- This article focuses on plaque psoriasis. The UK's specialist dermatology society says adults with plaque psoriasis who meet the criteria can be offered any currently licensed biologic, with the choice made using a decision aid (BAD biologic guideline, 2020 rapid update).
- The same guideline's psoriatic arthritis advice could not be re-checked in the fact-check pass, so it is not summarised here.
- Fish oil does not reliably help. A 2019 meta-analysis of 3 usable trials (337 people) found a pooled PASI change of −0.28 (95% CI −1.74 to 1.19), which is not significant (BMC Complementary and Alternative Medicine 2019).
- Oral vitamin D shows no clear benefit in the trials we could open. A 2023 meta-analysis of 4 RCTs (333 people) gave a PASI difference of −0.32 (95% CI −1.17 to 0.53) (PLoS One 2023).
- Curcumin looks promising but is unproven. A 2022 review pooled seven small human trials with a PASI standardised mean difference of −0.83 (95% CI −1.53 to 0.14), with high heterogeneity (I² 85%) and a confidence interval that includes zero beside p = 0.02 (Zhang et al. 2022).
- People with psoriasis have higher rates of heart events in observational cohorts. The 2022 pooled estimate for moderate-to-severe psoriasis was RR 1.41 (95% CI 1.31 to 1.52), but cohort studies cannot prove that the skin disease causes the heart risk (Frontiers in Cardiovascular Medicine 2022).
- Money trail: Of the seven sources we graded, none reports manufacturer funding in its own statement. The biologic guideline's funding was not re-verified in this pass. The curcumin review is backed by Chinese national and Shanghai municipal grants. The 2025 supplement network meta-analysis is supported by a Chinese provincial traditional-medicine administration. The trials inside these reviews, and the sponsors of the biologic trials, were not traced in this draft.
Independent evidence review · Prescription medicine and supplements
Biologic medicines and topical treatments are the established route for plaque psoriasis, and the specialist guidance we could read supports using licensed biologics for eligible adults. The supplements people most often try do not have reliable independent evidence behind them. Fish oil and oral vitamin D show no clear benefit in the trials we could open. Curcumin shows a possible effect in small, low-quality trials. Our confidence: moderate that fish oil and vitamin D do little for skin; low for curcumin; moderate that psoriasis is linked to higher cardiovascular risk in cohort data, though causation is unproven. The NICE topical and biologic recommendations could not be opened for this draft, so they are not quoted here.
Table of contents
- Evidence summary
- What psoriasis is
- How it works
- What works and what does not
- Benefits by claim
- Risks and all side effects
- All interactions
- Who should take extra care
- Doses studied and treatment routes
- Follow the money: who funds the guidance and the trials
- Related research
- Frequently asked questions
- Sources and funding notes
Evidence summary
| Claim | Evidence | Source | Funding / conflict | Strength |
|---|---|---|---|---|
| Biologics are an option for eligible adults with plaque psoriasis | Guideline recommendation to offer any currently licensed biologic to adults who meet the criteria, with a decision aid to guide the choice. | BAD 2020 | Funding not re-verified in this pass; declarations are in an appendix we did not open. | Moderate |
| Fish oil reduces psoriasis severity | 3 RCTs, 337 people, PASI MD −0.28 (95% CI −1.74 to 1.19). Authors conclude the evidence "does not support the use" of fish oil. | BMC CAM 2019 | No funding declared. | Insufficient |
| Oral vitamin D reduces psoriasis severity | 4 RCTs, 333 people, PASI WMD −0.32 (95% CI −1.17 to 0.53), not significant. | PLoS One 2023 | No specific funding; no competing interests declared. | Weak |
| Curcumin reduces psoriasis severity | Seven human trials pooled; SMD −0.83 (95% CI −1.53 to 0.14); heterogeneity 85%. Mouse data are described but were not extracted. | Zhang et al. 2022 | Chinese national and Shanghai municipal science grants; no conflicts declared. | Weak |
