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Psoriasis research, in plain view

A filterable library of the peer-reviewed studies behind our articles: what diet, movement, stress, sleep, and comorbidities do to psoriasis. Each card summarises one study and links straight to its primary source.

These studies describe population-level patterns, not personal prescriptions. Triggers vary from person to person, so use this as a map of what may be worth testing on your own skin, not a set of rules.

Research question

Can following a Mediterranean diet reduce psoriasis severity?

from the MEDIPSO trial
2025 🇪🇸 Spain Randomized trial
38
people
16 wk
duration
vs.
control group
The strongest kind of study. People were randomly split into two groups, so it can point to cause, not just a link.
Research finding
A 16-week Mediterranean diet cut severity by about a third while the control group didn’t change, and it worked without weight loss.
% of the diet group reaching each clearance level
50% clearer
68%
75% clearer
47%
90% clearer
26%
Fully clear
11%
Read with careSmall, single-center, open-label: a strong design but early evidence. The 90%+ results rest on a handful of patients.
Researchers: J. Perez-Bootello, E. Berna-Rico, Á. Gonzalez-Cantero, et al. · JAMA Dermatology, 2025
Source ↗
Research question

Does more ultra-processed food go with more active psoriasis?

from the NutriNet-Santé cohort
2024 🇫🇷 France Cross-sectional
18,528
people
3
intake groups
France
nationwide
People were compared at a single moment in time, so this shows a link, not proof of cause.
Research finding
The heaviest ultra-processed-food eaters had about 36% higher odds of active psoriasis than the lightest. The link stayed after accounting for body weight.
odds of active psoriasis vs the lowest-intake group (1.0 = no difference)
Lowest intake
ref
Middle third
1.14×
Highest third
1.36×
Nonactive (quiet) psoriasis showed no such gradient.
Read with careA single snapshot cannot say which came first, and psoriasis was self-reported. When cases were limited to dermatologist-confirmed ones, the top-tier link was no longer statistically significant.
Researchers: L. Penso, M. Touvier, B. Srour, et al. · JAMA Dermatology, 2024
Source ↗
Research question

Is a lower-quality diet linked to more severe psoriasis?

from the APPLE study
2025 🇬🇧 UK Cross-sectional
257
people
147-item
diet survey
UK
nationwide
A single-snapshot comparison, so it shows links, not cause. Diet and severity were self-reported.
Research finding
People with the lowest-quality diets were 2 to 4 times more likely to report severe psoriasis. For most patterns the link ran through body weight. Only a DASH-style (heart-healthy) pattern held up on its own.
odds of severe psoriasis, poorest vs best adherence (1.0 = no difference)
DASH dietheld after weight
3.75×
Healthy plant-basedvia body weight
4.04×
Unhealthy plant-basedeating little of it
0.25×
Red and processed meat was the individual food most consistently tied to worse skin.
Read with careSmall sample (257), mostly white-British women, and a single snapshot, so it cannot show direction. Confidence ranges are wide. A 2025 correction to the study revised the Mediterranean-diet result to non-significant.
Researchers: S. Zanesco, T. Maruthappu, C. Griffiths, et al. · British Journal of Nutrition, 2025
Source ↗
Research question

Which diet changes did patients say improved their skin?

a National Psoriasis Foundation survey
2017 🇺🇸 USA Patient survey
1,206
people
25+
changes tested
USA
nationwide
People were asked what they’d tried and what helped: useful real-world experience, but not proof that a change works.
Research finding
Cutting alcohol, gluten and nightshades were reported to help most, but no single change worked for even half the people who tried it.
% who reported their skin improved after cutting each one
Alcohol
54%
Gluten
53%
Nightshades
52%
Junk food
50%
White flour
50%
Dairy
48%
High-fat foods
37%
Red meat
30%
Read with careSelf-reported and recalled, so this reflects patient experience, not proof that any change works. Effects are personal.
Researchers: L. Afifi, M. Danesh, K. Lee, et al. · Dermatology & Therapy, 2017
Source ↗
Research question

