The nitrate content of fresh and cooked vegetables and their health-related risks

Autoři: Hamzeh Salehzadeh aff001;  Afshin Maleki aff002;  Reza Rezaee aff002;  Behzad Shahmoradi aff002;  Koen Ponnet aff003
Působiště autorů: Student Research Committee, Kurdistan University of Medical Sciences, Sanandaj, Iran aff001;  Environmental Health Research Center, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran aff002;  Faculty of Social Sciences, imec-mict-Ghent University, Ghent, Belgium aff003
Vyšlo v časopise: PLoS ONE 15(1)
Kategorie: Research Article
doi: 10.1371/journal.pone.0227551



Vegetables are the most important source of nitrates in the human diet. During various processes in the body, nitrates are converted into nitrites, which causes various diseases, such as blue baby syndrome and cancer. This study aimed to determine the concentration of nitrates in several vegetable farms in Sanandaj city and to evaluate their health-related risks.


This descriptive cross-sectional study was conducted from October 2017 to July 2018. A total of 90 samples were taken from nine farms. Soil and water sampling was also carried out. All stages of sample preparation and extraction were carried out according to Food Standards 2–16721, and the nitrate measurements were performed using ion chromatography (Compact IC Plus 882 Model, Metrohm, Switzerland). A health risk assessment was performed using the non-carcinogenic risk assessment.


This study’s results showed that the nitrate concertation in all vegetables was less than National Iranian Vegetable Nitrate Standard. Nitrate levels in leafy vegetables were higher than in root vegetables, and the root vegetables levels were higher than those in Fruit vegetable. The nitrate level in vegetables in autumn was higher than in spring. The cooking process reduced the raw vegetables’ nitrate content from 4.094% to 13.407%, while the frying process increased the vegetables’ nitrate content from 12.46% to 29.93%. The highest health risk level in raw, cooked and fried vegetables was parsley, parsley and beet leaves, respectively, and the lowest in all categories was tomatoes. Generally, the highest health risk was related to fried beet leaves, and the lowest was raw tomatoes. In addition, each of the abovementioned relationships between vegetables’ nitrate levels and the harvest season, type of processing procedure and type of vegetables was significant (p < 0.05). The irrigation water’s nitrate concentration in all fields was between 12.36 and 33.14 mg/l. The soil contained nitrate levels of between 4.35 and 9.7 mg/kg.


Based on this study, we can conclude that the amount of nitrates in raw vegetables was lower than the standard limit’s level and that this level does not cause health problems for consumers.

Klíčová slova:

Brassica – Farms – Leaves – Nitrates – Radish – Spring – Tomatoes – Vegetables


1. Sadeghi E, Sharafi K, Almasi A, Dayhim M, Azizi E, Ghayebzadeh M. Study on the nitrite and nitrate levels changes by drying and frying processing in vegetables. Iranian Journal of Health and Environment. 2015;7(4):491–8.

2. Cammack R, Joannou C, Cui X-Y, Martinez CT, Maraj SR, Hughes MN. Nitrite and nitrosyl compounds in food preservation. Biochimica et Biophysica Acta (BBA)-Bioenergetics. 1999;1411(2–3):475–88.

3. Merusi C, Corradini C, Cavazza A, Borromei C, Salvadeo P. Determination of nitrates, nitrites and oxalates in food products by capillary electrophoresis with pH-dependent electroosmotic flow reversal. Food Chemistry. 2010;120(2):615–20.

4. Hsu J, Arcot J, Lee NA. Nitrate and nitrite quantification from cured meat and vegetables and their estimated dietary intake in Australians. Food Chemistry. 2009;115(1):334–9.

5. Chou S-S, Chung J, Hwang D. A high performance liquid chromatography method for determining nitrate and nitrite levels in vegetables. Journal of Food and Drug Analysis. 2003;11(3):233–8.

6. Dich J, Järvinen R, Knekt P, Penttilä PL. Dietary intakes of nitrate, nitrite and NDMA in the Finnish Mobile Clinic Health Examination Survey. 1996.

7. Boroujerdnia M, Ansari NA, Dehcordie FS. Effect of cultivars, harvesting time and level of nitrogen fertilizer on nitrate and nitrite content, yield in Romaine lettuce. Asian Journal of Plant Sciences. 2007.

