Dose–response relationship between dietary antioxidant intake and diabetic kidney disease in the US adults with diabetes

Aim The effects of dietary antioxidants on numerous diseases have been widely studied. However, the evidence regarding composite dietary antioxidant index (CDAI) and diabetic kidney disease (DKD) in individuals with diabetes is scarce. This study aimed to investigate the associations of CDAI with DKD and mortality in adults with diabetes mellitus (DM). Methods This study utilized data from 5676 adult DM participants from the National Health and Nutrition Examination Survey (NHANES) of 2007–2018. The study followed up on death outcomes by linking the data to records from the National Death Index until December 31, 2019. CDAI was evaluated using a well-established method that included six food-sourced antioxidants derived from 24-h dietary recall: selenium, zinc, vitamin A, vitamin C, vitamin E and carotenoids. The regression models were used to estimate the relationships of CDAI with DKD and mortality in diabetic individuals. Results The weighted mean CDAI level for the 5676 participants, which represented 31.36 million noninstitutionalized residents of the US, was 0.33. Based on CDAI quartiles, participants were classified into four groups. CDAI levels were significantly associated with age, gender, race, physical activity, estimated glomerular filtration rate and the prevalence of albuminuria, DKD and hyperuricemia. DKD occurred in 36.44% of diabetic participants, and higher CDAI levels were independently associated with a lower risk of DKD (OR 0.74, 95%CI 0.59–0.94, p for trend = 0.004) in diabetic individuals after multivariate adjustment. During a median follow-up of 67 months (38–104 months), a total of 1065 (15.80%) diabetic individuals died from all causes. Diabetic individuals with higher CDAI levels (Q4) demonstrated a lower risk of all-cause mortality (HR 0.67, 95% CI: 0.52–0.86, p for trend = 0.01) after adjusting for age, gender and race. Conclusions Maintaining an adequate antioxidant diet, as reflected in higher CDAI levels, may lower the risk of DKD and mortality in diabetic individuals. These findings offer a promising approach to managing diabetes and highlight the potential of food-based antioxidants as a preventative measure. Further research is warranted to explore the underlying mechanism linking dietary antioxidants and DKD and mortality in diabetic individuals.