Investigating of dietary nitrate and nitrite interaction and vitamin C and urinary and serum nitrate and nitrite levels: Tehran Lipid and Glucose Study

Abstract

Background and Aim: studies show that antioxidants prevent conversion of NO3/NO2 to nitrosamines compounds. tha aim of this study was to determine the potential effect of interaction between dietary intakes of vitamin C and NO3/NO2 on urinary and serum levels of NO3/NO2. Materials and Methods: This cross-sectional study included 251 adults aged >19 years was performed in the phase 6 of the Tehran Lipid and Glucose Study in 2015. Food intake was assessed using a semi-quantitative food frequency questionnaire. The average daily intake of nitrate and nitrite and vitamin C was estimated. Serum and urine levels of nitrate and nitrite were measured using the Grease method. In order to determine the effect of vitamin C on the interaction of nitrate and nitrite in urine and serum, linear regression test was used to modify the effects of confounders. Results: There was a significant correlation between intake of nitrate and its urine level, above the median level of vitamin C intake (B = 0/004, P-value = 0/004). Also, this correlation remained significant after adjusting for age, sex, body mass index, calorie intake (B = 0.03, P-value = 0/001). The effect of vitamin C interactions on nitrate intake and urine level in the adjusted model for nitrate and nitrite was also found to be significant (B = 0/003 P-value = 0/001). Conclusion: Increased intake of vitamin C significantly increases urinary excretion of nitrate and it is effective in the interaction between dietary intakes and urinary excretion of nitrate.