In a placebo-controlled clinical trial, the dietary supplement XP-828L (commercialized as Dermylex) demonstrated potential to reduce symptoms associated with mild-to-moderate psoriasis at a dose regimen of 5 g daily for 56 days. However, recent in vivo data in humans and animals suggest a daily dose of 800 mg could be more efficient than a 5-g dose. However, no well-structured clinical study has confirmed this hypothesis. The goal of the present study is to examine the effect of XP-828L at a daily dose of 800 mg on the quality of life and disease severity in patients with mild-to-moderate psoriasis. XP-828L at 800 mg per day (n=16) or placebo (n=10) was given orally for 56 days. Efficacy was measured by the Dermatology Life Quality Index (DLQI), Psoriasis Area and Severity Index (PASI), and itching sensation scores at day 1 and day 56. The DLQI and PASI scores and itching sensation decreased significantly by day 56 in subjects taking XP-828L compared to placebo (p less than 0.05). In summary, daily administration of 800 mg XP-828L for 56 days is adequate to improve the quality of life and decrease disease severity in patients with mild-to-moderate psoriasis.