Source-specific dietary nitrate and nitrite intakes are differentially associated with the incidence of hypertension: Tehran Lipid and Glucose Study.

In the current study, we have investigated the association between dietary nitrate (NO3)/nitrite (NO2) intakes and the incidence of hypertension (HTN). This study included a total of 1576 men and women (mean age of 36.4 ± 11.7 and 39% men) in the third (2006-2008) phase of the Tehran Lipid and Glucose Study and were followed up until 2018-2022. At the beginning of the study, a semiquantitative food frequency questionnaire was applied to measure dietary intakes of NO3 and NO2. Multivariable-adjusted Cox proportional hazard models for multiple variables were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) of incidence of HTN across different quartiles of NO3 and NO2 dietary intakes. Median (interquartile range) daily intake of NO3 and NO2 were 465 (253) mg/d and 9.6 (4.8) mg/d, which were mostly derived from plant-based sources (95.4% and 55.8%, respectively). Participants in the highest quartile of total and plant-based NO₃ intake were associated with a significantly lower risk of HTN (HRQ4 vs. Q1= 0.46; 95% CI, 0.23-0.91; HRQ4 vs. Q1=0.44; 95% CI, 0.22-0.87, in total and plant-based sources, respectively). No significant association was found between animal-based NO₃ intake and HTN incidence. The highest quartile of plant-based NO₂ intake, compared to the lowest, was associated with a lower risk of HTN (HRQ4 vs. Q1 = 0.57; 95% CI, 0.31-0.99) and there was no significant association between animal-based NO₂ intake and the risk of HTN. Higher intakes of total and plant-based NO3 and NO2, compared with lower intakes, were significantly associated with a lower risk of HTN.