title: Vitamin C intake modify the impact of dietary nitrite on the incidence of type 2 diabetes: A 6-year follow-up in Tehran Lipid and Glucose Study.
abstract: BACKGROUND
  There is no epidemiological study on the association between dietary nitrate (NO3) and nitrite (NO2) and intakes and the risk of type 2 diabetes (T2D).
  
  
  OBJECTIVE
  The aim of this study was therefore to examine the potential effect of dietary NO3and NO2on the occurrence of T2D.
  
  
  METHODS
  This longitudinal study was conducted within the framework of the Tehran Lipid and Glucose Study (TLGS) on 2139 T2D-free adults, aged 20-70 years, followed for a median of 5.8 y. Dietary intakes of NO3and NO2were estimated using a 168-food items validate semi-quantitative food frequency questionnaire, at baseline. Multivariate Hazard Ratios (HR) and 95% confidence intervals (CI), adjusted for diabetes risk score (DRS), and dietary intakes of fat, fiber and vitamin C, were calculated for residual energy-adjusted NO3and NO2intakes. Since significant interaction (P = 0.024) was found between NO2and vitamin C intakes in the multivariable model, stratified analyses were done for < and ≥ median vitamin C intakes.
  
  
  RESULTS
  Median (inter quartile range; IQR) daily intake of NO3and NO2were 410 mg/d (343-499) and 8.77 mg/d (7.53-10.2). An increased risk of T2D was observed among participants who had higher intake of total and animal-based NO2in participants who had low vitamin C intake (HR = 2.43, 95% CI = 1.45-4.05, HR = 1.88, 95% CI = 1.12-3.15, respectively). We found no significant association between NO3in overall, and plant- and animal sources as well, with the risk of T2D. Plant-derived NO2was also unrelated to incidence of T2D.
  
  
  CONCLUSIONS
  Our findings indicated that higher intakes of total and animal-based NO2may be an independent dietary risk factor for development of T2D in subjects with lower vitamin C intakes.
authors.affiliation: Nutrition and Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Bahadoran
authors.affiliation: Nutrition and Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Parvin
authors.initials: P
authors.lastname: Mirmiran
authors.affiliation: Endocrine Physiology Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Asghar
authors.initials: A
authors.lastname: Ghasemi
authors.affiliation: Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Mattias
authors.initials: M
authors.lastname: Carlström
authors.affiliation: Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Fereidoun
authors.initials: F
authors.lastname: Azizi
authors.affiliation: Prevention of Metabolic Disorders Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Iran. Electronic address: fzhadaegh@endocrine.ac.ir.
authors.forename: Farzad
authors.initials: F
authors.lastname: Hadaegh
mesh_terms: D000328:Adult; D000368:Aged; D001205:Ascorbic Acid / Q000008:administration & dosage*; D001786:Blood Glucose / Q000032:analysis; D003924:Diabetes Mellitus, Type 2 / Q000139:chemically induced / Q000453:epidemiology / Q000517:prevention & control*; D019587:Dietary Supplements; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007492:Iran / Q000453:epidemiology; D008137:Longitudinal Studies; D008875:Middle Aged; D009566:Nitrates / Q000008:administration & dosage; D009573:Nitrites / Q000009:adverse effects*; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D009566:Nitrates; D009573:Nitrites; D001205:Ascorbic Acid
keywords: Nitrate; Nitrite; Type 2 diabetes; Vitamin C