close-up of person's hands as they prepare kaleShare on Pinterest
Diets rich in foods that contain a high amount of naturally occurring compounds called ‘flavonols’ are associated with a lower risk of death and disease. Image credit: Sergey Narevskih/Stocksy.
  • Flavonols are natural compounds present in plant-based foods like fruits, vegetables, and tea leaves.
  • A new study shows that consuming a flavonol-rich diet is associated with a lower risk of all-cause mortality and mortality risk from certain chronic diseases.
  • Experts recommend increasing flavonol intake through a healthy and varied diet rather than relying on supplements.

Flavonols are a type of flavonoid, potent bioactive compounds found in almost all plant-based foods.

Previous research suggests a flavonoid-rich diet may help keep blood vessels healthy, balance cholesterol levels, reduce inflammation, and lower the risk of heart issues.

They may also play a role in preventing cancer by eliminating carcinogens from the body and stopping cancer cells from growing and spreading.

Now, a prospective cohort study has further emphasized the potential benefits of a flavonol-rich diet in reducing mortality risk.

The new study investigated the association between the intake of dietary flavonols — isorhamnetin, kaempferol, myricetin, and quercetin — and the risk of all-cause and disease-specific mortality in adults in the United States.

The findings are published in Nature.

In this study, researchers analyzed dietary flavonol intake data from three cycles of the National Health and Nutrition Examination Survey (NHANES) database, spanning 2007 to 2019.

NHANES participants were eligible to provide information regarding their food and beverage intake for two non-consecutive 24-hour periods. The present study excluded participants without dietary flavonol intake data or with incomplete demographic information.

A total of 11,679 participants, with an average age of 47, were evaluated for their flavonol intake and examined for disease-specific and all-cause mortality risk.

The researchers obtained data on dietary flavonol intake from the USDA Survey Food and Beverage Flavonoid Values, while they determined specific amounts of flavonols in each food item using the USDA Nutrient Data Laboratory. They used this comprehensive information then to calculate the estimated daily flavonol intake of participants.

To analyze mortality risk, researchers utilized the National Death Index file and the 2019 Public Access Link mortality dataset, categorizing mortality according to specific causes, including cancer, cardiovascular diseases, diabetes, and Alzheimer’s disease.

The study followed participants from initial interview until death or end of study in December 2019, with a median follow-up of 7.8 years.

Participants were divided into subgroups according to various sociodemographic factors — including age, sex, and poverty ratio — and disease history to assess the impact of flavonol intake.

The researchers used a multi-confounder-adjusted competing risks model to account for competing mortality risks.

The study found that the sociodemographic groups with the highest total flavonol intakes were:

  • males (55.84%)
  • younger (with only 2.15% being 80 years or older)
  • non-Hispanic white (74.6%)
  • married or living with a partner (67.95%)
  • individuals with at least a high school diploma (86.84%)
  • those living above the poverty line (89.63%)
  • alcohol consumers (92.80%)
  • individuals with a body mass index (BMI) between 18.5 to 30.0 (63.50%).

A significant portion had a history of diabetes (72.50%), hypertension (57.52%), hyperlipidemia (26.58%), and heart-related conditions (95.60%–97.53%).

Notably, every 10-year increase in age was associated with a significant increase in mortality risk. A BMI below 18.5 or a history of diseases were also significantly associated with a higher risk of all-cause mortality.

The data suggests that despite the highest intake of flavonol being predominantly among male and non-Hispanic white participants, being female or Mexican American was significantly related to a lower risk of mortality from all causes.

After adjusting for health and sociodemographic factors, the analysis revealed significant associations between total and specific flavonol intake and mortality risks from various causes.

The highest intake of dietary flavonols reduced the risk of cancer-related mortality by 55%, cardiovascular disease mortality by 33%, and risk of death from other causes by 36%.

Comprehensive findings also highlighted specific flavonols, each contributing to substantial reductions in all-cause and disease-specific mortality risks.

Of note, the highest myricetin consumption exhibited a staggering 66% decrease in Alzheimer’s disease-specific mortality risk.

The researchers observed no significant correlation between dietary flavonol intake and mortality risk from diabetes.

The study results also revealed that the consumption of flavonols had a greater protective effect against all-cause mortality in those over 40 years old than in younger individuals.

These findings suggest diets rich in flavonols could significantly lower the risks of death from cancer, heart disease, Alzheimer’s disease, and other causes among U.S. adults, particularly in mature or aging populations.

