study that looks at total intake of a class of nutrients.

Absorption

As mentioned, flavonols are one part of the flavonoids. One characteristic is that they seem to be poorly absorbed. Or are they? It could be that there are unknown genetic factors that impact absorption and/or utilization of those nutrients. It may be that when isolated from a plant, the absorption is interfered with in some way that’s not apparent. It may be that the microbiome has a role to play in absorption.

What is most likely is that when eaten or drunk in its natural or prepared state, it is the interaction of all the flavonols that help absorption. Or it may be the combinations of flavonoids found in specific foods that work together for absorption.

What foods have the highest flavonol content? When looking at mg/100 grams, raw onions, cooked onions, apples with the peel, brewed black decaf tea, and brewed black tea top the list. When looking at the top three consumed? Onions, black tea, and apples top the list, but beer comes in fourth place. While the amount per 100 grams is low, we consume a lot of it.

The Bottom Line

At the end of the day, the most important thing to know is that we have to consume flavonols to get the benefits. In reality, your mama was right: eat your fruits and vegetables. They’re good for you. And if you chase them down with a beer, that’s probably okay as well.

What are you prepared to do today?

        Dr. Chet

Reference: Nature Reports. 2024. https://doi.org/10.1038/s41598-024-55145-y2. Arch

How Flavonols Affect Mortality

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Observational studies are just what the title indicates: observing something over time. In the case of the National Health and Nutrition Examination Survey (NHANES), one of the objectives is to observe the relationship between diet and whether it impacts how long we live. I recently came across a paper that examined the relationship between flavonol intake and mortality. Observational studies cannot give cause and effect; they can only suggest a relationship, which would then be followed up with randomized controlled trials. That doesn’t happen often enough in nutrition studies; how do you blind subjects to the foods they’re eating? Therefore, we take what we can get.

Researchers wanted to find out the relationship between one class of flavonoids called flavonols and mortality. They used data from the volunteers in three different NHANES data collection periods who completed a 24-hour dietary recall with an in-person interview and telephone follow-up. This is about as good as it gets when collecting dietary data in such large studies—over 11,000 subjects.

After accounting for age, gender, and other factors, there was a clear relationship between flavonol intake and mortality. Total flavonol intake was associated with an overall decrease in all-cause, cancer-specific, and CVD-specific mortality risks. The decrease in hazard ratio was as much as cutting the risk in half (cancer-specific) and by one-third from CVD and all-cause mortality; results were not as clear for diabetes and Alzheimer’s disease. There’s more to this study, and I’ll cover it on Saturday including the foods with the highest flavonol levels.

What are you prepared to do today?

        Dr. Chet

Reference: Nature Reports. 2024. https://doi.org/10.1038/s41598-024-55145-y2. Arch

Flavanols: The Real Brain Food

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As I suggested in the last memo, the researchers did not prove their hypothesis that there would be an increase in measures of memory in all participants of the clinical trial. While disappointing, the secondary hypothesis might have been even more important because it was statistically significant.

They found that those with the lowest intake of flavanols from foods and drinks had the most improvement in measures of memory function. Makes sense: people who did not eat enough fruits and other foods containing flavanols saw benefits by supplementing with a specific amount of flavanols every day.

Researchers didn’t test to see if eating little to no foods containing flavanol resulted in a decline in memory function; that would fall into the category of “first do no harm.” Understanding that flavanols are beneficial for more than just memory, it would not be responsible to have a person decrease intake of them.

They also did not find additional benefits of taking the supplement for those with the highest intake of flavanols from their diet. That means that a great diet has great benefits.

There are three points we can take from this study:

  • Regular intake of flavanols from supplements can compensate for weaknesses in the diet.
  • Eating flavanol-containing foods provides a wide variety of flavonoids including anthocyanidins, flavan-3-ols, flavanones, flavones, and isoflavones. In my opinion, eating and drinking plant-based substances is a better approach; using additional flavonoids from supplements is a great insurance policy.
  • The memory tests used in the study focused on one area of the brain: the hippocampal area. Supplementation did not appear to impact the prefrontal cortex component of cognitive aging.

If we want to age with a vengeance, I think we should look at it as though every little bit helps. I also think that the earlier we begin developing the habit of eating more fruits and vegetables, plus drinking teas, coffee, and cocoa drinks, the better our brains will be. And as a bonus, the rest of our body gets to enjoy the benefits as well.

What are you prepared to do today?

        Dr. Chet

Reference: PNAS May 2023. https://doi.org/10.1073/pnas.2216932120h

Phytonutrients: Diet or Supplements?

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The study that we looked at this week demonstrated that flavonoid intake is related to socioeconomic status. It also demonstrated that most of that difference comes from the consumption of tea. All well and good.

