Name: Psoriasis: Diet and Lifestyle Modulate It and Improve Drug Response, But Do Not Cure It
Creator: Realised
Published: 2026-06-01

Summary

Psoriasis is a systemic immune-mediated disease running on the IL-23/IL-17 axis, and the honest read is two-sided at once: lifestyle genuinely modulates it — losing excess weight is the single strongest and most guideline-endorsed lever, it lowers severity AND improves how well biologics work, while stopping smoking and moderating alcohol help and a Mediterranean pattern plus omega-3 give modest, inconsistent benefit — AND it is not curable by diet, supplements, or "gut healing," because moderate-to-severe disease is transformed only by systemic therapy where IL-23 inhibitors clear three-quart

Why Moderate

Moderate Evidence because the entry's center of gravity — the actionable lifestyle claims — rests on observational cohorts plus a small number of RCTs and meta-analyses with modest effect sizes, not on the large biologic RCTs. The lifestyle thesis is genuinely Moderate, and the entry is honest about that.

NOT Strong for the headline because while individual anchors are Strong (the weight-loss guideline recommendation, the smoking dose-response, the biologic efficacy), the load-bearing actionable claim — that lifestyle modulation is worth doing — sums to a set of modest, partly observational effects, and the diet/omega-3/vitamin D levers are mixed-to-null.

NOT Emerging because the spine is well-evidenced: weight-loss benefit, smoking dose-response, NPF guideline positions, biologic efficacy, and the comorbidity load are all solidly supported. Only the specific diet and supplement levers sit lower, and the entry marks them rather than inheriting their uncertainty.

The per-lever split (read this, not just the headline):
• Weight loss (severity + drug response): Strong-to-Moderate — the only strong NPF dietary recommendation, plus consistent BMI-response signal and a meta-analytic effect.
• Smoking cessation: Moderate — large cohorts with a graded dose-response, but observational.
• Alcohol moderation: Moderate — real association, mixed across populations.
• Mediterranean diet / omega-3: Emerging-to-Moderate — modest, inconsistent, partly observational.
• Oral vitamin D: Moderate-to-Emerging — mostly null in RCT meta-analysis; correct deficiency for general health only.
• Biologic efficacy: Strong (phase 3 RCTs) — the counterweight, not the lifestyle thesis; cardiovascular benefit is Moderate observational.
• Comorbidity load: Moderate — well-replicated epidemiologic association.

Practical takeaway

The framing to hold: do the lifestyle work because it genuinely modulates the disease and improves drug response, but treat it as adjunctive support toward baseline, never as a cure. The dividing line that matters most is severity: mild disease may be controlled with topical therapy plus lifestyle, but moderate-to-severe disease needs systemic therapy, and lifestyle is the adjunct, not the alternative.

The strongest, least-conflicted lever first.
• Lose excess weight if overweight or obese. This is the single strongest and most guideline-endorsed dietary lever, and it is the least commercially contaminated one. It lowers severity directly and improves how well biologics work. Use a sustainable hypocaloric approach; weight-loss mechanics are owned by energy_balance_governs_weight. Aim matters — larger benefit appears at 10-15% body-weight loss — but any sustained loss in an overweight patient is worth having.

Remove the aggravators.
• Stop smoking. The dose-response association is clear, and cessation is a legitimate lever as well as a major win for the cardiovascular comorbidity that shadows psoriasis.
• Moderate alcohol. The association is real if less certain in magnitude than smoking. Moderation is reasonable and, again, helps the comorbidity picture.

The modest, low-risk additions (try, don't rely on).
• Eat a Mediterranean pattern. Modest, inconsistent benefit, but low-cost, low-risk, and good for the cardiometabolic comorbidities regardless of its skin effect.
• Omega-3 is a reasonable low-risk adjunct with mixed evidence for severity; treat it as optional, not as treatment (detail in omega3_repletion).
• Correct frank vitamin D deficiency for general health if you are actually deficient — but do NOT expect oral vitamin D to clear psoriasis; the trial evidence is null. (Topical vitamin D analogues prescribed by a clinician are a different thing entirely.)

