Increasing daily consumption of flavonoid-rich foods may lower dementia risk

In a recent study published in JAMA Network Open, researchers investigated associations between flavonoid-rich food (flavodiet) scores, flavonoid categories, and the risk of dementia. They also explored these associations in settings of high genetic risk, hypertension, and depression.

Background

Dementia, a disease characterized by gradual cognitive impairment, impairs thinking, memory, and the capacity to perform everyday tasks. The lack of effective treatments makes the disease a growing worldwide health concern. Preventive therapies are critical for improving health, lowering expenses, and decreasing dementia risk. Modifiable risk variables, such as food, play a crucial role in disease prevention, with plant-origin diets related to a reduced incidence of cognitive disorders.

Plant-based foods and drinks include flavonoids, which are related to decreased risks of dementia, depression, and hypertension. Dietary flavonoids decrease neuroinflammation, increase blood flow in cerebrovascular channels, and have a role in the gut-brain axis. These foods also affect neural pathways involved in synaptic plasticity. Identifying foods enriched with flavonoids related to better health outcomes can assist in developing dietary recommendations for intervention studies and population health efforts.

About the study

In the present study, researchers determined relationships between flavonoid consumption, flavonoid subcategories, and the risk of dementia. They also examined these relationships among genetically susceptible, hypertensive, and depressive individuals.

The researchers analyzed dietary data provided by United Kingdom Biobank participants aged between 40 and 70 years, recruited from 2006 to 2010 based on National Health Service (NHS) registers. Participants filled out the Oxford WebQ dietary questionnaire and completed several biological and physical evaluations. All participants provided a minimum of two diet records. Participants daily dietary intake ranged from 800 to 4,200 kcal for men and 600 to 3,500 kcal for women.

The researchers developed a flavodiet score by adding the intakes of the primary contributors to flavonoid subclasses, then estimated the cumulative mean using participant energy intakes. The primary contributors were the three meals that consumed the most of each flavonoid subclass. The study exposures were flavodiet score compliance and flavonoid subclass consumption as measured by 24-hour dietary evaluations.

The primary outcome was new-onset dementia and its relationship to hypertension, depression, and genetic risk. Individuals carrying the apolipoprotein E (APOE) ε4 genotype or those in the uppermost quintile of Alzheimer’s disease-associated polygenic risk scores (PRS) had a high genetic risk for dementia. Data linked to death registers and hospital records ascertained dementia using the International Classification of Diseases, ninth revision (ICD-9) and ICD-10 codes. Censoring dates for mortality data were 31 March 2021 (Scotland and England) and 28 February 2018 (Wales). Researchers followed the participants for nine years until the censoring date, dementia diagnosis, or death, whichever occurred first.

Multivariate Cox proportional hazard regressions determined the adjusted hazard ratios (AHR) for analysis. Study covariates included sex, education, socioeconomic status, ethnicity, race, smoking status, sleep duration, physical activity, body mass index (BMI), family history of dementia, stroke history, postmenopausal status, medications, comorbidities, and healthful plant-based diet index (hPDI) scores. Researchers analyzed data between 1 and 30 September 2023.

Results

Among 121,986 individuals, the mean age was 56 years; 56% were female, 97% were white, and 882 developed dementia. Individuals in the highest flavodiet score quintile were more physically active with lower BMI values and less socioeconomically deprived than those in the lowest quintile. Comparing the uppermost vs. lowermost quintile for flavodiet scores, consuming six additional servings daily of flavonoid-dense items was related to lower dementia risk among study participants (AHR, 0.7), genetically susceptible individuals (AHR, 0.6) and those experiencing depression (AHR, 0.5).

The researchers observed the highest reduction in risk among individuals consuming a minimum of two of the three daily: five helpings of tea, 0.5 portions of berries, and one glass of red wine, compared to those without such intake (AHR, 0.6). Increased consumption of flavonoid subcategories, including anthocyanins, flavones, flavan-3-ols, and flavonols, of which berries, tea, and red wine are the primary contributors, supported the results, with inverse relationships with dementia incidence.

Sensitivity analyses of individuals aged ≥60 years followed for over five years, and those without stroke history yielded similar results. The analyses included genetically vulnerable Whites and less educated and less physically active individuals residing in highly socioeconomically deprived regions. Removing hPDI scores did not alter the results.

Conclusion

The study found that increasing the consumption of flavonoid-dense foods and beverages may reduce the incidence of dementia, especially in those who are genetically vulnerable, suffer from depression, or have hypertension. The findings indicate that consuming six additional servings of flavonoid-enriched foods such as berries, tea, and red wine can significantly lower the risk of new-onset dementia, particularly in high-risk groups. Tea exhibited the highest connection with decreased dementia risk due to epicatechin, a flavonoid that inhibits APOE’s pathological effects.