Abstract
OBJECTIVE: To explore the relationship between ultra-processed food (UPF) intake and knee osteoarthritis (KOA)-related imaging and clinical outcomes in men and women. DESIGN: Osteoarthritis Initiative participants with sufficient dietary and sociodemographic data (n = 4403) were included in this cross-sectional study. UPF was assessed by food frequency questionnaire-based NOVA Classification, categorizing diet according to processing level, with NOVA-4 indicating UPF. The exposure variable was standardized UPF proportion/day (%)-the proportion of NOVA-4 servings in the daily diet. The outcomes were Western Ontario and McMaster University OA Index (WOMAC) pain, activities of daily living (ADL), stiffness, total scores, average cartilage thickness (quantified using 3D-dual echo steady-state sequences on 3T MRI), Chair Stand Test (CST) and gait speed. Mixed effects and linear regression models were used for knee-level and participant-level outcomes, respectively. Models were adjusted for age, race, BMI, daily calories, physical activity, and medical insurance availability. Sex differences were tested by interactions between UPF and sex. RESULTS: Sex interactions were significant for WOMAC-pain, ADL, total, gait speed, cartilage thickness (p-interaction-range < 0.001-0.006). Greater UPF was associated with significantly worse pain (β = 0.17 [0.093, 0.242], p < 0.001), ADL (β = 0.59 [0.365, 0.832], p < 0.001), total scores (β = 0.81 [0.483, 1.13], p < 0.001), thinner cartilage (β = -0.013 [-0.02, -0.006], p < 0.001), slower gait (β = -0.035 [-0.042, -0.027], p < 0.001) in women. Sex interactions were non-significant for CST and WOMAC-stiffness (p-interaction = 0.319, 0.573, respectively). With greater UPF, CST and WOMAC-stiffness showed significant poor outcomes (β = -0.008 [-0.013, -0.004], p < 0.001, β = 0.04 [0.008, 0.064], p = 0.011, respectively). WOMAC-stiffness results were not significant after Bonferroni corrections. CONCLUSIONS: UPF-rich diet is linked to worse KOA outcomes disproportionately more in women.