Manage stress as a flare trigger. Stress is a recognised trigger for flares; stress management is a sensible adjunct, framed as reducing flare likelihood, not as a cure.

What NOT to do — the load-bearing guardrail.
• Do not defer or decline systemic therapy for moderate-to-severe disease in favour of diet, supplements, or a gut-healing protocol. Biologics clear three-quarters of moderate-to-severe patients and are associated with lower cardiovascular risk. This is the genuine harm the entry exists to prevent.
• Do not present diet, "gut healing," or any supplement as a cure. None of them are.

Evidence detail

Why This Entry Exists

Psoriasis sits at the exact fault line this platform is built to hold: a real disease with real lifestyle levers, wrapped in a market that monetises the promise of a natural cure that does not exist. The instinct, when a chronic skin condition flares, is to look for the food or the gut-protocol that caused it and the diet that will clear it. Some of that instinct is right — lifestyle genuinely modulates psoriasis, and the modulation is not trivial. Losing excess weight does not just lower severity directly; it improves the response to the drugs that actually clear the disease. That is a strong, guideline-endorsed finding and it deserves to be stated plainly.

But the same instinct, taken to its conclusion, becomes the thing the evidence flatly contradicts: that diet or "gut healing" can cure psoriasis. It cannot. This is a systemic immune-mediated disease driven by a specific cytokine axis, and the interventions that transform moderate-to-severe disease are biologics, not elimination diets. The entry exists to hold both truths without letting either swallow the other — to credit the genuine lifestyle levers at their true, modest size while naming the ceiling honestly, because the cost of getting this wrong is not a wasted supplement. It is a patient with a comorbidity-laden systemic disease deferring the only treatment that clears them.

What bad advice this protects against, in all directions:
• "You can cure psoriasis through diet / by healing your gut" → false. No diet, supplement, or gut-protocol cures psoriasis. The gut-dysbiosis link is biologically plausible and emerging, not actionable or curative.
• "Lifestyle does nothing, just take the drug" → also wrong. Weight loss lowers severity and improves biologic response; smoking and alcohol worsen the disease; the Mediterranean pattern and omega-3 give modest benefit. Lifestyle is genuine adjunctive support.
• "Vitamin D fixes psoriasis" → oral vitamin D does NOT reliably reduce severity in trials. (This is the ORAL/systemic supplement; topical vitamin D analogues like calcipotriol are a separate, effective standard therapy and out of scope.)
• "Fish oil / Mediterranean diet clears it" → these give modest, inconsistent benefit at best. Low-cost and low-risk, worth trying, never relied upon as treatment.
• "It's just a skin condition" → false in the dangerous direction. Psoriasis carries serious systemic comorbidity load — psoriatic arthritis and elevated cardiometabolic/cardiovascular risk — which is exactly why under-treating it matters.
• "Biologics are dangerous, avoid them" → the IL-23 inhibitors clear ~75% of moderate-to-severe patients and are associated with LOWER cardiovascular event rates than older oral therapies. For moderate-to-severe disease they are transformative.

This entry owns the diet-and-lifestyle consensus gaps of psoriasis. It defers general skincare to evidence_based_minimal_skincare, weight-loss mechanics to energy_balance_governs_weight, vitamin D dosing to vitamin_d3_high_dose_supplementation, omega-3 detail to omega3_repletion, and cardiovascular comorbidity management to cardiovascular_health_management. It does NOT re-argue acne or eczema. It states those boundaries and routes there rather than re-explaining them.

Evidence

Organised by lever, with the tier signal inline. The headline is Moderate, but the levers split sharply — read the tiers, not just the thesis. The Strong-evidence biologic findings are the counterweight that bounds the lifestyle thesis, not the thesis itself.

Weight loss — the strongest, least-conflicted lever, and it improves drug response (Strong-to-Moderate Evidence).