Does drinking alcohol raise your risk of psoriasis?

a dose-response meta-analysis of 11 observational studies
2026 🌍 Multi-country Meta-analysis
11
studies
370,966
people
43%
variation
All observational. People weren’t assigned to drink or not drink, so this shows a link, not proof that alcohol causes psoriasis.
Research finding
Drinkers had about 33% higher risk of developing psoriasis. But once the analysis corrected for studies likely missing from the record, that dropped to about 19%.
risk of developing psoriasis vs non-drinkers (1.0 = no difference)
Non-drinkers
ref
Drinkersas published
1.33×
Drinkerscorrected estimate
1.19×
Smoking, measured in the same review, carried a larger and more consistent risk (1.67×). Among people who already have psoriasis, three studies linked heavier drinking to developing psoriatic arthritis (2.80×), but those studies disagreed sharply with each other.
Read with careA statistical test flagged that studies finding no effect are probably missing from the published record. Drinking also travels with smoking, higher body weight and other factors, and not every study fully accounted for smoking, so the authors say the true figure is more likely to sit below the headline than above it.
Researchers: D. Chen, G. Ye, J. Yang, et al. · Frontiers in Public Health, 2026
Source ↗
Research question

Does losing weight make psoriasis treatment work better?

a Cochrane review of randomized trials
2019 🌍 Pooled Trials + review
6
diet trials
499
people
vs.
usual care
Pooled from randomized trials, the design that can point to cause. Cochrane rated the skin-clearance evidence low quality.
Research finding
Across randomized trials, calorie-controlled weight loss modestly improves psoriasis and helps treatment work better. In one trial, adding a weight-loss diet to a low drug dose roughly doubled the share reaching 75% clearance.
reached 75% clearer skin (PASI 75) in one randomized trial (n=61)
Diet + low dose
67%
Low dose alone
29%
Pooled across the diet trials, calorie restriction made PASI 75 about 1.66 times as likely as usual care.
Read with careAlmost all trials enrolled people carrying extra weight, so the effect in leaner people is unknown. Gains were modest (roughly 2 to 3 PASI points), and diet worked alongside treatment, not instead of it.
Researchers: P. Gisondi et al. (trial), Am J Clin Nutr, 2008 · S. Ko et al. (review), Cochrane, 2019
Source ↗
Research question

Does losing weight improve psoriasis?

a systematic review and meta-analysis of 13 randomized trials
2026 🌍 Multi-country Meta-analysis
13
RCTs
1,145
people
−6.7 kg
vs control
Pooled from randomized trials, the design that can point to cause. Eleven interventions changed diet (four added exercise), and three used weight-loss medication.
Research finding
People who lost weight saw severity fall by about 2.5 PASI points more than controls, were about 1.6× as likely to reach 75% clearer skin, and reported better quality of life.
change in PASI severity score vs control (line = no effect; left of it = improvement)
All trials14 comparisons
−2.5
Lower-bias trialsstricter check
−1.2
Dropping the trials at high risk of bias halved the effect, though it stayed significant. Reaching 75% clearer skin was more likely (RR 1.6, 1.1–2.2), but 50% and full clearance showed no significant difference. Quality of life improved by 5 points on the 30-point DLQI scale. The earlier Cochrane review (2019) pointed the same way with low-quality evidence; a 2026 network analysis of a similar trial pool found the skin effect uncertain.
Read with careResults varied widely between trials (I² = 85%), and funnel plots hinted that small positive studies may be over-represented. Trials enrolled people carrying extra weight (average BMI about 31), so the effect in leaner people is unknown. The authors frame weight loss as an add-on to treatment, not a replacement.
Researchers: S. Morrow, P. Hawkins, C.E.M. Griffiths, et al. · Journal of the European Academy of Dermatology and Venereology, 2026
Source ↗
Research question

Can losing weight through diet and exercise ease psoriasis?

