Dietary nitrate and nitrite intake and risk of non-Hodgkin lymphoma

Although established risk factors such as immunodeficiency and viral infections may be responsible for a portion of cases of non-Hodgkin lymphoma (NHL), the vast majority of cases of NHL remain unexplained. The role of dietary nitrate and nitrite in NHL risk is of interest since they are precursors of N-nitroso compounds, and nitrosoureas have been shown to induce B- and T-cell lymphomas in animal studies. However, few studies have evaluated the potential association between consumption of nitrate and nitrite and NHL by subtype or chromosomal translocation status, and the results of these studies have been inconsistent. We estimated the dietary intake of nitrate and nitrite using a food frequency questionnaire in a population-based, case-control study of 348 cases and 470 controls conducted in Nebraska in 1999-2002. A non-significant excess risk of NHL was found among women who reported an intake of nitrite in the highest quartile compared to the lowest quartile (odds ratio [OR] = 1.6; 95% confidence interval [CI]: 0.8-2.9), particularly nitrite from animal sources (OR = 1.9; 95% CI: 1.0-3.4). No significant associations were observed for nitrate or nitrite by NHL subtype. Although there were some increases in risk that support the N-nitroso hypothesis, they were not significant and do not confer strong evidence of an association.