Are psoriasis severity and comorbidities associated with diet quality? A cross-sectional analysis using UK Biobank

Psoriasis has been linked to various diet-related comorbidities such as metabolic syndrome, type 2 diabetes, and cardiovascular disease. Evidence is lacking on the role of diet in the management of psoriasis and its comorbidities. We aimed to characterise the dietary patterns and quality of diet in individuals living with psoriasis and to assess whether psoriasis severity and comorbidities are associated with diet quality.

Using the UK Biobank cohort, individuals identified with psoriasis via self-report and/or linked health records at baseline were compared with participants without psoriasis. Dietary intake was assessed through online 24 h-recalls (Oxford WebQ) conducted every 3-4 months over one year. Average nutrient and food group intakes were calculated from at least two 24 h dietary recalls to determine adherence to national food-based dietary guidelines (Eatwell Score (EWS), range: 0-9) and the Mediterranean-style diet (alternative Mediterranean diet (aMED) score, range: 0-9). Associations between psoriasis severity (using treatment category as a proxy), the presence of major comorbidities and diet quality scores were evaluated using regression models adjusting for covariates.

Among 2613 people with psoriasis (mean age 56.5, 49.6 % women) and 120,555 people without psoriasis (mean age 56.2, 56.2 % women), both groups had similar average scores for EWS (3.9 ± 1.7 for both groups). The psoriasis group had a slightly higher aMED score (4.4 ± 1.8 and 3.8 ± 1.7, P < 0.001). However, participants with psoriasis also reported higher intake of red and processed meat, sodium, free sugars, and alcohol (all P < 0.05) compared to the non-psoriasis group. Within the psoriasis group, no significant difference in diet quality was found between different clinical severities of psoriasis, but participants with the highest severity had lower odds of meeting guidelines for daily fruit and vegetable intakes (odds ratio (OR) 95 % confidence interval (CI): 0.69 (0.48, 0.98), P = 0.040) and scoring on nuts intake (OR (95 % CI): 0.66 (0.44, 1.00), P = 0.050) compared to those not receiving treatment. Participants in the psoriasis group with at least one comorbidity had significantly lower diet quality scores (EWS, beta (95%CI): -0.184 (-0.354, -0.014), P = 0.034; aMED beta (95%CI): -0.266 (-0.442, -0.089), P = 0.003).

Participants with psoriasis showed slightly better adherence to a Mediterranean-style diet but also consumed more processed meat, sodium, free sugars, and alcohol. Those with the most severe psoriasis or comorbidities had poorer diet quality, highlighting the opportunity for dietary interventions in this population.