1. The only STRONG dietary recommendation in the National Psoriasis Foundation guideline is hypocaloric weight reduction in overweight/obese patients. The 2018 NPF medical-board systematic review gave its single strong recommendation to weight-reduction/hypocaloric dieting for overweight or obese psoriasis patients, and simultaneously found limited-to-no evidence for dietary supplements including fish oil and vitamin D. This is the most authoritative anchor in the entry: it endorses weight loss and deflates the supplement market in the same document. (Ford AR, Siegel M, Bagel J, et al. "Dietary Recommendations for Adults With Psoriasis or Psoriatic Arthritis From the Medical Board of the National Psoriasis Foundation: A Systematic Review." JAMA Dermatology 2018. Strong Evidence — guideline from a systematic review by a national medical board, cited only for what it covers. NPF takes pharmaceutical funding, which if anything biases toward drugs — yet it still endorsed weight loss and was skeptical of supplements, a cui-bono cut that strengthens rather than undermines the finding.)

2. Obesity worsens severity AND blunts biologic response — so weight loss works on two channels at once. Higher BMI correlates with worse PASI and with diminished, shorter-lasting biologic response, driven partly by subtherapeutic serum drug levels at fixed doses and partly by adipokine-driven inflammation (leptin, TNF-alpha and IL-6 up, adiponectin down, feeding the Th17 axis). This is the load-bearing "lifestyle improves drug response" receipt. (Correlation between BMI and PASI under biologic therapy, Naldi L et al. (PubMed 20136916), plus adipokine/Th17 mechanism reviews; METABOLyx (secukinumab with/without lifestyle, n=768, NCT03440736) is the dedicated RCT testing the combination. Moderate Evidence — consistent observational/cohort signal plus a large ongoing RCT, with a biologically coherent mechanism. METABOLyx is Novartis-sponsored (secukinumab's maker); a pharma-run trial showing lifestyle ADDS to its own drug is mild evidence against pure marketing bias, but read effect sizes from independent meta-analyses, not the sponsor.)

3. Weight-loss interventions produce real but MODEST PASI improvement. Pooled/meta-analytic average PASI reduction is roughly 2.5 points in overweight patients, with larger gains at 10-15% body-weight loss, and a prospective follow-up of an RCT cohort showed the severity benefit was durable. The honest magnitude is a meaningful adjunct, not a cure. (Systematic review and meta-analysis of weight-loss interventions on psoriasis severity, BJD 2025 (PubMed 41416383); long-term weight-reduction follow-up of an RCT cohort, Am J Clin Nutr (ScienceDirect S0002916522045373). Strong-to-Moderate — systematic review/meta-analysis of mostly small trials with modest effect sizes, academic/dietetic with low commercial conflict; the effect is honestly modest and reported as such.)

Smoking and alcohol — cessation is a legitimate lever, with a clear dose-response for smoking (Moderate Evidence).

4. Smoking shows a graded dose-response association with incident psoriasis. Versus never-smokers, current smokers carried RR ~1.94 (95% CI 1.64-2.28) and past smokers ~1.39, rising with pack-years, pooled across roughly 185,836 participants from the Nurses' Health Study I/II and the Health Professionals Follow-up Study. The graded dose-response strengthens the causal inference. (Li W, Han J, Choi HK, Qureshi AA. "Smoking and Risk of Incident Psoriasis Among Women and Men in the United States: A Combined Analysis." Am J Epidemiol 2012, pooling the Nurses' Health Study I/II and the Health Professionals Follow-up Study. Moderate Evidence — large prospective cohorts with dose-response, but observational. NIH/academic cohorts, minimal commercial conflict.)

