The risk of gastrointestinal cancer and nitrate intake due to vegetable consumption: A case-control study in Minab, Iran

Background: Nitrate (NO3) is a necessary element for plant growth, but its excessive use in agricultural products causes different health problems. This study aimed to investigate the relationship between NO3 concentrations in vegetables and the prevalence of gastrointestinal cancers in Minab city, Iran. Methods: This case-control study was conducted on 60 people with cancer as the case group and 120 healthy people as the control group in Minab city. Data were collected through a questionnaire and measuring NO3 concentration levels in vegetables. All samples were examined for NO3 by reverse-phase HPLC (RP-HPLC) method. Results: The concentration levels of NO3 in all vegetables ranged from 15.08 (onion) to 1143.55 mg/kg (spinach). There was no significant difference between the concentrations of NO3 in all vegetables among the different regions. The most common cancer in the case group was stomach cancer (61.7%). There was a significant difference between the amount of daily intake of NO3, through different vegetables, and the prevalence of gastrointestinal cancer between the case and control groups (P < 0.05). The results showed that increasing the consumption of vegetables increases the chance of getting gastrointestinal cancer (OR: 5.72; P < 0.001). Conclusion: According to the results, there is a significant relationship between the NO3 concentration in vegetables and the prevalence of gastrointestinal cancers in the studied areas. It is highly recommended to closely monitor the cultivation, fertilization, and spray process of agricultural products, and frequent monitoring of NO3 levels in fruits and vegetables.