Patients with psoriasis participated in a study published in the British Journal of Dermatology (June 26, 2007; e-published ahead of print). The study included 185 subjects with chronic plaque-type psoriasis affecting between 2% and 10% of total body surface area.

Participants were divided into three groups. One group received a topical placebo, while the other two groups received topical application of becocalcidiol, a vitamin D₃ analog. One treatment group received a low dose (75 mcg/g once daily), while the other received a higher dose (75 mcg/g twice daily). During the eight-week treatment phase, 26% of patients receiving the higher-dose becocalcidiol were rated as clear or almost clear of lesions according to the Physician’s Global Assessment of Overall Lesion Severity (PGA).

Additional research supports a role for vitamin D in psoriasis. A review article published in Cutis (1993;52:145–152) reported that ultraviolet radiation can be useful in relieving psoriasis symptoms. Other research has shown that serum vitamin D levels tend to be lower in patients with psoriasis (Acta Dermato-Venereologica, 1987;67[1]:65–68).

Other nutrients have also been studied in psoriasis, including fish oil. High-dose omega-3 supplementation appears to be more effective than low-dose interventions. Some studies showing minimal benefit used relatively low doses, leading some researchers to question their clinical relevance. In one study published in Clinical Investigator (1993;71:634–643), patients with psoriasis affecting at least 10% of body surface area received 100 mL per day of a lipid emulsion. The control group received an omega-6–rich emulsion, while the treatment group received an omega-3 emulsion containing 2.1 g of eicosapentaenoic acid (EPA) and 21 g of docosahexaenoic acid (DHA). Significant improvement was observed in the omega-3 group, with symptom reduction ranging from 45% to 75% within 10 days.

Dietary factors may also play a role. A study published in Acta Dermato-Venereologica (2003;83:425–429) found that a gluten-free diet was beneficial for some psoriasis patients. Another study in the British Journal of Dermatology (2006;155[6]:1165–1169) reported that psoriasis patients had higher homocysteine levels than healthy controls, and that disease severity appeared to parallel homocysteine concentrations. These findings raise the possibility that nutrients involved in homocysteine metabolism—such as folic acid, vitamin B6, and vitamin B12—may be relevant in some cases.