RESUMO
Gastro-esophageal reflux disease [GERD] has become very common in the past three decades. The reason for this, as well as its exact pathophysiologic mechanisms are yet unknown. In this ecologic study we assessed the relation between water nitrate content and prevalence of GERD in Tehran, Iran. We determined the prevalence of acid regurgitation [AR] heartburn or any of them occurring on a frequent [at least weekly] or infrequent basis in areas with different water nitrate. The areas for nitrate were defined as below: <50mg nitrate/L, 50 - 74 mg/L, 75-100 mg/L, and >100 mg/L. Frequency of each symptom was assessed in each area and compared. Adjustment for age, sex, education, NSAID-consumption, BMI, smoking, history of GERD in first degree relatives and spouse was done in a multivariate model. People living in areas with water nitrate content more than 100mg/L had a higher chance of suffering from frequent AR than those living in areas with water nitrate less than 100mg/L [25.5% vs. 12.0%, OR: 2.53, 95% Cl: 1.36 - 4.73, P=0.006]. After adjustment for the named factors, the relationship remained significant [OR: 3.65, 95% Cl: 1.32 - 10.09]. The relation for frequent heartburn or infrequent symptoms was not significant. In this ecologic study, we found relation between experiencing frequent AR and drinking or cooking with water containing more than 100mg nitrate/L. Considering our current knowledge, if we put dietary nitrate into the puzzle of increased prevalence and/or pathophysi-ology of GERD, it can theoretically answer several questions. Hence we propose a nitrate-hypothesis for GERD pathogenesis