reported Alanna C. Bridgman of Queen’s University, Kingston, Ont., and her associates.
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In a large, retrospective cohort study among women from the Nurses’ Health Study II (NHS-II), including 85,185 psoriasis participants and 63,443 atopic dermatitis participants, Ms. Bridgman and her associates sought to determine whether proinflammatory diet increased the risk of incident psoriasis, psoriatic arthritis, or atopic dermatitis. Clinicians administered food frequency questionnaires every 4 years beginning in 1991 among female nurses aged 25-42 years.
Food groups included in the evaluation were those most predictive of three plasma markers of inflammation: interleukin-6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor–alpha R2 (TNF-R2). Proinflammatory foods included processed meat, red meat, organ meat, white fish, vegetables other than leafy green and dark yellow, refined grains, low- and high-energy drinks, and tomatoes. Anti-inflammatory foods included beer, wine, tea, coffee, dark yellow and green leafy vegetables, snacks such as popcorn and crackers, fruit juice, and pizza.
No association was found between proinflammatory diet and increased likelihood for incident psoriasis, psoriatic arthritis, or atopic dermatitis. Although proinflammatory dietary patterns were associated with psoriatic arthritis in the age-adjusted model, the hazard ratio was attenuated and found to be no longer statistically significant after adjustment for important confounders such as body mass index. In addition, no significant relationship between atopic dermatitis and proinflammatory diet was observed, they reported. The study was published in the Journal of the American Academy of Dermatology.
Ms. Bridgman and her associates measured dietary patterns using the Empirical Dietary Inflammatory Pattern (EDIP); dietary patterns measuring high on the EDIP scale were associated with higher levels of TNF-alpha, TNF-alpha R1, TNF-alpha R2, CRP, IL-6, and adiponectin. Psoriasis and psoriatic arthritis are Th1- and Th17-mediated diseases that exhibit higher serum levels of IL-6, CRP, and TNF-alpha, unlike atopic dermatitis, which is primarily a Th2-mediated condition featuring reduced involvement of the Th1/Th17 inflammatory cytokines.
Because a goal of the EDIP score was to “account for the overall effect of dietary patterns,” the researchers included in their analysis only those food groups that “explain the maximal variation in the three noted inflammatory biomarkers.”