5. Alcohol is associated with risk, but the signal is mixed across populations. In US women (Nurses' Health Study II), intake at ≥2.3 drinks/week carried RR 1.73 (95% CI 1.16-2.58) for incident psoriasis. But a Taiwanese cohort found no association, so the magnitude is genuinely less certain than for smoking. Moderation is reasonable; do not over-state the size. (Qureshi AA et al., alcohol intake and incident psoriasis in US women (PMC3017376); contrast: Taiwanese cohort, JAAD (PubMed 30528570). Moderate Evidence — observational and heterogeneous across populations; the mixed finding is reported honestly rather than cherry-picked. Academic cohorts, minimal commercial conflict.)

Diet pattern, omega-3, and vitamin D — modest, inconsistent, or null (Moderate-to-Emerging).

6. Oral vitamin D supplementation does NOT reliably reduce psoriasis severity. A meta-analysis of RCTs found no significant PASI effect (non-significant after Hartung-Knapp adjustment), and a 2023 randomized double-blind placebo-controlled trial in patients with lower-range 25(OH)D found no PASI difference versus placebo. Correcting frank deficiency is reasonable for general health, but "fix your vitamin D to clear psoriasis" is not supported. This null verdict is about reducing the SEVERITY of existing psoriasis in standard-dose oral RCTs (no PASI benefit), which is a different question from incident-disease PREVENTION (the VITAL autoimmune-incidence signal) or uncontrolled mega-dose protocols (Coimbra), so it does not conflict with vitamin_d3_high_dose_supplementation. Note: this is ORAL systemic vitamin D — topical vitamin D analogues (calcipotriol) are a separate, effective standard therapy and out of scope. (Theodoridis X et al., "Effectiveness of oral vitamin D supplementation in psoriasis severity: a systematic review and meta-analysis of RCTs," Nutrition 2021;82:111024 (PubMed 33183899); vitamin D RCT in lower-range 25(OH)D (PMC10061314, 2023). Moderate-to-Emerging — meta-analysis of small heterogeneous RCTs, mostly null with inconsistent direction. Academic nutrition groups; the null runs against the supplement industry's interest, so low pro-supplement bias. Dosing detail deferred to vitamin_d3_high_dose_supplementation.)

7. Mediterranean-pattern diet and omega-3 give modest, inconsistent benefit. The signal is genuinely mixed: one systematic review found an omega-3 PASI improvement, an older 12-study review called fish oil inconclusive, and Mediterranean-adherence associations with lower severity are observational. None of this supports diet as treatment; it supports diet as a low-cost, low-risk adjunct worth trying but not relied upon. (Systematic and narrative reviews of omega-3/fish oil and Mediterranean-pattern diet in psoriasis; see omega3_repletion for the supplement-side detail. Emerging-to-Moderate — heterogeneous, partly observational, with effect sizes too inconsistent to call established.)

Biologics — the counterweight that bounds the whole entry (Strong Evidence for efficacy).

8. IL-23 inhibitors clear three-quarters of moderate-to-severe patients — the "natural cure" market overshoots this. Risankizumab achieved PASI 90 in ~75% of patients at week 16 (UltIMMa-1: 75.3%, UltIMMa-2: 74.8%) versus ~2-5% on placebo and ~42-48% for ustekinumab. Biologic treatment is also associated with LOWER 5-year cardiovascular event incidence (~10.68% versus ~16.17% on oral anti-psoriatics). This is why deferring effective treatment in favour of "gut healing" is a real harm, not just an efficacy gap. (Gordon KB et al., UltIMMa-1 and UltIMMa-2 risankizumab phase 3 trials, Lancet 2018 (PubMed 30097359); population-based cohort on biologics and cardiovascular risk, PLOS Medicine 2025 (journal.pmed.1004591). Strong Evidence for efficacy — large double-blind active- and placebo-controlled phase 3 RCTs; the cardiovascular finding is Moderate observational-cohort evidence. UltIMMa is AbbVie/Boehringer-sponsored (risankizumab's makers), a strong conflict — but PASI 90 ~75% is corroborated across independent IL-23 agents (guselkumab) and real-world registries, so the magnitude survives the sponsorship discount. Used as the counterweight, not the lifestyle thesis.)