8. Pavlou GC, Ehaliotis CD, Kavvadias VA. Effect of organic and inorganic fertilizers applied during successive crop seasons on growth and nitrate accumulation in lettuce. Scientia Horticulturae. 2007;111(4):319–25.

9. Ayaz A, Topcu A, Yurttagul M. Survey of nitrate and nitrite levels of fresh vegetables in Turkey. J Food Technol. 2007;5(2):177–9.

10. Prasad S, Chetty AA. Nitrate-N determination in leafy vegetables: Study of the effects of cooking and freezing. Food Chemistry. 2008;106(2):772–80.

11. Ward MH, DeKok TM, Levallois P, Brender J, Gulis G, Nolan BT, et al. Workgroup report: Drinking-water nitrate and health-recent findings and research needs. Environmental health perspectives. 2005:1607–14. doi: 10.1289/ehp.8043 16263519

12. Hord NG, Tang Y, Bryan NS. Food sources of nitrates and nitrites: the physiologic context for potential health benefits. The American journal of clinical nutrition. 2009;90(1):1–10. doi: 10.3945/ajcn.2008.27131 19439460

13. Bell R, Davies R, Howard E. The changing structure of food retailing in Europe: the implications for strategy. Long Range Planning. 1997;30(6):853–61.

14. Gholami A, Keley K, Alavi SA. A study of nitrate contamination in soil and vegetables in dezful. 2013.

15. Tabande L, Taheri M. Evaluation of Exposure to Heavy Metals Cu, Zn, Cd and Pb in Vegetables Grown in the Olericultures of Zanjan Province's Fields. Iranian Journal of Health and Environment. 2016;9(1):41–56.

16. hanafi, hatami. Preparation of climate map of Kurdistan province using GIS. Sepehr Geographical Information Journal. 2013;22(87):24–8.

17. Shokatyari S, Heidari R, jamei r, Hosseini Sarghein S. The study of effects of some characteristics of the soil habitat on total alkaloids in Leontice leontopetalum and L. Armeniaca tubers from four different regions of Iran. Materials & Energy. 2013;13(1):737–48.

18. Farahani SS, Rajabipour A, Keyhani A, Sharifi M. Energy use and economic analysis of NPK-15: 8: 15 fertilizer granulation process in Iran. Journal of the Saudi Society of Agricultural Sciences. 2017;16(3):265–9.

19. Khoshtinat K, Pourmoghim M, Maki A, Fenoud R, Pirali M. Determine the Concentration of Nitrate in Lettuce, Tomatoes and Potatoes Marketed in the Tehran Fruits and Vegetables by HPLC. Journal of Food Science and Technology Iran. 2009;10:63–75.

20. Wood R III. A comparison of the extraction methods used in the UK nitrate residues monitoring program. Journal of the Association of Public Analysts (Online). 2006;34:1–11.

21. Molina V. Health risk assessment of selected heavy metals bioaccumulation in Laguna de Bay [Philippines] fish products. 2011.

22. Mehrabi Z, Eshghizadeh HR, Nematpour A. Evaluation of nitrate concentration in soil, groundwater and potato tubers on different farm size levels in Fereidan city of Isfahan. JWSS-Isfahan University of Technology. 2017;21(1):1–12.

23. Tamme T, Reinik M, Roasto M, Juhkam K, Tenno T, Kiis A. Nitrates and nitrites in vegetables and vegetable-based products and their intakes by the Estonian population. Food additives and contaminants. 2006;23(4):355–61. doi: 10.1080/02652030500482363 16546882

24. Authority EFS. Nitrate in vegetables-Scientific Opinion of the Panel on Contaminants in the Food chain. EFSA Journal. 2008;6(6):689.

25. Bill H. To: HEYDENS, WILLIAM F [AG/1000] Subject: FW: summary article.

26. Shahbazzadegan S, Hashemimajd K, Shahbazi B. Determination of nitrate concentration of consumed vegetables and fruits in Ardabil. Journal of Ardabil University of Medical Sciences. 2010;10(1):38–47.

27. Tabande L, Safarzadeh Shiraze S. Evaluation of nitrate accumulation and factors affecting it in some leafy vegetables in Zanjan Province. Iranian Journal of Soil Research. 2018;32(2):189–202.

