Total antioxidant capacity of the diet modulates the association between habitual nitrate intake and cardiovascular events: A longitudinal follow-up in Tehran Lipid and Glucose Study

Zahra Bahadoran, Mattias Carlström, Asghar Ghasemi, Parvin Mirmiran, Fereidoun Azizi, Farzad Hadaegh

Considering the lack of data on the association between habitual dietary intakes of nitrate (NO3-) and nitrite (NO2-) and cardiovascular events, we assessed possible effects of dietary NO3-and NO2-, in the context of total antioxidant capacity (TAC) of the diet, with the risk of cardiovascular (CVD) outcomes. Adult men and women without CVD (n = 2369) were recruited from the Tehran Lipid and Glucose Study and were followed for a mean of 6.7 years. Dietary NO3-and NO2-intakes, as well as dietary TAC and nitric oxide (NO) index were assessed at baseline (2006-2008). Multivariable-adjusted Cox proportional hazards regression models were used to estimate risk of CVD above and below median of dietary intakes of NO3-/NO2-and dietary TAC and NO index. Due to a significant interaction between NO3-/NO2-intake and TAC, stratified analyses were done for < and ≥ median dietary TAC. Daily mean (SD) dietary NO3-and NO2-intakes were 460 (195) and 9.5 (3.9) mg; mean (SD) dietary TAC and NO index was 1406 (740) and 338 (197) μmol trolox equivalent (TE)/100 g. In subjects with lower dietary TAC, higher intake of NO3-(≥ 430 mg/d) was accompanied with an increased risk of CVD (HR = 3.28, 95% CI = 1.54-6.99). There were no significant associations between dietary intakes of NO2-, TAC of the diet and NO index with the occurrence of CVD events during the study follow-up. High habitual intake of NO3-, in the context of low TAC of the food, may be associated with the risk of CVD outcomes.