9. Psoriasis carries serious systemic comorbidity load. Psoriatic arthritis develops in a substantial minority, and the disease carries elevated cardiometabolic and cardiovascular risk. This comorbidity burden is what converts under-treatment from an efficacy question into a harm question, and it justifies the entry's firm stance against the "natural cure" frame. (Impact of biologics on comorbidities in psoriasis/PsA, Biomedicines/MDPI 2025 (13/9/2219); emulated target-trial of MACE/VTE across biologic classes, JAAD 2025 (PubMed 39736358). Moderate Evidence — consistent epidemiologic association plus cohort/target-trial-emulation evidence; the comorbidity-risk direction is well-replicated independent of funding source. Cardiovascular comorbidity management deferred to cardiovascular_health_management.)

Mechanism

Why this is a systemic disease, not a skin problem. Psoriasis is driven by a self-reinforcing immune loop on the IL-23/IL-17 axis: dendritic cells release IL-23, which drives Th17 cells to produce IL-17, which in turn drives keratinocytes to hyperproliferate and to amplify the inflammatory signal that feeds the loop. The plaques are the visible end of a systemic inflammatory process, which is why the disease tracks with arthritis and cardiometabolic risk and why the treatments that actually clear it are antibodies that interrupt this specific cytokine axis. Nothing in a diet directly switches off IL-23 or IL-17 signalling, which is the mechanistic reason diet cannot cure the disease.

Why weight loss works on two channels. Adipose tissue is not inert; it is an endocrine organ that secretes pro-inflammatory adipokines. In obesity, leptin, TNF-alpha and IL-6 rise while anti-inflammatory adiponectin falls, and this milieu feeds the same Th17 inflammation that drives psoriasis — so excess fat adds inflammatory fuel to the fire. That is the first channel: less adipose inflammation, lower severity. The second is pharmacokinetic. Many biologics are dosed at a fixed amount regardless of body size, so a larger body dilutes the drug to a lower effective serum concentration; reducing body mass raises the effective dose without changing the prescription. Weight loss therefore both lowers the baseline inflammatory load and makes a fixed-dose drug work harder, which is the mechanistic basis for the "lifestyle improves drug response" finding.

Why smoking and alcohol aggravate it. Smoking generates oxidative stress and shifts immune signalling in ways that promote the Th17/IL-17 pathway, consistent with the graded dose-response seen in the cohorts. Alcohol contributes inflammatory and possibly immune-modulating effects and may worsen disease and treatment adherence, though the population heterogeneity in the data means the mechanism is less cleanly established than for smoking.

Why "gut healing" overshoots. There is a real, emerging signal that the gut microbiome differs in psoriasis and that gut inflammation and systemic immune activation are linked. That is biologically plausible and worth watching. But "differs in" is not "is caused by and can be cured by," and the leap from an emerging association to a "leaky gut protocol cures psoriasis" claim is exactly the overshoot this entry exists to mark (see leaky_gut_intestinal_permeability). The dysbiosis link is a research direction, not an actionable lever.

Risks And Contraindications

• Harm of omission is the central hazard. The biggest real-world risk is a moderate-to-severe patient reading "lifestyle modulates psoriasis" and concluding they can manage it with diet and skip biologics. They cannot. The entry must always pair the lifestyle credit with the severity rule: mild disease may respond to topical-plus-lifestyle; moderate-to-severe needs systemic therapy, and lifestyle is ADJUNCTIVE.
• The vitamin D distinction is easy to get wrong. ORAL/systemic vitamin D supplementation does not reliably reduce psoriasis severity. TOPICAL vitamin D analogues (calcipotriol) are an effective, standard prescribed therapy. Conflating the two makes the entry look wrong to a dermatologist. Keep them distinct.
• Diet over-claim. Omega-3 and Mediterranean-diet evidence is genuinely mixed. Never present these as established or curative; frame as modest, low-cost, low-risk, worth trying but not relied upon.
• Gut-dysbiosis over-reach. The gut link is emerging/early-tier and must not be sold as actionable or curative. "Heal your gut to cure psoriasis" is precisely the overshoot the entry pushes back on.
• Comorbidity surveillance. Because psoriasis carries elevated psoriatic-arthritis and cardiometabolic/cardiovascular risk, lifestyle advice should be framed partly as comorbidity risk reduction, and worsening joint pain, swelling or stiffness warrants assessment for psoriatic arthritis.
• When to see a doctor. New or worsening joint pain or swelling (possible psoriatic arthritis), rapidly spreading or pustular/erythrodermic disease, or any moderate-to-severe disease that is not controlled by topicals warrants specialist (dermatology) assessment for systemic therapy. Lifestyle is not a substitute for that assessment.

