A plant-based diet may help ease psoriasis symptoms.

Psoriasis has long been considered not only a skin disease but also a condition associated with systemic inflammation and metabolic factors. Diet is one of the most widely discussed "modifiable" factors, but in real-world populations, the exact amount of protein, fat, carbohydrates, and fiber consumed by people with psoriasis, and from which foods, is rarely measured.

The European Journal of Nutrition published an analysis of the Asking People with Psoriasis About Lifestyle and Eating (APPLE) study: the authors assessed the diets of 257 adults with psoriasis in the UK and tested whether macronutrient sources were associated with symptom severity.

Background of the study

Psoriasis is a chronic inflammatory disease whose course varies greatly from person to person: some experience limited plaques and rare flare-ups, while others experience severe skin manifestations and accompanying psoriatic arthritis. Given this, it's natural to look for factors that may be "pushing" the inflammation up or down.

Nutrition is of interest to researchers for two reasons. The first is systemic: diet influences body weight, lipid metabolism, insulin resistance, and inflammatory markers, all of which are often associated with psoriasis. The second is local: dietary patterns can alter the microbiota and metabolites involved in immune regulation.

But even when discussing a "psoriasis diet," the lack of basic information often arises: what macronutrients do patients actually consume, and whether their diets differ from the average. The authors emphasize that such assessments have been virtually nonexistent in the UK.

A separate challenge is nutrient sources. The same amount of protein in a diet can come from a variety of foods: meat, fish, dairy, legumes, and nuts. These sources carry different "companions," including saturated fats, fiber, polyphenols, salt, and additives. Therefore, it's wise to analyze not only "how much protein" but also "where the protein comes from."

Finally, most observational studies do not prove causality. However, they can identify hypotheses that are then worth testing in randomized clinical trials: for example, whether a shift to plant-based diets actually alleviates symptoms in some patients.

Why is this important?

If certain dietary patterns are consistently associated with more severe psoriasis, this helps doctors and patients discuss specific risk factors rather than abstract "no-nos": for example, sugary drinks as a major source of free sugars or a predominance of meat protein. Such cues are especially valuable when they persist after accounting for factors such as age, smoking, and psychological stress.

Purpose of the study

1. To describe macronutrient intakes in people with psoriasis in the UK and compare them with dietary reference ranges and national nutrition survey data.
2. To examine whether psoriasis severity is associated with the proportion of nutrients obtained from different food groups (including free sugars from beverages, protein from meat, and protein from plant sources).

Materials and methods

Design: An online, cross-sectional study among adults with psoriasis in the UK as part of the APPLE study (NCT05448352). Diet was assessed using the Food Frequency Questionnaire, and severity was assessed using the self-assessed Simplified Psoriasis Index.

Of the 806 website visitors, 429 consented, and 366 began the survey; after excluding incomplete responses and inaccurate energy reporting, 257 participants were included in the analysis. The majority were women (83%), with a median age of 40 years and a median body mass index of 25 kg/m². Fifty-one percent were overweight or obese.

Associations between nutrient sources and psoriasis severity were analyzed by intake quartiles with consistent adjustment for confounding factors. The effect of body mass index (BMI) on the results (i.e., the extent to which obesity could explain the association) was assessed separately.

Results and interpretation

Compared with dietary reference intakes, participants reported a higher proportion of free sugars: a median of 11.2% of energy, compared to the UK recommendation of no more than 5%. A fiber deficiency was also noted: a median of 20.2 g per day, with a significant proportion of people in both the psoriasis group and the general population failing to achieve recommended levels.

The strongest association concerned beverages: participants with the highest quartile of free sugars from beverages were more likely to report high psoriasis severity than the group with the lowest intake (adjusted odds ratio 3.85; 95% confidence interval 1.507–9.831; P-trend = 0.04). However, adding body mass index attenuated this association, suggesting a partial role of obesity as a mediator or confounder.

For protein, the picture was divided by source. A higher proportion of protein from meat was associated with higher odds of high psoriasis severity (odds ratio, 2.47; 95% confidence interval, 0.984–6.196), while a higher proportion of plant protein was associated with lower odds of high severity (odds ratio, 0.36; 95% confidence interval, 0.140–0.915). Importantly, these models controlled for body mass index.

Discussion

The authors emphasize that this is an association, not a proven cause: the cross-sectional design does not allow us to say that diet worsens psoriasis (or, conversely, that more severe psoriasis changes eating habits).

Moreover, the results appear logical from a "food context" perspective: a higher proportion of plant-based protein sources typically indicates higher fiber and phytonutrients, while meat protein can come with a higher content of saturated fat, salt, and certain dietary patterns. The authors explicitly note that the proportions of nutrients from different sources can be surrogate markers for other components of these foods.

Practical significance

The practical conclusion for everyday life sounds cautious, but concrete: if a person with psoriasis has a diet high in sugary drinks and low in fiber, these are reasonable adjustments, even outside the context of psoriasis. For clinical practice, this suggests that a dietary shift toward plant-based sources may be beneficial for some patients.

The work sets priorities for research: which dietary interventions should be tested in randomized trials (for example, reducing free sugars in beverages or replacing some meat protein with plant-based protein), and which indicators should be considered to separate the effect of diet from the effect of weight loss.

Restrictions

The main limitation is the cross-sectional design: causal inferences cannot be made.

Second, self-reporting: frequency of food consumption and severity of psoriasis were measured by questionnaires, which inevitably introduces measurement error and possible bias.

Third, the sample composition: most participants were female and predominantly white-British; this may limit the generalizability of the results to other populations.

Conclusions

In 257 adults with psoriasis in the UK, two typical dietary 'problem areas' were identified: free sugars above reference levels (median 11.2% of energy) and low fibre (median 20.2 g/day).

A higher proportion of free sugars from beverages and a higher proportion of protein from meat were associated with higher psoriasis severity, whereas a higher proportion of plant protein was associated with lower severity; these associations require testing in randomized clinical trials.

Comments from the study authors

The authors formulate the conclusion as a hypothesis rather than a recommendation: “the potential benefits of plant-based diets for people with psoriasis remain an open question” and need to be tested in randomized trials.

It is specifically emphasized that “the proportions of nutrients from food sources can be surrogate markers for other components in these products,” meaning that not only the percentage of protein or sugar is important, but also the dietary pattern itself.

News source: 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. European Journal of Nutrition, published 02/19/2026. DOI: 10.1007/s00394-026-03914-y.