What stood out to me was the lack of phytonutrient intake. While there were some small differences in the other flavonoids besides flavan-3-ols, the total intake of flavonoids was low. Even though we’re talking about just one class of phytonutrients, the total flavonoid intake minus the flavonoids from tea was about 140 milligrams per day. That’s reflective of a poor diet that does not include as many sources of phytonutrients as it should: not enough vegetables, fruit, beans, nuts, and others. And it hasn’t changed in the six years of the study. Most people still don’t eat enough plant-based foods to do themselves any good.

Supplements: An Insurance Plan

The study demonstrated the need for the regular use of supplements containing plant concentrates. A plant concentrate is the plant or its fruit or its root or its leaves, minus the water and the fiber. It should also have been harvested at the peak of nutrition, not the peak of flavor and taste. The plant concentrates contain all the phytonutrients that are contained within the plant, and that includes not only the flavonoids that were the subject of this study, but all of the other types of phytonutrients that we need on a regular basis.

The plant concentrates may be found in multivitamin-minerals, as part of a fruit-and-vegetable concentration, or maybe even as a stand-alone. We’re not talking about treating diseases with these supplements; we’re talking about getting the nutrition that you’re supposed to be getting from the foods that you eat (but you’re not). To me, this study pretty much proves that everyone needs to take supplements with plant concentrates every day. They provide good backup while you work on improving your diet.

The Bottom Line

If you want the best chance at preventing degenerative diseases, you need optimal nutrition. That starts with what you eat, including all those phytonutrient-containing vegetables, fruits, beans, grains, and aromatic herbs used to season your food. As a backup, take supplements that contain plant concentrates to complement your diet. It’s not either/or; it’s using them both to get to better health.

Paula and I will be taking some time off to work on more jobs around the house. We’ll be back after a short break.

What are you prepared to do today?

        Dr. Chet

Reference: J Nutr 2020;150:2147–2155.

Flavonoid Intake Varies by Demographic

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Besides the flavonoid intake, another purpose of this study was to find out if there were any socioeconomic differences between high and low flavonoid intake. Before I get to that, here are some of the results of this study.

The age group with the highest flavonoid intake was adults 51–70 with 293 mg/day. As education increased, so did flavonoid intake from 201 mg/day for those not completing high school to 251 mg/day for those with some college. Finally, the flavonoid intake remained the same throughout all three cycles of the study.

Socioeconomic status was correlated with flavonoid intake as well; the higher the status, the higher the flavonoid intake. Race, income, and education were all included in the analysis. But not all flavonoids—just flavan-3-ols. By nature of the analysis, flavan-3-ol intake was directly attributed to tea consumption. (If you want to try to increase your tea consumption, try making Paula’s Sugar-Free Sweet Tea; find the directions in the Recipe section of my Health Info page.)

The researchers were satisfied they had found a link to phytonutrient intake, specifically flavonoids, and non-nutritive factors. To me, it meant something entirely different and I’ll cover that on Saturday.

What are you prepared to do today?

        Dr. Chet

Reference: J Nutr 2020;150:2147–2155.

Getting Acquainted with Flavonoids

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Every vegetable, fruit, and spice we consume in the foods we eat and many substances that we drink contain phytonutrients. Just to make the subject even more complicated, there are different categories of phytonutrients including flavonoids, which are the most prevalent in our diet. Flavonoid intake is linked to reduction of diseases such as cardiovascular disease and cancer.

Here’s an example: turmeric is a spice and one of many plants that contain beneficial phytonutrients. Many of us use a turmeric supplement because it may help reduce pain and inflammation. Turmeric contains three major phytonutrients known as curcuminoids; curcumin is the most familiar.

Researchers wanted to check the flavonoid intake from subjects over nine years old who had completed two 24-hour recalls in two of three NHANES study cycles during 2011–16. Of all the dietary intake techniques in use, the 24-hour recall is the second most accurate available (food diaries are first). They used the dietary data to estimate the flavonoid intake of all subjects. The food or drink consumed with the most flavonoids: tea, although they found that nine year olds don’t drink much of it. But that’s not all they discovered, and I’ll cover that in Thursday’s Memo.

What are you prepared to do today?

        Dr. Chet

References:
1. J Nutr 2020;150:2147–2155.
2. https://www.ars.usda.gov/ARSUserFiles/80400525/Data/Flav/Flav_R03-1.pdf

Avocados: Nutrition Powerhouse

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Let’s finish up our look at avocados. I covered most of the micronutrients on Thursday but there’s one more group to go: the phytonutrients.

The avocado contains three classes of phytonutrients. The first ones are called phytosterols, plant-derived compounds similar in structure and function to cholesterol. Research shows that phytosterols may help prevent the absorption of animal cholesterol, and that can benefit our overall heart health.

Avocados are also high in carotenoid antioxidants such as lutein and beta-carotene. We tend to think about carotenoids in bright orange or red vegetables such as carrots or tomatoes. Those . . .

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