Controversy

Nature: a real systemic immune-mediated disease with genuine lifestyle levers (weight loss strongly, smoking/alcohol/diet modestly) entangled with two opposing distortions — a "natural cure" market that overshoots a serious disease, and a drug-only frame that under-credits the real adjunctive levers. The error is at both poles.

Position A — "Lifestyle genuinely modulates psoriasis and is worth doing." The grounded, mechanism-specific take.
• Best evidence: weight loss is the strongest lever (the only strong NPF dietary recommendation), lowering severity ~2.5 PASI points on average and improving biologic response; smoking shows a graded dose-response (current-smoker RR ~1.94); alcohol is associated with risk in women (RR 1.73); Mediterranean pattern and omega-3 give modest benefit; the gut link is emerging.
• Where it goes wrong if overstated: it tips into "you can cure it / diet is the treatment" if you forget that every one of these is adjunctive and modest, and that the gut link is not yet actionable.

Position B — "Psoriasis is not curable by diet; biologics are what work." The systemic-disease take.
• Best evidence: the same NPF review found limited-to-no evidence for fish oil and vitamin D supplements; oral vitamin D meta-analysis is null; biologics (risankizumab PASI 90 ~75%) are transformative for moderate-to-severe disease and even associated with lower cardiovascular risk; the disease carries serious comorbidity load.
• Where it goes wrong if overstated: it can slide into "lifestyle does nothing, just medicate," dismissing the real weight-loss-improves-drug-response finding and the genuine smoking/alcohol/diet levers.

The funding/bias dimension — cui bono, both ways. Toward the drug-only frame: pharma funds the transformative-efficacy trials (UltIMMa = AbbVie/Boehringer; METABOLyx = Novartis) and benefits from a medication-centric story — though the efficacy magnitudes replicate across independent IL-23 agents and registries, so the discount is small. Toward the natural-cure frame: the "functional medicine," supplement and elimination-diet market monetises fish oil, vitamin D, and "leaky gut" protocols, selling the promise of a diet cure for an incurable systemic disease. Notably the most authoritative finding — the NPF guideline endorsing weight loss while skeptical of supplements — cuts against the supplement market despite NPF taking pharma money, and the null vitamin D meta-analyses come from academic groups with no supplement incentive.

Realised Position: Both positions are true at once, and the entry holds them together. Do the lifestyle work — lose excess weight (the strongest, most guideline-endorsed, least-conflicted lever), stop smoking, moderate alcohol, eat a Mediterranean pattern, manage stress as a flare trigger, and correct frank vitamin D deficiency for general health — because it genuinely modulates the disease and improves drug response. But name the ceiling honestly: this is recovery-toward-baseline and adjunctive support, NOT a cure. Mild disease may be controlled with topicals plus lifestyle; moderate-to-severe disease needs systemic therapy, and biologics are transformative and even cardioprotective. The "heal it naturally / gut-healing cure" market overshoots a real systemic disease with serious comorbidities, and deferring effective treatment for it is a genuine harm. Frame omega-3, Mediterranean diet, and the gut-dysbiosis link as modest or emerging, never as established or curative. The cleanest tell of an honest lever here is weight loss — the one with the best evidence and the least to sell.

