e60 A critical literature review of the effectiveness and safety of dietary interventions for the treatment of psoriasis and psoriatic arthritis

Abstract

Background: Psoriatic arthritis (PsA) is a chronic inflammatory disease affecting up to one third of patients with skin psoriasis. The potential role of the gut microbiome in the pathogenesis of PsA has been raised, renewing interest in the potential impact of dietary interventions. The role of diet in the management of PsA is a patient priority research topic. The objective of this review is to critically appraise the evidence for the effectiveness and safety of dietary interventions in PsA. Methods: Pre-defined search terms were entered into Ovid MEDLINE, and results restricted to randomised controlled trials of dietary interventions for psoriasis and psoriatic arthritis published in English from 1990 onwards. Thirty original publications were identified and screened for eligibility using predefined criteria and 19 articles were selected for final inclusion. Results: Eleven studies investigated the effects of supplementing n-3 polyunsaturated fatty acids (PUFAs). Changes towards an anti-inflammatory lipid profile were consistently reported, however improvements to clinical manifestations of disease were inconsistent. One study investigated a low calorie, n-3 PUFA rich diet in obese patients which produced reductions in several scoring systems of disease severity. The inconsistent findings of dietary supplementation of n-3 PUFAs may be due to the use of n-6 rich PUFA oils such as soya, corn and olive oils as control substances in the selected studies which may itself exert antiinflammatory effects via their linoleic acid content. One study reported improved bioavailability of psoriasis treatments when taken with food. Five studies looked at antioxidant supplementation. Selenium supplementation alone was not an effective adjunct in treating skin disease but more promising results were observed using combinations of compounds, particularly in patients with metabolic syndrome. Improvements in serum lipid profile have been reported following antioxidant supplementation but the studies frequently did not reach statistical significance as a result of the small sample sizes and short follow-up times, thus further investigation in larger, higher powered studies is warranted and necessary to draw firm conclusions. One study investigated the effects of modulating the microbiome, with subsequent reductions in inflammatory markers. Conclusion: Improved lipid profiles, modulation of the gut microbiome, increased bioavailability of drugs and clinical improvement have all been reported in RCT's of dietary intervention in PsA but results are inconsistent due to a relative lack of RCT data and flaws in study design. No safety concerns were reported in any of the studies analysed.