The Nitrate Content of Commonly Consumed Agricultural Products Including Vegetables, Cereals, and Legumes in Iran

The excessive presence of nitrate in foodstuff can be potentially toxic and carcinogenic to humans. This is because about 80% of the nitrate that enters the human body comes from vegetables. Therefore, the present study determined the nitrate content in agricultural products commonly consumed by Iranians. A total of 222 samples of 19 different varieties of these products, including vegetables (171 samples), cereals (42 samples), and legumes (9 samples), were randomly collected from major grocery stores in different cities in Iran between September 22 and December 15, 2020. The methods of HPLC-UV were used to evaluate the nitrate content. The detection limits (L.O.D.) and limit of quantification (L.O.Q.) were 0.071 and 0.22 mg kg-1, respectively. As a result, the mean nitrate levels in the different samples varied from 1042.50 mg kg-1 in lettuce to 49.90 mg kg-1 in wheat. Potato also had a higher mean nitrate concentration than the standard level. In addition, products such as tomatoes, eggplant, spinach, herbs, and lettuce had significantly lower average nitrate concentrations than the typical values. Moreover, the average nitrate concentration was highest in the central region (492.7 mg kg-1). In contrast, the lowest average nitrate concentration was in the northern region (121.7 mg kg-1) (P < 0.05). Moreover, the highest average nitrate concentration (468.52 mg kg-1) was found in the vegetable group and the lowest in the cereal group (50.40 mg kg-1) (P < 0.05). Taken together, this information could allow the establishment of a database for the quantification of nitrate exposure and its risk-benefit determination in the Iranian population.