Gluten intake and risk of psoriasis, psoriatic arthritis, and atopic dermatitis among United States women.

BACKGROUND: Associations between gluten intake and psoriasis, psoriatic arthritis, and atopic dermatitis are poorly understood. OBJECTIVE: To determine whether increased gluten intake is associated with incident psoriasis, psoriatic arthritis, and atopic dermatitis. METHODS: Cohort studies among women in Nurses' Health Study II. Food frequency questionnaires were used to calculate gluten content of participants' diet every 4 years (1991-2015 for psoriatic disease, 1995-2013 for atopic dermatitis). Disease outcomes were assessed by self-report and subsequently validated. Multivariable-adjusted Cox proportional hazards models were used to calculate hazard ratios and 95% confidence intervals for the association between gluten intake (quintiles) and psoriasis, psoriatic arthritis, and atopic dermatitis. RESULTS: We included 85,185 participants in the psoriasis analysis, 85,324 in the psoriatic arthritis analysis, and 63,443 in the atopic dermatitis analysis. Increased gluten intake was not associated with any of the outcomes (all P for trend >.05). Comparing highest and lowest gluten intake quintiles, the multivariable hazard ratios (95% confidence intervals) were 1.15 (0.98-1.36) for psoriasis, 1.12 (0.78-1.62) for psoriatic arthritis, and 0.91 (0.66-1.25) for atopic dermatitis. LIMITATIONS: No assessment of a strictly gluten-free diet. CONCLUSIONS: Our findings do not support the amount of dietary gluten intake as a risk factor for psoriasis, psoriatic arthritis, or atopic dermatitis in adult women.