Association of Dietary Quality With Risk of Incident Systemic Lupus Erythematosus in the Nurses’ Health Study and Nurses’ Health Study II

Objective Knowledge remains scarce regarding diet and systemic lupus erythematosus (SLE) risk. Our objective was to investigate 4 dietary quality scores and SLE risk overall and by anti–double‐stranded DNA (anti‐dsDNA) positive versus negative subtypes. Methods We studied 79,568 women in the Nurses’ Health Study (1984–2014) and 93,554 in the Nurses’ Health Study II (1991–2013). Using validated food frequency questionnaires, we calculated 4 dietary scores: the 2010 Alternative Healthy Eating Index (AHEI‐2010), the Alternative Mediterranean Diet Score (aMed), the Dietary Approach to Stop Hypertension (DASH), and the Empirical Dietary Inflammatory Pattern (EDIP). Incident SLE was confirmed by medical record review. Time‐varying Cox regression models estimated pooled hazard ratios (HRs) and 95% confidence intervals (95% CIs) of SLE risk, overall and by anti‐dsDNA, for cumulative average dietary quality score tertiles and individual AHEI‐2010 components. Results We identified 194 incident SLE cases. SLE risk was similar in women with the highest (versus lowest) dietary scores (AHEI‐2010 HR 0.78 [95% CI 0.54–1.14], aMed HR 0.82 [95% CI 0.56–1.18], DASH HR 1.16 [95% CI 0.81–1.66], EDIP HR 0.83 [95% CI 0.57–1.21]). No association was demonstrated for anti‐dsDNA+ or anti‐dsDNA– SLE risk. Women in the highest (versus lowest) AHEI‐2010 tertile of nut/legume intake had a decreased SLE risk (HR 0.59 [95% CI 0.40–0.87]). No association was demonstrated for other AHEI‐2010 components and SLE risk. Conclusion We observed no association between long‐term adherence to the AHEI‐2010, aMed, DASH, or EDIP scores with SLE risk, suggesting a large effect of dietary quality on SLE risk is unlikely. However, potential reduction in overall SLE risk with high nut/legume intake warrants further investigation.