Dietary patterns and the risk of systemic lupus erythematosus in a Japanese population: The Kyushu Sapporo SLE (KYSS) Study

Background: Dietary factors are major regulators of immune function. As systemic lupus erythematosus (SLE) is a multisystem autoimmune disorder, dietary factors are probably associated with SLE risk. However, there are very limited studies on the association between SLE risk and diet. Methods: Factor analysis of 30 food items was performed to identify dietary patterns in 125 female SLE patients and 344 female controls. Dietary information was obtained by a self-administered food frequency questionnaire. Unconditional logistic regression was used to compute the odds ratios (ORs) and their 95% confidence intervals (CIs), with adjustments for several covariates. Results: We identified three dietary patterns: vegetable, meat and dairy product patterns. After adjustment for potential confounders, the dairy product pattern was significantly associated with an increased risk of SLE. Adjusted ORs (95% CI) for SLE in the first, second, third and fourth quartiles of the dairy product pattern were 1.00 (reference), 1.76 (0.89 - 3.54), 2.25 (1.15 - 4.43) and 1.97 (0.98 - 3.95), respectively (P_trend = 0.045). The other two dietary patterns were not associated with SLE risk. Conclusion: The dairy product pattern may be associated with an increased risk of SLE. Additional studies are warranted to confirm the findings suggested in this study.