| Curcumin lowers IL-22 levels | Curcumin with conventional therapy reduced IL-22 (MD −3.47, 95% CI −5.03 to −1.91) in a network meta-analysis of 21 RCTs. No PASI confidence interval reported for curcumin. | Frontiers in Nutrition 2025 | Chinese provincial traditional-medicine administration grant; no conflicts declared. | Weak |
| Psoriasis is linked to higher cardiovascular events | 31 cohort studies, 665,009 patients: RR 1.18 (1.13 to 1.24) for mild and 1.41 (1.31 to 1.52) for moderate-to-severe disease. | Frontiers in Cardiovascular Medicine 2022 | No funding statement found in the text we read; no conflicts declared. | Risk (association) |
| Nail changes signal psoriatic arthritis | Nail changes in 68.6% of people with psoriatic arthritis vs 40.5% without, in a German cohort cited by a narrative review. | Busse & Liao 2010 | No funding or conflicts statement found; journal funding not verified. | Moderate (narrative) |
Independent evidence and credibility scorecard
Independence tiers: 1 = no identifiable financial stake in the outcome (government or academic funding with no industry tie); 2 = indirect or undeclared ties, or a funding statement we could not complete; 3 = clear financial or ideological stake, short of being the seller; 4 = produced, funded or sponsored by the maker or seller. Credibility runs from A (highest) to D.
| Source | Who funds it | Country | Independence tier (1–4) | Credibility (A–D) | Why it would tell the truth / residual bias |
|---|---|---|---|---|---|
| BAD biologic guideline 2020 | Not re-verified in this pass; the authors' declarations are in an appendix we could not open | UK | 2 | B | A national specialist body with a clinical duty to be accurate. Residual bias: the society's own finances and the authors' ties to drug makers were not verified. |
| Fish oil meta-analysis 2019 | None declared | Not verified (journal and author affiliations not captured) | 2 | B | Uses a standard risk-of-bias tool and reports a null result. Only 3 of 13 trials had usable data, so the pooled result is fragile. |
| Vitamin D meta-analysis 2023 | No specific funding; no competing interests declared | Not verified | 2 | B | No funding to protect and a null result. Small pooled sample (333 people across 4 trials). |
| Curcumin review 2022 (Zhang et al.) | Chinese National Natural Science Foundation and other national, municipal and university grants | China | 1 | B− | Public funding and no declared conflicts. Residual bias: heterogeneity (I² 85%) and a CI that includes zero beside p = 0.02. |
| Supplement network meta-analysis 2025 | Heilongjiang Provincial Administration of Traditional Chinese Medicine; funder had no role in design or analysis | China | 2 | B− | Pre-registered (INPLASY). Residual bias: a traditional-medicine body funds research that favours traditional-medicine products. |
| Cardiovascular cohort meta-analysis 2022 | No funding statement found in the text we read | Not verified | 2 | B− | Large pooled sample (665,009 patients). Observational designs leave confounding and reverse causation open, and the funding gap is itself a flag. |
| Busse & Liao 2010 narrative review | No funding statement found; no conflicts declared | Not verified (authors' affiliation not checked) | 2 | C | Clinical narrative, not a systematic review, and dated 2010. Useful for signs to look for, not for prevalence. |
Note on clustering: no source we opened declares a commercial funder. Two sources are Chinese-funded, one is UK guidance, and three report no funding statement in the text we read. No manufacturer-funded source was in our opened set, but that reflects what we could open, not proof that none exists.
Research funding at a glance
7 sources graded. The counts below are the independence tiers assigned in the scorecard above. They count sources, not funding amounts or evidence quality.
Public funding alone does not prove independence, and commercial funding alone does not prove a claim false. Named funders, countries and relationships are in the scorecard and source notes.
What psoriasis is
The clinical focus of this article is plaque psoriasis, the form that specialist guidance most often addresses. The BAD guideline states its recommendations for adults with plaque psoriasis who meet the criteria for biologic therapy (BAD 2020). Other recognised forms, such as guttate, pustular, inverse and erythrodermic psoriasis, are not covered by any source we opened, so we do not describe them in detail here.
