Psoriasis is a chronic, inflammatory skin condition characterized by red, scaly patches that can cause substantial discomfort and social stigma (1). Psoriasis significantly impairs the quality of life of those affected, particularly when co-existing with other conditions (1-2). Although diet has been linked to many psoriasis-associated conditions, including cardiovascular disease, obesity and type 2 diabetes (3), evidence-based dietary guidance for psoriasis is currently lacking, and the research supporting dietary interventions for psoriasis management remains limited. This study aimed to characterize dietary intake in individuals with psoriasis and assess associations with psoriasis severity and the risk of psoriasis-related comorbidities.

This study included the baseline data from the UK Biobank cohort, a prospective study with 502,000 adults aged 40-69 years at baseline (2006-2010). Participants with psoriasis at baseline were identified by self-reports or linked health records. Participants without psoriasis at baseline who remained free of the condition during follow-up were included as controls. Individuals with chronic infectious inflammatory disease such as HIV or chronic viral hepatitis were excluded from both groups. Diet was assessed using a touchscreen food frequency questionnaire (FFQ), covering 16 major food groups. Associations between frequency or amount of food intake and psoriasis severity (assumed from self-reported medication use: systemic treatment > topical treatment only > no related medication), risk of 13 common psoriasis comorbidities were evaluated using multivariable regression models, adjusted for confounders including age, sex, Townsend deprivation index, physical activity level, smoking, alcohol, supplement use and the reporting source of psoriasis.

Compared to those living without psoriasis (N=485,201), participants living with psoriasis (N=10,920) were more likely to report consuming processed meat (adjusted odds ratio (aOR)=1.28, 95% confidence interval: 1.15-1.42, P<0.001) and bread (aOR=1.20, 1.13-1.27, P<0.001). Psoriasis was associated with a lower likelihood of breakfast cereal use (aOR=0.82, 0.77-0.88, P<0.001). Moreover, higher weekly cheese intake and daily tea intake were associated with a reduced likelihood of more severe psoriasis (aOR= 0.97, 0.94-0.99, P=0.018; aOR=0.98, 0.96-1.00, P=0.011, respectively). Regarding comorbidities, frequent intakes of meat products were associated with higher odds of psoriasis-related comorbidities, such as chronic kidney disease (aOR=1.11, 1.02-1.21, P=0.021), type 2 diabetes (aOR=1.10, 1.02-1.19, P=0.010),), obesity (aOR= 1.05, 1.00-1.10, P=0.048), osteoporosis (aOR=1.14, 1.04-1.26, P=0.007) or depression (aOR=1.07, 1.001.15, P=0.040).

Our findings suggest that specific food groups are associated with the severity of psoriasis and its comorbidities, highlighting the importance of dietary management in mid-adulthood years. Further longitudinal and interventional studies are needed to confirm these associations and establish dietary guidelines for psoriasis management.