Increasing your daily intake of flavonoid-rich foods may lower your risk of dementia

A large cohort study of UK adults found that consuming flavonoid-rich foods, such as tea, red wine and berries, was associated with a reduced risk of dementia, particularly in those with high genetic risk, hypertension or symptoms of depression.

In a recent study published in JAMA network openresearchers examined associations between flavonoid-rich food scores (flavodiet), flavonoid categories, and dementia risk. They also examined these associations in conditions of high genetic risk, hypertension, and depression.

Background

Dementia, a disease characterized by gradual deterioration of cognitive functions, impairs thinking, memory, and the ability to perform daily activities. The lack of effective treatments makes the disease an increasingly serious global health problem. Preventive therapies are key to improving health, reducing costs, and reducing the risk of dementia. Modifiable risk variables, such as food, play a key role in disease prevention, and plant-based diets have been associated with a reduced incidence of cognitive impairment.

Plant-based foods and beverages contain flavonoids, which have been linked to reduced risk of dementia, depression, and hypertension. Dietary flavonoids reduce neuroinflammation, increase cerebrovascular blood flow, and play a role in the gut-brain axis. These foods also affect neural pathways involved in synaptic plasticity. Identifying flavonoid-enriched foods associated with improved health outcomes could help develop dietary recommendations for intervention studies and population health efforts.

About the study

In this study, researchers determined the associations between flavonoid intake, flavonoid subcategories, and risk of dementia. They also examined these associations among genetically susceptible individuals with hypertension and depression.

The researchers analyzed dietary data provided by United Kingdom Biobank participants aged 40 to 70 years, recruited between 2006 and 2010 from National Health Service (NHS) registers. Participants completed the Oxford WebQ dietary questionnaire and underwent several biological and physical assessments. All participants provided at least two dietary records. Participants’ daily intake ranged from 800 to 4200 kcal for men and 600 to 3500 kcal for women.

The researchers created the flavodiet score by adding the intake of the main factors to the flavonoid subclasses and then estimated a cumulative average using the participants’ energy intake. The main factors were the three meals that contained the most of each flavonoid subclass. The exposures in the study included flavodiet score compliance and flavonoid subclass intake as measured by 24-hour dietary assessments.

The primary outcome was new-onset dementia and its association with hypertension, depression, and genetic risk. Individuals who carried the apolipoprotein E (APOE) ε4 genotype or were in the highest quintile of Alzheimer’s disease polygenic risk scores (PRS) were considered to be at high genetic risk for dementia. Data linked to mortality registries and hospital records confirmed dementia using International Classification of Diseases, Ninth Revision (ICD-9) and ICD-10 codes. Mortality data censorship dates were March 31, 2021 (Scotland and England) and February 28, 2018 (Wales). Researchers followed participants for nine years until the censorship date, dementia diagnosis, or death, whichever came first.

Multivariate Cox proportional hazards regressions determined adjusted hazard ratios (AHRs) 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, history of stroke, postmenopausal status, medications, comorbidities, and Healthy Plant-Based Diet Index (hPDI) scores. The researchers analyzed data between September 1 and September 30, 2023.

Results

Among the 121,986 people, the mean age was 56 years; 56% were women, 97% were white, and 882 had developed dementia. People in the highest quintile of Flavodiet scores were more physically active, had lower BMIs, and were less socioeconomically disadvantaged than those in the lowest quintile. When comparing the highest and lowest quintiles of Flavodiet scores, eating six extra servings of flavonoid-rich foods per day was associated with a lower risk of dementia among study participants (AHR, 0.7), those who were genetically susceptible (AHR, 0.6), and those experiencing depression (AHR, 0.5).

The researchers observed the greatest risk reduction in those consuming at least two of the three components daily: five servings of tea, 0.5 servings of berries, and one glass of red wine, compared with those consuming none (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 main components, confirmed the results, showing inverse associations with dementia incidence.

Sensitivity analyses of individuals aged ≥60 years followed for more than five years and those without a history of stroke yielded similar results. Analyses included genetically susceptible whites and less educated and physically inactive individuals living in regions with high levels of socioeconomic disadvantage. Removing hPDI scores did not change the results.

Application

The study found that increasing consumption of flavonoid-rich foods and beverages can reduce the incidence of dementia, especially in people who are genetically susceptible, depressed, or have high blood pressure. The results suggest that consuming six additional servings of flavonoid-enriched foods, such as berries, tea, and red wine, can significantly reduce the risk of new-onset dementia, especially in high-risk groups. Tea showed the highest association with reduced risk of dementia due to epicatechin, a flavonoid that inhibits the pathological effects of APOE.