Association between Dietary Flavonoid Intake and the Likelihood of Frailty in Middle-Aged and Older Adults: A Population-Based Analysis from the National Health and Nutrition Examination Survey (NHANES)

Objectives: Flavonoids are of particular interest for their antioxidant property and anti-inflammatory, and a therapeutic potential for age-related diseases has been suggested. Frailty is becoming a global public health concern due to an increasingly aging population. We aimed to evaluate the association between dietary flavonoid intake and the likelihood of frailty in middle-aged and older adults. Design: A US nationally representative cross-sectional study. Setting: National Health and Nutrition Examination Surveys database. Participants: Of the 8159 adults aged 50 years and older. Measurements: This study used data from NHANES (2007-2010 and 2017-2018). Dietary flavonoid intake data were obtained from a 24-h recall interview. Frailty was measured using a 53-item frailty index (FI) and diagnosed as FI > 0.21. We used survey-weighted logistic regression models to assess the association between flavonoid intake and odds of having frailty. The dose-response association between flavonoid intake and frailty was estimated using a survey-weighted restricted cubic spline (RCS) model. Results: Among the 8159 adults (63.42 +/- 0.20 years), 2551 (31.3%) had frailty. The RCS depicted a U-shaped association between total flavonoid intake and frailty. Compared with those in the lowest quintile (<= 14.55 mg/day), participants in the fourth total flavonoid intake quintile (84.13-313.51 mg/day) had the lowest likelihood of frailty with an OR (95% CI) of 0.65 (0.51-0.84). The likelihood of frailty decreased until 220 mg/day, with 2% (0.8%-4.1%) lower odds of frailty per 10 mg higher total flavonoid intake, which increased thereafter. Similarly, the U-shaped relation with frailty was observed for five flavonoid subclasses (flavan-3-ols, flavanones, flavones, flavonols, isoflavones), while a roughly negative linear relation was observed for the other flavonoid subclass (anthocyanidins). Conclusion: U-shaped associations with frailty for dietary intake of total flavonoids and flavonoid subclasses (flavan-3-ols, flavanones, flavones, flavonols, and isoflavones) were observed in middle-aged and older US adults.