28. Fytianos K, Zarogiannis P. Nitrate and nitrite accumulation in fresh vegetables from Greece. Bulletin of environmental contamination and toxicology. 1999;62(2):187–92. doi: 10.1007/s001289900858 9933316

29. Pretty JN, Brett C, Gee D, Hine R, Mason C, Morison J, et al. An assessment of the total external costs of UK agriculture. Agricultural systems. 2000;65(2):113–36.

30. Pirsaheb M, Rahimian S, Pasdar Y. Nitrite and Nitrate content of fruits and vegetables in Kermanshah (2010). 2012.


32. Hmelak Gorenjak A, Cencič A. Nitrate in vegetables and their impact on human health. A review. Acta alimentaria. 2013;42(2):158–72.

33. Pate J. Transport and partitioning of nitrogenous solutes. Annual Review of Plant Physiology. 1980;31(1):313–40.

34. BLOM-ZANDSTRA M. Nitrate accumulation in vegetables and its relationship to quality. Annals of Applied Biology. 1989;115(3):553–61.

35. Santamaria P. Nitrate in vegetables: toxicity, content, intake and EC regulation. Journal of the Science of Food and Agriculture. 2006;86(1):10–7.

36. Bakr TMA, El-Iraqui S, Huissen MH. Nitrate and nitrite contents of some fresh and processed Egyptian vegetables. Food Chemistry. 1986;19(4):265–75.

37. Bednar C, Kies C. Nitrate and vitamin C from fruits and vegetables: Impact of intake variations on nitrate and nitrite excretions of humans. Plant foods for human nutrition. 1994;45(1):71–80. doi: 10.1007/bf01091231 8146105

38. Williams GM, Aardema M, Acquavella J, Berry SC, Brusick D, Burns MM, et al. (2016) A review of the carcinogenic potential of glyphosate by four independent expert panels and comparison to the IARC assessment. Critical Reviews in Toxicology. 2016;46(sup1):3–20. doi: 10.1080/10408444.2016.1214677 27677666

39. Pourmoghim M, Khoshtinat K, Makkei A, Fonod R, Golestan B, Pirali M. Determination of nitrate contents of lettuce, tomatoes and potatoes on sale in Tehran central fruit and vegetable market by HPLC. Iranian Journal of Nutrition Sciences & Food Technology. 2010;5(1):63–70.


41. Ramachandran A, Hrycan W, Bantle J, Waterer D. Seasonal changes in tissue nitrate levels in fall-planted spinach (Spinacia oleracea). Website: 2005.

42. Boroujerdnia M, Ansari NA, Dehcordie FS. Effect of cultivars, harvesting time and level of nitrogen fertilizer on nitrate and nitrite content, yield in Romaine lettuce. Asian J Plant Sci. 2007;6(3):550–3.

43. Shahlaei A, Ansari NA, Dehkordie FS. Evaluation of nitrate and nitrite content of Iran Southern (Ahwaz) vegetables during winter and spring of 2006. Asian J Plant Sci. 2007;6(1):97–12.

44. Sadeghi E, Hashemian A, Mohammadi M, Bohlouli Oskoii S, Meskini H, Mohammadi R, et al. Study on the effect of boiling and freezing process on nitrate and nitrite levels in abundant consumed vegetables. Iranian Journal of Nutrition Sciences & Food Technology. 2013;8(3):201–8.

45. Huarte-Mendicoa J, Astiasaran I, Bello J. Nitrate and nitrite levels in fresh and frozen broccoli. Effect of freezing and cooking. Food Chemistry. 1997;58(1–2):39–42.

46. Chetty AA, Prasad S. Flow injection analysis of nitrate-N determination in root vegetables: Study of the effects of cooking. Food Chemistry. 2009;116(2):561–6.

47. Hill MJ. Nitrates and nitrites in food and water: CRC Press; 1996.

48. Suh J, Paek OJ, Kang Y, Ahn JE, Jung JS, An YS, et al. Risk assessment on nitrate and nitrite in vegetables available in korean diet. Journal of Applied Biological Chemistry. 2013;56(4):205–11.

49. Gruszecka-Kosowska A, Baran A. Concentration and health risk assessment of nitrates in vegetables from conventional and organic farming. Human and Ecological Risk Assessment: An International Journal. 2017;23(4):727–40.

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2020 Číslo 1