Cross-Pillar Connections

This is a genuinely cross-pillar topic — the levers span diet, physical activity, behaviour change, and mental stress, and the harm sits in cardiometabolic comorbidity.
• Supplements (vitamin_d3_high_dose_supplementation): owns vitamin D dosing; this entry holds only the finding that oral vitamin D does not reliably reduce psoriasis severity and that deficiency-correction is for general health.
• Supplements (omega3_repletion): owns omega-3 repletion detail; this entry holds only the modest, inconsistent psoriasis-severity signal.
• Cross-pillar (cardiovascular_health_management): owns the cardiometabolic comorbidity management that psoriasis elevates and that weight loss, smoking cessation and a Mediterranean pattern all serve.
• Skin (evidence_based_minimal_skincare): owns general skincare; this entry defers all non-psoriasis-specific topical/skincare guidance there.
• Diet (energy_balance_governs_weight): owns weight-loss mechanics; this entry holds only that weight loss is the strongest psoriasis lever and improves biologic response.
• Gut (leaky_gut_intestinal_permeability): the "gut healing cures psoriasis" overshoot this entry marks; the gut-dysbiosis link is emerging, not actionable or curative.

What would change our mind

Falsifiability: explicit upgrade/downgrade criteria from source

• We'd upgrade the diet claims from modest to strong if a large, well-powered RCT showed a specific diet (Mediterranean, elimination, or a defined "gut" protocol) clears or substantially reduces psoriasis independent of weight loss, with replication — and that would force a title rethink.
• We'd move oral vitamin D or omega-3 from "mixed/null" to a genuine lever if a high-quality RCT showed a defined dose meaningfully lowers PASI versus placebo with replication.
• We'd weaken the strongest finding if the weight-loss-improves-biologic-response signal proved confounded (reverse causation, or if it vanished under weight-based dosing).
• We'd soften the "lifestyle improves drug response" framing to "improves baseline severity and comorbidity risk only" if METABOLyx reports that adding lifestyle to secukinumab produces no incremental PASI benefit.
• What would NOT move us: the core dual thesis is robust. Weight loss helps and is guideline-endorsed; biologics are transformative for moderate-to-severe disease; psoriasis is not curable by diet. Nothing realistic overturns that. Across all of it, independent (non-seller) funding is the decisive variable in how much weight a claim earns.

Industry bias note

Structural incentives the evidence base may reflect

Cui bono runs both ways here, and the entry says so.
• Toward the drug-only frame. The biologic industry funds the transformative-efficacy trials (UltIMMa = AbbVie/Boehringer, risankizumab's makers; METABOLyx = Novartis, secukinumab's maker) and benefits from a medication-centric story that under-credits lifestyle. But the efficacy magnitudes (PASI 90 ~75%) replicate across independent IL-23 agents (guselkumab) and real-world registries, so the sponsorship discount is small — the drugs really are that effective.
• Toward the natural-cure frame. The "functional medicine," supplement and elimination-diet market profits from the opposite story — that you can cure psoriasis through diet and gut healing — monetising fish oil, vitamin D, elimination diets, and "leaky gut" protocols. This is the market the entry is built to push back on, because it sells a cure for an incurable systemic disease and risks steering moderate-to-severe patients away from effective treatment.
• The clean signal. The most authoritative finding — the 2018 NPF guideline endorsing weight loss while skeptical of supplements — cuts against the supplement market despite NPF taking pharma money, and the null vitamin D meta-analyses come from academic groups with no supplement incentive. The weight-loss lever is the least conflicted and best-supported claim in the entry.
• The honest synthesis. Follow the least-conflicted evidence: weight loss (cheap, guideline-endorsed, no seller behind it) over both the bullish supplement claims and the dismissive drug-only framing.

Psoriasis: Diet and Lifestyle Modulate It and Improve Drug Response, But Do Not Cure It