Dietary Inflammatory Potential Not Associated With Psoriasis

Incident psoriasis is not associated with dietary inflammatory index (DII), according to study results published in the Journal of Dermatology.

Researchers used data from the National Health and Nutrition Examination Survey (NHANES) to assess the relationship between dietary inflammatory potential as measured with the DII and the risk for psoriasis. Data from 2003 to 2006 and 2009 to 2014 were obtained for patients with psoriasis aged 20 years and older.

Dietary information in the DII was based on a 24-hour dietary recall interview with validation and verification by the Nutrition Methodology Working Group. Among 45 food parameters, 26 were used to generate the DII, with a higher positive DII score indicating a greater proinflammatory dietary condition and vice versa.

A moderately adjusted model (model 2) included age group, sex, and race. A fully adjusted model (model 3) adjusted for age group, sex, race, energy and protein intake, education level, family income, body mass index, marital status, smoking status, physical activity, hypertension, and diabetes.

Researchers grouped DII into tertiles in regression analysis according to weighted distributions. The DII tertile 1 scores ranged from -4.64 to -1.02, DII tertile 2 scores ranged from -1.02 to 0.68, and DII tertile 3 scores ranged from 0.68 to 4.41.

A total of 13,284 participants were included in the study, 383 of whom had psoriasis (prevalence rate 2.88%; 95% CI, 2.61-3.18). Participants’ mean age was 48.94±17.71 years, and 49.53% were men.

In the unadjusted model 1, DII was not associated with psoriasis (odds ratio [OR], 0.99; 95% CI, 0.91-1.10), which was comparable with the fully adjusted model 3 (OR, 0.99; 95% CI, 0.89-1.11) according to weighted logistic regression analysis. In sensitivity analysis based on DII tertiles, the odds of psoriasis for patients in DII tertile 2 (OR, 0.75; 95% CI, 0.63-1.12) or tertile 3 (OR, 0.81; 95% CI, 0.51-1.28) remained insignificant compared with DII tertile.

Restricted cubic splines suggested that although the odds of psoriasis had slightly increasing trends with DII, no association was observed between DII and psoriasis in an overall or nonlinear manner. In subgroup analysis, no significant association was found between DII and psoriasis, with a low risk for heterogeneity (for interaction, P >.05).

Study limitations include causal inferences between DII and psoriasis that could not be obtained owing to the cross-sectional design, and the definition of psoriasis was based on medical questionnaires instead of clinical diagnosis (except for NHANES 2003-2004).

Researchers conclude, “Although a proinflammatory diet could lead to several health risks, the occurrence of psoriasis might not be associated with dietary inflammatory potential.”