Higher dietary antioxidant quality is linked to reduced diabetic nephropathy risk in type 2 diabetes: a case-control study

Oxidative stress plays an important role in the pathogenesis of diabetic nephropathy (DN). The dietary antioxidant quality score (DAQS) indicates overall dietary antioxidant intake. We conducted this case-control study on 206 adults aged 18–65 with diabetes (103 cases with DN and 103 controls without DN) who attended the Labafinezhad clinic in Tehran, Iran, during 2023–2024. DN was defined as persistent albuminuria (≥ 30 mg/g creatinine) or reduced eGFR (< 60 ml/min/1.73 m 2 ). General characteristics were collected, and a food frequency questionnaire (FFQ) containing 147 items was used to assess dietary intakes. Data from dietary intakes of vitamins C, E, A, selenium, and zinc were used to evaluate DAQS. The associations between DAQS and DN were assessed by logistic regression models. An inverse association between DAQS and the odds of DN was found (OR: 0.667; 95% CI: 0.466–0.954; P = 0.027). This association was significant even after controlling for possible confounding variables, including sex, age, BMI, blood pressure, waist circumference, diabetes duration, smoking, physical activity, HbA1c, and hypertension medications. Our results may be used to develop potential dietary recommendations to delay diabetic nephropathy development and to use DAQS as a probable predictor of DN.