High intake of dietary phytochemical index may be related to reducing risk of diabetic nephropathy: a case–control study

OBJECTIVE: Diabetic nephropathy (DN) is involved in 40% of patients with type 2 diabetes, Phytochemical index (PI) foods are known as antioxidant and anti-inflammatory agents. Higher intake of phytochemicals can improve glucose tolerance, hypertension and complications of DN. This study sought to discern the relationship between dietary PI and DN. METHODS: This was a case–control study which was conducted between 210 diabetic women. General characteristics, blood pressure, biochemical serum levels, and anthropometric measurements were evaluated. Physical activity and dietary intakes were assessed via short form of physical activity questionnaire and 147 items-validated food frequency questionnaires, respectively. Then, PI was calculated through method of McCarty and divided to 2 groups of lower and higher of median. Independent samples T tests were used to identify differences in quantitative variables. To investigate the relationship between dietary PI and risk of DN, logistic regression was used. The odds ratio (OR) of DN, and its 95% confidence interval (CI), in each groups of PI were shown. RESULTS: The percentage of daily intake of energy from fruits and vegetables were higher than the other sources of phytochemical rich foods. Higher consumption of vitamin A was seen in higher group of PI among the control group, after adjusting for energy intake. In the higher adherence of median of dietary PI group, intake of fruits, vegetables, legumes, grains, and olives of controls were higher than cases. In addition, soy consumption was statistically different between lower and higher adherence of median of dietary PI among cases. There was an inverse relationship between dietary PI and risk of DN (OR = 0.44; 95% CI: 0.25–0.77; P = 0.04). After adjusting for potential confounders, the association remained significant, albeit with lower odds of having DN (OR = 0.15; 95% CI: 0.06–0.36; P < 0.001). CONCLUSION: Finally, the present study found evidence indicating an inverse relationship between consumption of foods rich in phytochemicals and risk of DN in this sample. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40795-023-00676-2.