Possible low plasma zinc in psoriasis and the similarity of psoriasis to zinc deficiency dermatosis in animals prompted this study. Using a double-blind, cross-over design we treated 19 psoriatic outpatients with 220 mg zinc sulfate or placebo three times daily for two months. No statistically significant improvement was detected in treated patients.
Seven psoriatic inpatients had scale zinc higher than keratin zinc in five controls, whereas four patients had serum zinc lower than 12 controls. These four with low serum zinc also failed to improve on zinc therapy, although psoriatic scale zinc increased and serum zinc surpassed that of controls. These findings militate against gastrointestinal malabsorption or faulty cutaneous entry of therapeutic zinc in psoriasis. Although subcellular zinc metabolism might be abnormal in psoriasis, systemic zinc deficiency is probably not the basic error.
Voorhees JJ, Chakrabarti SG, Botero F, Miedler L, Harrell ER. Zinc Therapy and Distribution in Psoriasis. Arch Dermatol. 1969;100(6):669-673. doi:10.1001/archderm.1969.01610300019002