a randomized controlled trial of 303 overweight patients
2014 🇮🇹 Italy RCT
303
patients
20
weeks
2
arms
A randomized trial, the strongest single design here. But exercise was combined with a weight-loss diet, so the effect of exercise on its own can’t be separated out.
Research finding
Both groups improved, but the diet-and-exercise group improved about twice as much: a median 48% drop in psoriasis severity versus 25.5% for advice alone.
median PASI reduction at 20 weeks (more is better)
Diet + exercise
48%
Advice only
25.5%
A PASI-50 response (at least a 50% improvement) was also more common with diet and exercise: 49.7% versus 34.2%. Everyone in the trial was already on systemic psoriasis medication.
Read with careBecause exercise came packaged with a weight-loss diet, the trial can’t tell you how much of the benefit was the exercise itself. Only about 30% of the intervention group actually hit the 5% weight-loss target, and all patients were overweight or obese, so results may not carry over to people at a healthy weight.
Researchers: L. Naldi, A. Conti, S. Cazzaniga, et al. · British Journal of Dermatology, 2014
Source ↗
Research question

Does exercise help even without dieting?

a randomized controlled trial of 118 men with mild psoriasis
2023 🇪🇸 Spain RCT
118
men
16
weeks
2
arms
A randomized trial in which both groups ate much the same, so the gains can be credited to the exercise itself rather than to weight loss or diet.
Research finding
A 16-week treadmill programme significantly improved fatigue, physical function and pain, while the control group did not change. It was safe, with no rise in muscle-damage markers.
improvement from baseline in the exercise group (the control group did not change)
Fatigue
14%
Physical function
20%
Pain
26%
Fitness, body-fat percentage and cholesterol also improved, and adherence was excellent at 92%.
Read with careThis trial measured how patients felt and functioned, not their skin severity, so it is not evidence that exercise clears plaques. It was also limited to young men aged 18 to 45 with mild psoriasis and no psoriatic arthritis, so the results may not carry over to everyone.
Researchers: A. J. Diaz, M. A. Rosety, J. C. Armario, et al. · Nutrients, 2023
Source ↗
Research question

Can a walking programme clear psoriasis?

a single-arm pilot study of 16 patients
2024 🇬🇧 UK Pilot
16
patients
20
weeks
1
arm
A small before-and-after pilot with no control group. Skin was measured objectively, but the improvement can’t be firmly separated from natural fluctuation, seasonal change, or the effect of taking part.
Research finding
Psoriasis severity fell significantly over the programme, and half the group reached a PASI-50 response, meaning skin at least 50% clearer, by week 20.
participants at least 50% clearer at week 20 (more is better)
PASI-50 reached
50%
Psoriasis severity was significantly lower than baseline at both week 10 (p = 0.01) and week 20 (p = 0.001). Cardiovascular fitness, psychological wellbeing and functional capacity also improved.
Read with careWith only 16 people and no comparison group, this is a pilot, not proof. A before-and-after change like this can be nudged by regression to the mean, the season, and the extra attention and motivation of joining a study, none of which a single-arm design can rule out. Participants were also motivated volunteers, so the result may not carry over to everyone.
Researchers: R. Sheppard, W. K. Gan, G. L. Onambele-Pearson, H. S. Young · Skin Health and Disease, 2024
Source ↗
Research question

Can exercise lower your risk of getting psoriasis?

a prospective cohort of 86,655 women (Nurses’ Health Study II)
2012 🇺🇸 United States Cohort
86,655
women
14 yr
follow-up
1,026
new cases
Prospective: activity was recorded years before any psoriasis appeared, so the timing runs the right way for cause. It’s still observational, not a trial.
Research finding
The most active women were about 28% less likely to develop psoriasis than the least active. The protection was strongest for vigorous exercise, and showed up only for running and aerobics, not walking.
risk of developing psoriasis vs the least-active women (1.0 = same risk)
Least active
ref
Most active overalltop activity quintile
0.72×
Vigorous exercisestrongest effect
0.66×
The benefit was specific to vigorous forms such as running and aerobic exercise or calisthenics. Walking, jogging, tennis, swimming and cycling showed no measurable link to risk.
Read with careActivity was self-reported through questionnaires, and the study followed only female nurses, so the exact numbers may not transfer to everyone. As an observational study it shows a strong association, not proof that exercise prevents psoriasis.
Researchers: H. C. Frankel, J. Han, T. Li, A. A. Qureshi · Archives of Dermatology, 2012
Source ↗
Research question

