Tag Archive for: National Health and Nutrition Examination Survey

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

Will Ultra-Processed Food Harm You?

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Use of ultra-processed food (UPF) has risen over the past 20 years; that’s clear from a recent study that examined eating trends. Using data from nine cycles of the NHANES (National Health and Nutrition Examination Survey) study, there has been a steady rise in the percentage intake of UPF from 53% to 57%. Over the same period, there has been a decline in minimally processed meat, chicken, and dairy products with an increase in UPF meats.

As you saw if you looked at the NOVA categories (first reference below), the largest component of the UPF are breads and sodas of all types, together with confectionary products such as cakes and pies. The first question: what has this rise in UPF done to our health?

UPF and Mortality

Researchers tracked adult participants in the 1988–1994 NHANES study. Over a median follow-up of 19 years, individuals in the highest 25% of servings of UPF per day had a 31% increase of mortality from all causes. Curiously, the increase in mortality was not from CVD—but dead is still dead, so it doesn’t really matter what caused it.

Recently published research associated UPF with type 2 diabetes, Alzheimer’s disease, and maybe most important, changes in the microbiome. That’s where the immune system begins, so the low fiber in UPF may actually be the root cause of the rise in mortality. Finally, as the servings of UPF went up, so did the caloric intake compared with the lower quartiles—an additional 600 calories per day.

One Nagging Question

I’ve talked about the sweet spot before: How many vegetables and fruits can we eat to offset some of the poor food choices we make? The data showed that minimally processed vegetable intake stayed constant at less than one serving per day and fruit and fruit juices declined over the nine NHANES survey periods. The researchers in both studies could have analyzed the data by intake of healthier food to see if that had any impact. Not that I believe we should increase our UPF intake, but for those who do, what can we do to offset some of negative impacts?

The Bottom Line

As 2023 continues, rather than tell you to reduce your UPF intake—which is a good idea—I’m going to propose that you add one vegetable or fruit serving to your daily diet every month, and do it early in the day. You might naturally reduce your UPF intake as a result. Because the recommendation never changes in our trio: eat less, EAT BETTER, and move more.

What are you prepared to do today?

        Dr. Chet

References:
1. https://educhange.com/wp-content/uploads/2018/09/NOVA-Classification-Reference-Sheet.pdf
2. Am J Clin Nutr 2022;115:211–221
3. Public Health Nutr. 2019. 22(10):1777–1785. doi:10.1017/S1368980018003890

Food vs. Supplements: A Closer Look

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There’s no question National Health and Nutrition Examination Survey (NHANES) has done the best job of collecting data on nutritional intake in large-scale studies. I’ve applauded it in the past, and I’m not going to change now just because there’s an NHANES-based paper that critiques the use of supplements. NHANES data were used by one of the co-authors of the current research paper we’re examining; in that study, they demonstrated regular use of a multivitamin-multimineral can compensate for deficiencies in our diet.

What could explain the same data showing potential benefits and hazards of supplements? Two reasons in my opinion. First, the research questions were not part of the original study; that’s supported by the fact that the lead author would have been six or seven years old when data collection began.

Imagine you apply for a loan. You’d give the bank all kinds of financial data: your total earnings, where you work, what you owe, and so on. Then imagine that researchers take all that very accurate data and estimate your hourly wage. They could be right on the money or way off, because they don’t know how many hours you worked; that wasn’t one of the questions. It’s the same with the data in this study; the researchers can make a great guess from the data they have, but the question they’re trying to answer wasn’t one of the original questions asked so their guess may be very far from correct. That happens often in these retrospective studies.

Second, the bulk of the researchers were experts in statistics and epidemiology. The statistical analysis accounted for 11 factors to numerically make the data comparable. We can’t really know what that does to modify the data instead of collecting data on actual variables.

Still worried? I’ll finish this up on Saturday.

What are you prepared to do today?

        Dr. Chet

Reference: Ann Intern Med. doi:10.7326/M18-2478.