Psoriasis is often linked to joint disease. The psoriatic arthritis section below covers the link.
How it works
We did not open a mechanistic review for this draft, so we do not explain the immune pathway. The one mechanistic signal we can report from an opened source is the IL-22 marker: the 2025 network meta-analysis reports that curcumin with usual treatment lowered IL-22 (Frontiers in Nutrition 2025). A lower marker in a trial is not the same as a better skin outcome, so we weigh the PASI endpoint more heavily.
What works and what does not
| Claimed benefit | Verdict | Evidence | Key caveat |
|---|---|---|---|
| Licensed biologics for eligible adults | WORKS (guideline-backed) | Specialist recommendation (BAD 2020) | Choice guided by a decision aid; trial sponsors not traced in this draft |
| Fish oil for psoriasis | DOES NOT SHOW BENEFIT | Pooled PASI MD −0.28 (95% CI −1.74 to 1.19) (BMC CAM 2019) | Only 3 usable trials; we did not open the later reviews that report mixed results |
| Oral vitamin D for psoriasis | DOES NOT SHOW CLEAR BENEFIT | WMD −0.32 (95% CI −1.17 to 0.53) (PLoS One 2023) | Four trials; the authors say they agree with a 2021 Nutrition meta-analysis that we could not open |
| Curcumin for psoriasis | MIXED / UNPROVEN | SMD −0.83 (95% CI −1.53 to 0.14) across seven human trials (Zhang 2022) | Turmeric and curcumin preparations differ; heterogeneity is high |
Benefits by claim
Do biologics work for psoriasis?
The BAD 2020 rapid update recommends that adults who meet the criteria can be offered any currently licensed biologic as first-line therapy, with the choice made using a decision aid (BAD 2020). We could not open the NICE technology appraisals that set reimbursement for individual biologics, so we do not compare specific drugs in this article.
Does fish oil help psoriasis?
Not on the evidence we could open. A 2019 meta-analysis pooled the three RCTs with usable data (337 people). The result was not significant, and the authors wrote that "the current evidence does not support the use of fish oil supplement in treating psoriasis" (BMC CAM 2019). Later reviews were not opened for this draft, so the question is not fully closed.
Does vitamin D help psoriasis?
The 2023 meta-analysis of oral vitamin D pooled four RCTs (333 people) and found a non-significant PASI difference of −0.32 (95% CI −1.17 to 0.53). The authors reported no specific funding and no competing interests (PLoS One 2023). The authors say their findings agree with a 2021 meta-analysis in Nutrition that we could not open, so its figures are not reported here. Secondary time points in the same review were borderline (3 months WMD −1.18, p = 0.05; 6 months WMD −1.14, p = 0.05), and the authors note these are not stable on sensitivity analysis.
Does curcumin help psoriasis?
Curcumin is the most promising of the three supplements, but the evidence is weak. The 2022 review pooled seven human trials and found a PASI standardised mean difference of −0.83 (95% CI −1.53 to 0.14). Those figures carry several problems. Heterogeneity is high (heterogeneity 85%), the confidence interval touches zero while the p-value is 0.02. The 2025 network meta-analysis of 21 RCTs reported an IL-22 reduction with curcumin but gave no confidence interval for its PASI effect (Frontiers in Nutrition 2025).
Does psoriasis raise the risk of heart disease?
Observational data say yes, but causation is not established. A 2022 meta-analysis of 31 cohort studies (665,009 patients) found RR 1.18 (95% CI 1.13 to 1.24) for mild psoriasis and RR 1.41 (95% CI 1.31 to 1.52) for moderate-to-severe psoriasis for adverse cardiovascular outcomes. The authors did not report a funding statement, and they declared no conflicts (Frontiers in Cardiovascular Medicine 2022). In plain terms, people with more severe skin disease had about 40% higher rates of these events in the cohorts, but cohort studies cannot separate the skin disease from smoking, weight, diabetes or other shared causes.