Can psychological stress bring on psoriasis?

a systematic review and meta-analysis of 39 studies
2018 🌍 Multi-country Meta-analysis
39
studies
32,537
patients
1
prospective
Mostly retrospective: patients recalled whether stress came before psoriasis. This shows a link, not proof that stress causes it.
Research finding
People who recalled stressful events before psoriasis onset had about 3.4× higher odds of the disease. But that rested on retrospective recall, and a documented stress-disorder diagnosis showed no difference.
odds of psoriasis after antecedent stress (1.0 = no difference)
No stress exposure
ref
Stressful events before onsetretrospective recall
3.4×
Documented stress disorderno difference
1.2×
Only one small prospective cohort existed; it found a modest link (r = 0.28). The review concluded there is no convincing evidence stress strongly causes psoriasis.
Read with careThe 3.4× figure comes from retrospective case-control studies with high inconsistency (I² = 87%). Recall bias is real: patients who believe stress triggered their psoriasis may remember stressful events more readily.
Researchers: I. Snast, O. Reiter, L. Atzmony, et al. · British Journal of Dermatology, 2018
Source ↗
Research question

Does treating the mind reduce psoriasis severity?

a systematic review and meta-analysis of 8 randomized trials
2019 🌍 Multi-country Meta-analysis
8
RCTs
765
people
5
CBT trials
Randomized trials, the strongest design for cause and effect. But they were open-label and varied widely, so weigh the modest effect size accordingly.
Research finding
Adding psychological therapy to usual care produced a small but real drop in skin severity (PASI). The benefit came almost entirely from CBT, and was strongest in person and in people with more severe psoriasis.
change in PASI severity score (line = no effect; left of it = improvement)
All psychological therapy
−1.36
CBT only5 trials
−1.80
Non-CBT therapynot significant
−0.70
PASI runs from 0 to 72, so a drop of about 1.4 points is small in absolute terms. The benefit was clearest for in-person CBT (−2.03) and moderate-to-severe disease (−1.95); remote delivery and mild disease showed little effect.
Read with careEight open-label trials with high inconsistency (I² = 79%). Psychotherapy cannot be blinded, so some benefit may reflect expectation, and non-CBT approaches and remote delivery did not show a clear effect. The absolute change is modest.
Researchers: Y. Xiao, X. Zhang, D. Luo, et al. · Psychology Research and Behavior Management, 2019
Source ↗
Research question

Does therapy help people with psoriasis feel better?

a systematic review and meta-analysis of 19 studies
2019 🌍 Pooled Meta-analysis
19
studies
≤664
per outcome
1
blinded
Controlled studies, the right design for testing whether something works. But reporting was poor, so the review rated most studies’ risk of bias as unclear.
Research finding
Therapy, mostly CBT or mindfulness, gave a small-to-medium lift in quality of life and eased anxiety. The effect on depression was not statistically clear.
effect of therapy vs comparison group (line = no effect; right of it = improvement)
Quality of life6 studies
0.28
Anxiety6 studies
0.36
Depressionnot significant
0.37
Standardized effect sizes: about 0.2 is small, 0.5 is medium. Depression’s estimate is similar in size, but its range crosses zero, so no effect can’t be ruled out. A 2025 network analysis of 13 studies pointed to CBT specifically for easing anxiety.
Read with careStudies reported their methods poorly and only one blinded patients, so expectation may account for some of the benefit. Each result rests on a few hundred people. This review measured how people felt, not their skin, so it is not evidence that therapy clears plaques.
Researchers: J.M. Zill, E. Christalle, N. Tillenburg, et al. · British Journal of Dermatology, 2019
Source ↗
Research question

