9-cis-Rich β-Carotene Powder of the Alga Dunaliella Reduces the Severity of Chronic Plaque Psoriasis: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

Background: Synthetic retinoids are one of the mainstay treatments of psoriasis. However, their use is occasionally limited by adverse effects, especially mucocutaneous, hepatic, and lipid profile toxicity. Thus, a search for retinoid metabolites that are both safe and active is essential. The alga Dunaliella bardawil is a natural source of the retinoid precursor 9-cis beta-carotene that has a good adverse effect profile. Objective: To test the effect of the alga Dunaliella bardawil on psoriasis. Methods: Thirty-four adult patients with mild, chronic, plaque-type psoriasis were included in this monocentric, prospective, randomized, double-blinded plot study. Patients received either capsules of the alga D. bardawil or starch powder capsules, as the placebo, for 12 weeks. The response to treatment was evaluated by changes in Psoriasis Area and Severity Index (PASI) and Dermatology Life Quality Index (DLQI) scores. Safety of the treatment was evaluated. Results: At the end of 6 weeks, the reduction in the mean PASI score was significantly higher in the Dunaliella group than in the placebo group (61.3% vs 34%, respectively, p = 0.002). The DLQI change did not reach significance (8.5% and 5.9% in the Dunaliella and in the control group, respectively, p = 0.9). We observed no significant change in the liver function tests or in the lipid profile. Conclusions: 9-cis beta-carotene, in the form of D. bardawil, is an effective and safe treatment for patients with mild, chronic, plaque-type psoriasis. A larger study is warranted.