In a recent prospective cohort study published in the journal Scientific Reports, researchers investigated the association between flavonol intake and cause-specific and all-cause mortality risk in adults in the United States. They found that an elevated dietary intake of flavonol is associated with a lower risk of all-cause mortality as well as Alzheimer's disease (AD), cancer, and cardiovascular disease (CVD)-related mortality risk.
Study: Flavonol-rich diet linked to lower mortality and disease risk, study shows. Image Credit: sematadesign / Shutterstock
Background
Flavonoids are biologically active polyphenolic compounds found in various plant-based foods. Among the six subclasses of flavonoids, flavonols are the most prevalent and active. Primary flavonols like quercetin, kaempferol, myricetin, and isorhamnetin are abundant in tea, onions, and berries. The consumption of flavonoids is known to potentially enhance endothelial function, maintain nitric oxide status, and influence biological processes relevant to lipid metabolism, platelet function, inflammation, oxidative stress, and blood pressure. Additionally, flavonoids are also known to exhibit anti-tumor effects by targeting key molecules and pathways, leading to apoptosis and inhibiting cell growth and metastasis.
However, the relationship between flavonol intake and mortality risk has not been studied thoroughly so far. Therefore, using data from the National Health and Nutrition Examination Survey (NHANES) database, researchers in the present study explored the relationship between flavonol intake (total flavonol, kaempferol, myricetin, isorhamnetin, and quercetin), all-cause mortality risk, and cause-specific mortality risk (AD, CVD, cancer, and diabetes mellitus (DM)).
About the study
The study included 11,679 individuals aged≥ 20 who completed questionnaires, in-person assessments, and laboratory tests. The exclusion criteria were lack of flavonol intake and missing basic and demographic information. Flavonol intake data for the present study were derived from the US Department of Agriculture Survey Food and Beverage Flavonoid Values database (2003–2004). Detailed dietary interviews were conducted to capture information on foods and beverages consumed in the preceding 24 hours. The precise amounts of total flavonols were estimated in various foods, and the daily flavonol intake of participants was calculated.
For mortality analysis, data from the National Death Index file and the 2019 Public Access Link mortality dataset were used. Mortality was categorized by causes such as cancer, CVD, DM, AD, and other causes, as per the International Statistical Classification of Diseases and Related Health Problems 10 (ICD-10) codes. Follow-up was conducted from the interview date to either the date of death or the study's conclusion on December 31, 2019. Participants were stratified based on sociodemographic variables, including age, sex, race/ethnicity, marital status, education level, poverty ratio, alcohol consumption, body mass index (BMI), disease history, and the presence of various health conditions. Statistical analysis involved the use of Cox regression, Fine and Gray competing risks regression models, hazard ratios (HR), chi-square tests, and sensitivity analyses.
Results and discussion
Participants with the highest total flavonol intake tended to be male, younger, Non-Hispanic White, married, educated, above the poverty line, alcohol consumers, with BMI 18.5–30.0 kg/m2 and had a history of DM, hypertension, hyperlipidemia, congestive heart failure, coronary heart disease, angina, heart attack, and stroke. Increasing total flavonol intake showed a declining trend in all-cause mortality as well as AD, cancer, and CVD-specific mortality (p < 0.05 for all). Similar decreasing trends were observed for isorhamnetin, kaempferol, and quercetin intakes across various mortality categories, while myricetin intake exhibited a decreasing trend in AD mortality.
While higher age was associated with a significant increase in all-cause mortality, female gender was found to be significantly linked to a lower risk of all-cause mortality. Conversely, a history of diseases was significantly associated with a higher risk of all-cause mortality.
Further, higher total flavonol intake, particularly isorhamnetin, kaempferol, myricetin, and quercetin, was found to be associated with a reduced risk of all-cause and mortality owing to AD, CVD, cancer, and other causes. However, no correlation was found between flavonol intake and DM-specific mortality (p>0.05). The findings from the subgroup and sensitivity analyses aligned with the study's main findings.
Although the study is strengthened by its use of a multiple confounder-adjusted competing risks model to address competing risks of death, the study is limited by missing flavonol intake data, potential lack of generalizability, lack of data on primary food sources and dietary patterns, and the lack of exclusion of micronutrient supplement intake.
Conclusion
In conclusion, the present study establishes an association between dietary flavonol intake and overall mortality as well as cancer, AD, and CVD-specific mortality risk in US adults. The findings suggest that flavonol intake could be employed as an independent and reliable predictor of disease survival, offering patients the potential for health- and risk-management through dietary modifications.
Phase 1 study finds serine- and glycine-free diet boosts immune response in colorectal cancer