How common is poor sleep in psoriasis?

a validated-measure survey of 186 people with psoriasis
2017 🇬🇧 UK Survey
186
people
76%
poor sleep
33%
probable apnea
A self-selected online survey measured at one point in time. It shows how widespread poor sleep is in this group, not that psoriasis is the cause.
Research finding
About 76% scored as poor sleepers on a validated scale, and roughly a third screened positive for probable sleep apnea. The strongest predictors of bad sleep were a racing mind at bedtime, itch, and low mood.
what most predicted poor sleep (relative strength)
Racing mind at bedtime
0.26
Itch
0.26
Low mood
0.24
Body tension
0.17
Standardized weights from the study. Together these explained about 43% of the differences in sleep quality between people.
Read with careThis was a one-time online survey of 186 volunteers who reported their own psoriasis diagnosis, so the group may lean toward people already struggling with sleep. It captures how common poor sleep is, not whether psoriasis causes it.
Researchers: A.L. Henry, S.D. Kyle, A. Chisholm, C.E.M. Griffiths, C. Bundy · British Journal of Dermatology, 2017
Source ↗
Research question

Is psoriasis linked to sleep apnea?

a systematic review and meta-analysis of 7 studies
2020 🌍 Multi-country Meta-analysis
7
studies
5.8M
subjects
3
prospective
Pooled from case-control, cross-sectional and cohort studies. The cohorts followed people over time, strengthening the link — but it’s still observational, not proof of cause.
Research finding
Psoriasis and sleep apnea raise each other’s odds. People with psoriasis had about 2.6× higher odds of sleep apnea, and people with sleep apnea had about 2.5× higher risk of later psoriasis.
how much each condition raises the odds of the other (1.0 = no difference)
No association
ref
Sleep apnea in psoriasiscase-control + cross-sectional
2.60×
Psoriasis in sleep apneaprospective cohorts
2.52×
The two directions used different measures — an odds ratio one way, an incidence rate ratio the other — but both point the same way, and the cohort side had no heterogeneity (I² = 0%).
Read with careOnly seven studies, and the sleep-apnea-in-psoriasis estimate rests on four case-control and cross-sectional studies with a wide confidence range (1.07–6.32). Shared drivers such as obesity, which raises the risk of both, weren’t fully separated out.
Researchers: T.-Y. Ger, Y. Fu, C.-C. Chi · Scientific Reports, 2020
Source ↗
Research question

How many people with psoriasis develop psoriatic arthritis?

a proportion meta-analysis of 266 studies
2019 🌍 Multi-country Meta-analysis
266
studies
976,408
patients
19.7%
pooled
A pooled prevalence, not a personal risk. Estimates varied widely between studies, so read this as a population average rather than your own odds.
Research finding
Across 266 studies, about 1 in 5 people with psoriasis also had psoriatic arthritis — a pooled 19.7%. Older sources often cite “up to 30%,” but the meta-analytic figure is lower.
share of psoriasis patients who also have psoriatic arthritis (bars scaled to a 25% axis)
All patients
19.7%
Europe
22.7%
N. America
19.5%
Asia
14.0%
Prevalence was higher (23.8%) in studies using the formal CASPAR classification criteria, and lower in children (3.3%).
Read with careBetween-study heterogeneity was very high, so the single pooled number hides a lot of variation. Whether an individual develops psoriatic arthritis depends on factors this average cannot predict — which is exactly why watching your own joints over time matters more than the headline percentage.
Researchers: F. Alinaghi, M. Calov, L.E. Kristensen, et al. · Journal of the American Academy of Dermatology, 2019
Source ↗
Research question

Does psoriasis raise the risk of heart attack and stroke?

