Incidence of non-Hodgkin lymphoma (NHL) has been rising worldwide, but the reasons are undefined. Dietary habits may play a role in the etiology of NHL by influencing the metabolic pathways of several cells of the immune system. This case-control study investigated the relation between food consumption and NHL risk. Between 1999 and 2002, we conducted a hospital-based case-control study on NHL in 2 areas of Italy. Cases were 190 patients (median age 58 years) with incident NHL admitted to specialized and general hospitals. Controls were 484 patients (median age 63 years) with acute non-neoplastic conditions admitted to the same hospitals network of cases. A validated food-frequency questionnaire was used to assess habitual diet 2 years before interview. Unconditional multiple logistic regression was used to estimate the odds ratios (OR) and the corresponding 95% confidence intervals (CI), with allowance for energy intake, according to the residual model. Consumption of highest versus lowest quartile of pasta/rice (OR 5 1.87, 95% CI: 1.04-3.36) and cheese (OR 5 1.66, 95% CI: 0.98-2.83) were associated with a significantly increased NHL risk. Inverse association was found for vegetables (OR 5 0.49, 95% CI: 0.28-0.87), fruits (OR 5 0.51, 95% CI: 0.30-0.85), and egg consumption (OR 5 0.59, 95% CI: 0.36-0.97). The association of pasta/rice was also supported by an increased risk of high glycemic load levels (OR 5 1.86, 95% CI: 1.04-3.32). In conclusion, our results suggested that diet could affect NHL risk. ' 2005 Wiley-Liss, Inc.Key words: case-control study; risk factors; non-Hodgkin lymphoma; diet; glycemic load Unlike most cancers whose mortality rates have been decreasing over the last 2 decades, non-Hodgkin lymphoma (NHL) incidence and mortality rates have been steadily increasing. Since the 1970s and the 1980s, an increasing NHL incidence rate of 3-4% per year has been observed worldwide, and these rises are greater in developed than in developing countries. 1,2 The reasons of such an increase are largely unknown, and include diagnostic improvements, changes in NHL classification, HIV/AIDS and other immunosuppressive conditions, 3 and other infectious agents. [4][5][6][7] Various occupational, environmental and chemical agents have also been analyzed as risk factors for NHL, 8,9 but none of these factors explain the recent rise in NHL rates.Functions and metabolic pathways of several cells of the immune system are known to depend on certain nutrients, 10 pointing to a possible role of diet in the etiology of NHL. 11 Since the late 1980s, at least 15 epidemiological studies have examined the role of diet and NHL. Five were hospital-based case-control studies [12][13][14][15][16] ; 6 were population-based case-control studies [17][18][19][20][21][22] ; 4 were cohort studies. [23][24][25][26] Among these, 1 epidemiological study found an increased risk of NHL associated with breads and cereals 17 ; 3 studies observed inverse associations, in particular for intake of whole-grain foods 12,14,21