Dietary macronutrient sources, particularly plant-based foods, are associated with reduced psoriasis severity, according to a recent study, with potential implications for adjunctive dietary counselling.

Conducted by researchers from King’s College London, the Asking People with Psoriasis about Lifestyle and Eating (APPLE) study aimed to assess the macronutrient intakes of people living with psoriasis in the UK and explore associations between dietary sources of these nutrients and disease severity.

Data were collected via an online cross-sectional survey using a Food Frequency Questionnaire and the self-assessed Simplified Psoriasis Index.

A total of 257 adults with psoriasis were included in the final analysis. Participants had a median age of 40 years and were predominantly female (82.5%) and of white-British ethnicity (84.8%).

Disease severity was distributed across mild (24.1%), moderate (44.7%) and severe (31.2%) categories. Approximately 51% of participants were overweight or had obesity.

Macronutrient sources and psoriasis severity

Overall, participants reported higher-than-recommended intakes of free sugars (median 11.2% of total energy) and inadequate fibre intake (20.2 g/day), with 78.2% failing to meet UK dietary fibre recommendations.

Free sugar intake was positively correlated with psoriasis severity (r=0.161, P=0.010), while fibre intake showed an inverse association (r=−0.183, P=0.003).

When examining dietary sources, higher proportions of free sugars from beverages were associated with increased odds of severe psoriasis (OR 3.85, 95% CI 1.507–9.831), although this relationship was attenuated after adjustment for body mass index (BMI).

A greater intake of protein from total meat was linked to higher odds of severe disease (OR 2.47, 95% CI 0.984–6.196), whereas protein from plant-based sources was inversely associated with severity (OR 0.36, 95% CI 0.140–0.915). Similar patterns were observed for fibre and n-6 polyunsaturated fatty acids, where plant-derived sources were associated with lower severity.

The authors concluded that the source of macronutrients, rather than total intake alone, was associated with disease severity and that dietary modification, particularly increasing plant-based nutrient sources, may have a role as an adjunct to psoriasis management as these were linked to more favourable outcomes.

These findings reinforce existing guidance emphasising weight management in psoriasis due to the observed associations between diet, body mass index (BMI) and disease severity.

Randomised controlled trials required

However, the evidence should be interpreted cautiously, as the cross-sectional design precludes causal inference, and the reliance on self-reported dietary intake and disease severity introduced potential recall and reporting bias.

Convenience sampling and incomplete responses may also have limited generalisability, the authors added, while differences in dietary assessment methods compared with national survey data may have affected comparisons.

While randomised controlled trials are required to confirm the findings, they suggested that prioritising plant-based dietary sources may be beneficial in psoriasis management.

The evidence supports integrating general dietary optimisation such as reducing free sugars, particularly from sugar-sweetened beverages, improving fibre intake and encouraging the consumption of plant-based foods, into holistic psoriasis care, while recognising the absence of definitive interventional data.

Future research into macronutrients and psoriasis should explore longitudinal relationships and incorporate objective dietary and biomarker assessments to better understand the role of diet in psoriasis progression, the authors said.

Reference
Zanesco S et al. Macronutrient intakes and associations with psoriasis severity: a cross-sectional analysis of the Asking People with Psoriasis about Lifestyle and Eating (APPLE) study. Eur J Nutr 2026;65:64.