Importance: Psoriasis is a chronic, inflammatory skin disease and has significant associated morbidity and effect on quality of life. It is important to determine whether dietary interventions help reduce disease severity in patients with psoriatic diseases.

Objective: To make evidence-based dietary recommendations for adults with psoriasis and/or psoriatic arthritis from the Medical Board of the National Psoriasis Foundation.

Evidence review: We used literature from prior systematic reviews as well as additional primary literature from the MEDLINE database from January 1, 2014, to August 31, 2017, that evaluated the impact of diet on psoriasis. We included observational and interventional studies of patients with psoriasis or psoriatic arthritis. The quality of included studies was assessed using the Newcastle-Ottawa scale for observational studies and the Cochrane Risk of Bias Tool for interventional studies. We made evidence-based dietary recommendations, which were voted on by the National Psoriasis Foundation Medical Board.

Findings: We identified 55 studies meeting the inclusion criteria for this review. These studies represent 77 557 unique participants of which 4534 have psoriasis. Based on the literature, we strongly recommend dietary weight reduction with a hypocaloric diet in overweight and obese patients with psoriasis. We weakly recommend a gluten-free diet only in patients who test positive for serologic markers of gluten sensitivity. Based on low-quality data, select foods, nutrients, and dietary patterns may affect psoriasis. For patients with psoriatic arthritis, we weakly recommend vitamin D supplementation and dietary weight reduction with a hypocaloric diet in overweight and obese patients. Dietary interventions should always be used in conjunction with standard medical therapies for psoriasis and psoriatic arthritis.

Conclusions and relevance: Adults with psoriasis and/or psoriatic arthritis can supplement their standard medical therapies with dietary interventions to reduce disease severity. These dietary recommendations from the National Psoriasis Foundation Medical Board will help guide clinicians regarding the utility of dietary interventions in adults with psoriatic diseases.