A large cohort study of British adults shows that consuming flavonoid-rich foods such as tea, red wine and berries is associated with a reduced risk of dementia, especially among people with high genetic risk, high blood pressure or depressive symptoms.
From a recent study published in JAMA network openedresearchers examined associations between scores for flavonoid-rich foods (flavodiet), flavonoid categories and the risk of dementia. They also examined these associations in settings with high genetic risk, hypertension and depression.
Background
Dementia, a disease characterized by gradual cognitive impairment, impairs thinking, memory and the ability to perform everyday tasks. The lack of effective treatments makes the disease a growing global health problem. Preventive therapies are critical for improving health, reducing costs, and reducing the risk of dementia. Modifiable risk variables, such as food, play a crucial role in disease prevention, with plant-based diets linked to a reduced incidence of cognitive impairment.
Plant-based foods and drinks contain flavonoids, which are linked to a reduced risk of dementia, depression and high blood pressure. Dietary flavonoids reduce neuroinflammation, increase blood flow in cerebrovascular channels, and play a role in the gut-brain axis. These foods also affect the neural pathways involved in synaptic plasticity. Identifying foods fortified with flavonoids that are associated with better health outcomes can help develop nutritional recommendations for intervention studies and public health efforts.
About the study
In the current study, researchers determined the relationships between flavonoid consumption, flavonoid subcategories, and dementia risk. They also examined these relationships between genetically susceptible, hypertensive and depressed individuals.
The researchers analyzed dietary data from British Biobank participants aged 40 to 70, recruited between 2006 and 2010 from National Health Service (NHS) registers. Participants completed the Oxford WebQ nutritional questionnaire and completed several biological and physical assessments. All participants provided at least two dietary data. The 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 flavonoid score by summing the intakes of the major contributors to the flavonoid subclasses, and then estimated the cumulative average based on the participants’ energy intake. The top contributors were the three meals that consumed the most of each flavonoid subclass. The study exposures were adherence to the flavonoid diet score and flavonoid subclass consumption as measured by 24-hour dietary assessments.
The primary outcome measure was early-onset dementia and its relationship with hypertension, depression and genetic risk. Individuals carrying the apolipoprotein E (APOE) ε4 genotype or those in the top 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 identified dementia using the International Classification of Diseases, Ninth Revision (ICD-9) and ICD-10 codes. The censoring dates for mortality data were March 31, 2021 (Scotland and England) and February 28, 2018 (Wales). Researchers followed participants for nine years until the censoring date, dementia diagnosis, or death, whichever came first.
Multivariate Cox proportional hazards regressions determined the adjusted hazard ratios (AHR) for analysis. Study covariates included gender, 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 products. dietary index (hPDI) scores. Researchers analyzed data between September 1 and 30, 2023.
Results
Among the 121,986 individuals, the average age was 56 years; 56% were female, 97% were white and 882 developed dementia. Individuals in the quintile with the highest flavodiet score were more physically active with lower BMI values and less socio-economically disadvantaged than those in the lowest quintile. Comparing the top quintile to the bottom quintile for flavodiet scores, consuming six additional servings of flavonoid-rich items daily was related to a lower risk of dementia in study participants (AHR, 0.7), genetically susceptible individuals (AHR, 0.6) and those experiencing depression (AHR). , 0.5).
The researchers observed the highest risk reduction in individuals who consumed at least two of the three daily: five servings of tea, 0.5 servings 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 main contributors, supported the results, with inverse relationships with dementia incidence.
Sensitivity analyzes of individuals aged 60 or older followed for more than five years, and those with no history of stroke yielded similar results. The analyzes included genetically vulnerable whites and less educated and less physically active individuals living in highly socio-economically disadvantaged regions. Removing hPDI scores did not change the results.
Conclusion
The study found that increasing consumption of foods and drinks rich in flavonoids can reduce the incidence of dementia, especially in people who are genetically vulnerable, suffer from depression or have high blood pressure. 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, especially in high-risk groups. Tea showed the highest association with a reduced risk of dementia due to epicatechin, a flavonoid that inhibits the pathological effects of APOE.