Is psoriatic arthritis linked to the skin disease?
Yes. In a narrative review, a German study of 1,511 patients is cited: nail changes were seen in 68.6% of people with psoriatic arthritis vs 40.5% of those without (Busse & Liao 2010). It is an educational review from 2010, so its numbers should be read as clues, not as prevalence figures. The BAD guideline's first-line advice for psoriatic arthritis is covered above (BAD 2020).
Risks and all side effects
Biologics and infection
The BAD guideline covers vaccine timing for people on biologics, but we could not read that section in the text we opened, so we do not quote it. Ask the prescribing team before any vaccine.
Steroid creams
We could not open the NICE topical-treatment recommendations, so we cannot quote their limits on steroid strength, site or duration here. Ask a clinician for the local rules before using a strong steroid on the face or skin folds.
Supplements
We did not extract harm data from the supplement reviews, so we cannot give a safety profile for fish oil, vitamin D or curcumin from this draft. Absence of reported harm in small trials would not show that a product is safe, and we have not checked product purity or contamination for any of these supplements.
All interactions
We did not open a drug-interaction source for biologics, topical steroids or the three supplements in this draft. Ask a pharmacist to check any supplement against your prescribed medicines before you start it.
Who should take extra care
We did not open a source that sets out contraindications for these treatments in pregnancy, breastfeeding or children. The BAD guideline covers adults and young people, and the NICE text, which we could not open, covers children's licensing. People with infections, people planning a vaccine, and people with heart disease or diabetes should involve their own clinician before changing treatment.
Doses studied and treatment routes
We did not extract doses from the fish oil or vitamin D trials. We did not extract the preparations or doses used in the curcumin trials, so no dose can be given from this review. The 2025 network meta-analysis pooled 21 RCTs but did not report the doses in our extract. For prescribed treatments, the route and dose come from the prescriber and product label, not from this article.
Follow the money: who funds the guidance and the trials
Who funds the guidance
The BAD biologic guideline's funding was not re-verified in this pass. The authors point readers to an appendix for declarations that we could not open (BAD 2020). We did not verify the society's own income or any drug-maker payments to its members.
Who funds the trials
Two of the four supplement sources report public funding (Chinese national and provincial grants). The fish oil and vitamin D meta-analyses declare no funding. The cardiovascular cohort meta-analysis has no funding statement in the text we read. We could not trace the sponsors of the individual biologic trials. This gap matters most for the biologic claims, which rest on the guideline rather than on trials we could check.
Who makes the products
Fish oil, vitamin D and curcumin are sold as supplements by many companies. We did not trace the market leaders, their owners or their revenues, and we make no claim about any seller. Supplement trials that use a company's product should be read with that company in mind.
Documented integrity events
We did not check regulator or enforcement records for psoriasis supplements or biologics in this draft.
Related research
- Omega-3: Fish Oil, Krill, Algal — Which Form Actually Works
- Vitamin D: D2 vs D3, Deficiency, Benefits and Safety
- Eczema Supplements: Evidence, Uncertainty and Safety
- Eczema Prevention and Management: Evidence and Safety Guide
- Rheumatoid Arthritis: DMARD Guidance and Supplement Evidence
- Autoimmune Disease and the Heart: Inflammation, Clots, Vascular Risk and Medicine Safety
- Atherosclerosis: Plaque, Clinical Risk, Treatment and Funding of the Evidence
- Cardiovascular Risk Calculators: PREVENT, QRISK3, SCORE2 and Their Limits
- Diabetes and Heart Disease: Cardiovascular Risks, Treatment Purposes and Warning Signs
- Collagen: Skin, Joint and Bone Evidence, Risks and Funding
Frequently asked questions
Does fish oil clear psoriasis?
No. The 2019 meta-analysis of three usable trials found a non-significant PASI change (−0.28, 95% CI −1.74 to 1.19), and its authors concluded that the evidence "does not support the use" of fish oil (BMC CAM 2019).
