Association between Dietary Intakes of Nitrate and Nitrite and the Risk of Hypertension and Chronic Kidney Disease: Tehran Lipid and Glucose Study

Background and Aim: The association of habitual intakes of dietary nitrate (NO(3)(−)) and nitrite (NO(2)(−)) with blood pressure and renal function is not clear. Here, we investigated a potential effect of dietary NO(3)(−) and NO(2)(−) on the occurrence of hypertension (HTN) and chronic kidney disease (CKD). Methods: A total of 2799 Iranian adults aged ≥20 years, participating in the Tehran Lipid and Glucose Study (TLGS), were included and followed for a median of 5.8 years. Dietary intakes of NO(3)(−) and NO(2)(−) were estimated using a semi-quantitative food frequency questionnaire. Demographics, anthropometrics, blood pressure and biochemical variables were evaluated at baseline and during follow-up examinations. To identify the odds ratio (OR) and 95% confidence interval (CI) of HTN and CKD across tertile categories of residual energy-adjusted NO(3)(−) and NO(2)(−) intakes, multivariate logistic regression models were used. Results: Dietary intake of NO(3)(−) had no significant association with the risk of HTN or CKD. Compared to the lowest tertile category (median intake < 6.04 mg/day), the highest intake (median intake ≥ 12.7 mg/day) of dietary NO(2)(−) was accompanied with a significant reduced risk of HTN, in the fully adjusted model (OR = 0.58, 95% CI = 0.33–0.98; p for trend = 0.054). The highest compared to the lowest tertile of dietary NO(2)(−) was also accompanied with a reduced risk of CKD (OR = 0.50, 95% CI = 0.24–0.89, p for trend = 0.07). Conclusion: Our findings indicated that higher intakes of NO(2)(−) might be an independent dietary protective factor against the development of HTN and CKD, which are major risk factors for adverse cardiovascular events.