Flavonoid-rich foods lower risk of frailty and mental decline in older adults

By Tarun Sai LomteReviewed by Susha Cheriyedath, M.Sc.May 14 2025

New research reveals that adding more flavonoid-rich foods like tea, berries, and citrus to your diet could help reduce frailty and support mental and physical health as you age.

Study: Associations between flavonoid-rich food and flavonoid intakes and incident unhealthy aging outcomes in older United States males and females. Image Credit: DIVA.photo / Shutterstock

In a recent study published in The American Journal of Clinical Nutrition, researchers examined the associations between the intake of flavonoids and flavonoid-rich foods and unhealthy aging. Aging occurs due to the accumulation of cellular and molecular damage, resulting in a gradual decline in mental and physical capabilities, elevated disease susceptibility, and eventual death. Despite life expectancy increases, the proportion of the added years spent in good health has been constant.

Notably, nutrition is an essential determinant of health in aging. Flavonoids are bioactive compounds in plant-based foods, drawing attention for their impact on healthy aging. Prior research has linked higher flavonoid intake to increased chances of healthy aging and a slowing of biological aging processes. Flavonoids are abundant in apples, tea, berries, citrus fruits, dark chocolate, and red wine, and exhibit oxidative stress-reducing, anti-inflammatory, and neuroprotective properties.

About the study

In the present study, researchers examined the associations between the intakes of flavonoids and flavonoid-rich foods and healthy aging indicators. They used data from the Health Professionals Follow-up Study (HPFS) and the Nurses’ Health Study (NHS). Participants in these cohorts completed medical history and lifestyle questionnaires at baseline and every subsequent two years.

Participants with missing data on dietary exposure and those with extreme energy intakes were excluded. Further, food frequency questionnaires (FFQs) were completed at baseline and every subsequent four years. Intake frequencies of flavonoid-rich foods were recorded as servings per day, week, or month.

Both changes in intake and time-updated intakes of the flavodiet score (FDS) and its components were calculated from the FFQs. The FDS, an aggregate intake of major flavonoid-rich foods and beverages (specifically tea, apples, oranges, grapefruits, blueberries, strawberries, and red wine), was developed as a composite measure that captures overall adherence to a diet rich in flavonoid-containing foods, providing a more holistic perspective and facilitating public health translation. Besides, time-updated intakes of total flavonoids and flavonoid subclasses were calculated from the FFQs. The study outcomes were frailty, poor mental health, and physical impairment.

Participants completed the Short-Form Health Survey (SF-36) every four years. Frailty was assessed from the SF-36 and defined as having at least three of the following: fatigue, poor strength, reduced aerobic capacity, having five or more chronic illnesses, and weight loss of at least 5%. Likewise, a 100-point physical function score was calculated based on responses to 10 SF-36 questions; a score below 80 indicated physical impairment.

Mental health was assessed using five SF-36 questions (MF-5), the Center for Epidemiologic Studies Depression Scale 10 in the NHS, and the 15 questions in the Geriatric Depression Scale 15 in both the NHS and HPFS. Poor mental health was defined as an MF-5 score of 52 or less, a CES-D 10 score of 10 or higher, or a GDS-15 score of 6 or higher. Cox proportional hazards models estimated associations with incident frailty, poor mental health, and physical impairment.

Findings

The study included 62,743 females from the NHS and 23,687 males from the HPFS. All participants were aged 60 or older. In the NHS, there were 11,369, 8,944, and 22,419 incident cases of frailty, poor mental health, and physical impairment, respectively, over 24 years of follow-up. In the HPFS, there were 1,957 incident cases of frailty, 4,165 of physical impairment, and 1,669 of poor mental health over 12 years of follow-up.

In the NHS, the highest FDSs were associated with a 15% reduced risk of frailty and a 12% reduced risk of poor mental health and physical impairment. The highest intakes of total flavonoids were associated with an 11% lower risk of poor mental health and physical impairment and a 14% lower risk of frailty. The highest intakes of apples, red wine, tea, oranges/orange juice, and blueberries were associated with an 11% to 21% lower risk of frailty than the lowest intakes.

The highest intakes of apples, blueberries, red wine, oranges/orange juice, and strawberries were associated with 4% to 14% reduced risk of physical impairment relative to the lowest intakes. Likewise, the highest intakes of strawberries, apples, grapefruit/grapefruit juice, and oranges/orange juice were associated with a 10% to 15% reduced risk of poor mental health compared to the lowest intakes.

In the HPFS, there were fewer associations. Moderate (quintile 4) intakes of total flavonoids were associated with a 12% lower risk of impaired physical function, although the highest flavodiet score intakes were associated with an 18% reduced risk of poor mental health. Further, moderate intakes of red wine (quartile 3) and the highest intakes of blueberries and tea were associated with 29%, 15%, and 14% reduced risk of poor mental health, respectively.

Conversely, intakes of any of the individual flavonoid-rich foods and beverages examined were not associated with either frailty or physical impairment or frailty in the HPFS. The highest intakes of each of the flavonoid subclasses were associated with 9%–17% lower risk of frailty, 8%–14% lower risk of impaired physical function, and 8%–23% lower risk of poor mental health (except for flavan-3-ol monomers, which were not associated with poor mental health) in the NHS. Consistently, fewer associations were observed in the HPFS; moderate (quintile 4) intakes of flavan-3-ol polymers were associated with a 12% lower risk of developing impaired physical function, while moderate (quintile 3 or 4) intakes of flavonols, flavan-3-ol polymers, and flavones, and high (quintile 5) intakes of anthocyanins were associated with 16%–25% lower risk of poor mental health.

FDSs that decreased by seven or more servings per week were associated with 7% and 18% higher risk of physical impairment and frailty in the NHS, respectively, and a 60% higher risk of poor mental health in the HPFS, compared to unchanged scores. Further, a three-servings-per-day increase in the FDS was associated with 8%, 7%, and 11% lower risk of poor mental health, physical impairment, and frailty, respectively, in the NHS, and a 15% lower risk of poor mental health in the HPFS.

Conclusions

In sum, habitually high and increasing FDSs were found to be associated with a modest reduction in the risks of frailty, poor mental health, and physical impairment in the NHS. Higher intakes of red wine, tea, oranges/orange juice, and blueberries also generally tended to be associated with a lower risk of these outcomes. However, there were fewer associations in the HPFS. The paper suggests that this might be attributed to factors such as the comparatively shorter follow-up time for males, resulting in fewer events and reduced statistical power, or differences in lifestyle factors like smoking prevalence, indicating that further studies are needed to better understand if there may be potential sex differences in the dietary risk factors for health in aging.

The authors also acknowledge several limitations, including reliance on self-reported data which could lead to misclassification, the potential for residual or unmeasured confounding factors, the challenge of isolating the effects of flavonoids from other food constituents, and a study population that was predominantly White, which may limit the generalizability of the findings to other groups.

Overall, the findings suggest that high intakes of flavonoid-rich foods may support healthy aging. From a public health perspective, the observation that a modest and achievable increase, such as three additional servings per day of flavonoid-rich foods, was associated with notably lower risks for these adverse aging outcomes in females (and for poor mental health in males) underscores the potential for simple dietary modifications to contribute to a healthier lifespan.