a systematic review and meta-analysis of 9 observational studies
2013 🌍 Multi-country Meta-analysis
9
studies
201,239
mild psoriasis
17,415
severe psoriasis
All nine studies were observational. Risk was adjusted for some standard heart-disease factors, but this shows association, not proof that psoriasis itself causes the events.
Research finding
Risk rose with disease severity. People with severe psoriasis had about 1.7× the risk of heart attack and 1.6× the risk of stroke. In mild psoriasis the increase was smaller but still present.
risk of a cardiovascular event vs the general population (1.0 = no difference)
General population
ref
Heart attacksevere psoriasis
1.70×
Strokesevere psoriasis
1.56×
Heart attackmild psoriasis
1.29×
Severe psoriasis was also linked to higher cardiovascular mortality (1.39, 1.11–1.74). The pattern — bigger risk with more severe disease — is part of why researchers suspect inflammation itself plays a role.
Read with careSeverity was defined differently across studies, and adjustment for smoking, weight and blood pressure varied, so some residual confounding is likely. A larger 2022 cohort meta-analysis (31 studies) found the same direction with slightly smaller effects.
Researchers: E.J. Armstrong, C.T. Harskamp, A.W. Armstrong · Journal of the American Heart Association, 2013
Source ↗
Research question

Is psoriasis linked to fatty liver disease?

a systematic review and meta-analysis of 7 case-control studies
2015 🌍 Multi-country Meta-analysis
7
studies
267,761
patients
0
prospective
All case-control studies, mostly low to moderate quality. This shows psoriasis and fatty liver tend to occur together, not that one causes the other.
Research finding
People with psoriasis had about 2.2× the odds of non-alcoholic fatty liver disease, and the odds climbed with more severe skin disease and with psoriatic arthritis.
odds of fatty liver disease (1.0 = no difference)
No psoriasis
ref
Any psoriasis
2.15×
Mod–severevs mild psoriasis
2.07×
With arthritispsoriatic arthritis
2.25×
Newer and larger meta-analyses land a little lower (around 1.7–2.2), but all point the same way: fatty liver is roughly twice as common in psoriasis.
Read with careOnly seven studies, all case-control and of low-to-moderate quality, with meaningful heterogeneity. Obesity and metabolic syndrome drive both conditions and were not fully separated out.
Researchers: R. Candia, A. Ruiz, R. Torres-Robles, et al. · Journal of the European Academy of Dermatology and Venereology, 2015
Source ↗
Research question

Are people with psoriasis more likely to be depressed?

a systematic review and meta-analysis of 98 studies
2014 🌍 Multi-country Meta-analysis
98
studies
28%
had symptoms
12%
clinical depression
Most of the 98 studies had no control group. The odds ratio below comes from the subset with proper population-based comparison, which is the most reliable slice.
Research finding
In population-based studies, people with psoriasis were about 1.5× as likely to have clinical depression. Roughly 1 in 4 reported depressive symptoms on questionnaires.
odds of clinical depression vs the general population (1.0 = no difference)
General population
ref
Psoriasispopulation-based
1.57×
The 1.57 figure is the trustworthy one, drawn from studies with proper comparison groups. Systemic inflammation may play a direct role, not just the strain of living with a visible condition.
Read with careMost of the 98 studies came from specialist clinics without a control group, which can overstate how common depression looks. The odds ratio is drawn from the smaller, more reliable set of population-based studies.
Researchers: E.A. Dowlatshahi, M. Wakkee, L.R. Arends, T. Nijsten · Journal of Investigative Dermatology, 2014
Source ↗

“Nearly 125 million people worldwide have psoriasis, you’re not alone on this journey.”

Itchi is a wellbeing tool, not a medical provider. The summaries here are simplified for readability and are educational only. They are not a substitute for professional medical advice, diagnosis, or treatment. Do not start, stop, or change any medication based on what you read here. Each card links to its original paper, and copyright in those papers stays with their authors and publishers.