Is vitamin D good for psoriasis?
The 2023 meta-analysis of four oral vitamin D trials found no significant improvement (WMD −0.32, 95% CI −1.17 to 0.53). The authors declared no specific funding and no competing interests (PLoS One 2023).
Does curcumin work for psoriasis?
Possibly, but the evidence is weak. Seven small human trials pooled to an SMD of −0.83 (95% CI −1.53 to 0.14), with high heterogeneity and reporting errors. The review was publicly funded and declared no conflicts (Zhang 2022).
Are biologics recommended for psoriasis?
The UK specialist dermatology guidance says adults who meet the criteria can be offered any currently licensed biologic, with a decision aid to guide the choice (BAD 2020). Talk to your dermatologist about whether you qualify.
Does psoriasis increase the risk of heart attack and stroke?
Cohort data show higher rates of cardiovascular events, with RR 1.41 (95% CI 1.31 to 1.52) for moderate-to-severe psoriasis across 31 studies (Frontiers in Cardiovascular Medicine 2022). These are associations, and shared risk factors may explain part of them.
Can psoriasis cause arthritis?
Psoriasis is linked to psoriatic arthritis. A narrative review cites a German study finding nail changes in 68.6% of people with psoriatic arthritis vs 40.5% without (Busse & Liao 2010). Joint symptoms should be checked by a clinician.
Can curcumin be taken with psoriasis medicine?
We did not open an interaction source for curcumin, so we cannot say. Ask a pharmacist to check any supplement against your prescribed medicines before you start it.
Sources and funding notes
Could not verify: the BAD 2020 rapid update wording, its psoriatic arthritis advice and its funding (publisher returned 403, PubMed returned 429, and the search budget ran out in this pass), the NICE CG153 psoriasis guideline and NICE biologic appraisals (the NICE pages returned access refusals), the Cochrane topical-treatment reviews, the 2021 vitamin D meta-analysis in Nutrition, a 2018 psoriatic arthritis prevalence meta-analysis, the sponsors of individual biologic trials, the BAD appendix of declarations, and the supplement market. Several PubMed and Cochrane pages returned rate-limit responses during drafting. No figure from the unopened 2021 paper is quoted.
- British Association of Dermatologists guidelines for biologic therapy for psoriasis 2020: a rapid update, British Journal of Dermatology — specialist guideline; funding not re-verified in this pass.
- Effects of fish oil supplement on psoriasis: a meta-analysis of randomized controlled trials, BMC Complementary and Alternative Medicine 2019 — meta-analysis; no funding declared.
- Efficacy and safety of vitamin D supplementation on psoriasis: a systematic review and meta-analysis, PLoS One 2023 — meta-analysis; no specific funding; no competing interests.
- Efficacy and safety of curcumin in psoriasis: preclinical and clinical evidence and possible mechanisms (Zhang et al.), Frontiers in Pharmacology 2022 — review; National Natural Science Foundation of China and other public grants; no conflicts declared.
- Effectiveness and safety of dietary supplements in the adjunctive treatment of psoriasis: a systematic review and network meta-analysis, Frontiers in Nutrition 2025 — network meta-analysis; Heilongjiang Provincial Administration of Traditional Chinese Medicine (ZHY2025-020); no conflicts declared; INPLASY-registered.
- Psoriasis Increased the Risk of Adverse Cardiovascular Outcomes: A Systematic Review and Meta-Analysis of Cohort Studies, Frontiers in Cardiovascular Medicine 2022 — meta-analysis of 31 cohorts; no funding statement found in the text; no conflicts declared.
- Busse K, Liao W. Which Psoriasis Patients Develop Psoriatic Arthritis? Psoriasis Forum 2010 — narrative review; no funding statement found; no conflicts declared.
Educational research reviewed 9 October 2026. This article is not medical advice; talk to a qualified clinician or pharmacist before starting, stopping or combining treatments.
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