Fig. 1

McMasters Universities (WOMAC) scores (total, pain, stiffness, and physical function) of patients with knee osteoarthritis across quartiles (Q) of dietary total antioxidant capacity. Data are shown as OR. The number of participants was 40 in each quartile. P-trend values were obtained from analysis of covariance (ANCOVA) with adjustment for age, sex, BMI, cigarette smoking, vitamin D and calcium supplement use, disease duration, physical activity, and energy intake. Quartile cut points of dietary TAC are as follows: first quartile, < 8.02; second quartile, 8.02–11.39; third quartile, 11.40–15.43; and fourth quartile, ≥ 15.44. P < 0.05 was considered significant