The study’s findings on flavonol intake and mortality are limited by a partial dataset from the NHANES database and an estimation of flavonol intake that might not accurately reflect consumption over the study period.

Further research is needed to confirm the results, considering additional dietary factors such as total calorie intake and micronutrient supplement usage, which could influence the observed flavonol effects.

Medical News Today discussed this study with Dr. Thomas M. Holland, a physician-scientist at the RUSH Insitute for Healthy Aging, Rush University System for Health, not involved in the study.

He said: “[I]t is a little challenging to establish the dietary intake of flavonoids from 24-hour recalls instead of food frequency questionnaires that would provide a bit more robust data on typical food intake habits or behavior.”

However, he suggested that 24-hour recalls provide adequate data and that the study design and sample size were strengths.

The health benefits of flavonoids are well established, but this study is the first to thoroughly explore the relationship between dietary flavonol intake and cause-specific mortality in humans.

So, while it has its limitations, Dr. Holland explained, “[t]his study really moves the research that has been done over the last 15 years — particularly in the last 4 years —forward in a great way.”

“One notable aspect of the study is its detailed analysis of various types of flavonols, including total flavonol, isorhamnetin, kaempferol, myricetin, and quercetin,” added Michelle Routhenstein, RD, a registered dietitian who specializes in preventative cardiology nutrition at Entirely Nourished, and who was not involved in this study.

“By considering these specific flavonoid compounds, the study provides a nuanced understanding of how different components of flavonoid-rich diets may influence mortality risks,” she said.

Dr. Holland emphasized:

“The primary aspect here is that the data shows a reiteration that consumption of nutrient and [bioactive] rich foods in a healthier diet is associated with decreased risk of some of the most detrimental non-[communicable] disease processes that plague the world.”

To incorporate more health-promoting, flavonol-rich foods, Dr. Holland suggested an overall shift to a healthier diet, such as the MIND diet or the Green Mediterranean diet.

“These diets stand as one of the preeminent ways we can safeguard cognitive health while also mitigating risks for Alzheimer’s dementia, all-cause mortality, cancer, and cardiovascular disease, given their robust flavonoid concentrations,” he explained.

Kiran Campbell, RDN, registered dietitian and owner of Kiran Campbell Nutrition, not involved in the study, agreed that a broader focus on diet is essential.

Studies suggest that the overall intake of fruits and vegetables provides more health benefits than focusing on a single plant compound like flavonoids,” she said.

According to Routhenstein and Campbell, for those looking to incorporate more flavonols into a healthy diet, some of the richest sources include:

  • tea: green and black tea
  • chocolate: dark chocolate or cocoa
  • legumes: chickpeas and soybeans
  • fruit: apples, grapes, cherries, citrus fruits
  • vegetables: red onion, artichokes, bell peppers
  • berries: black currants, cranberries, and other berries
  • herbs: dill, parsley, and oregano
  • dark leafy greens: spinach and kale
  • grains/pseudo-grains: buckwheat and quinoa

Are food sources of flavonols better than supplements?

In short, yes. Obtaining flavonols from whole foods is preferable to supplements.

While flavonoid levels are not concerning in the amounts found in foods, high-potency supplements can lead to excessive consumption and flavonoid toxicity.

Flavonoids are often considered safe because they are natural, but supplements may exceed safe intake levels or interact with medications, leading to potential risks, warned Campbell.

Dr. Holland further suggested:

“[C]onsider incorporating whole fruits and vegetables into your diet and enjoying a cup of tea. If you decide to use supplements, it’s recommended to do so under the guidance of your primary care physician to help address any nutritional gaps you may have. This approach allows you to benefit from the diversity of quantity and quality of nutrients found in whole foods, including valuable bioactives like flavonols.”

The study concludes that there is a significant link between the intake of dietary flavonols and mortality rates in U.S. adults.

The findings suggest that flavonol intake can help predict disease survival and that dietary modifications can be used to manage health risks.

In particular, flavonol intake may positively impact overall mortality rates and mortality rates specific to cancer, Alzheimer’s disease, and cardiovascular disease, reflecting flavonol’s potent anti-tumor, anti-inflammatory, and antioxidant effects.

Campbell explained that most chronic conditions begin to present during our later years, so individuals who have these conditions or are at a higher risk of developing them may find it encouraging to know that the protective factor against mortality was stronger for those over 40.

Dr. Holland agreed, concluding that although making changes earlier in life is ideal, “it’s never too early or too late to begin implementing healthy lifestyle adjustments, particularly concerning diet and physical activity.”