Background: Previous clinical trials with evening primrose oil in atopic dermatitis (AD) treatment have shown different results. In addition, the optimal dose and duration of treatment with evening primrose oil have not yet been determined.
Objective: The aim of this study is to investigate the dose-response treatment effects of evening primrose oil on clinical symptoms of AD and serum concentrations of polyunsaturated fatty acids.
Methods: Forty AD patients were enrolled for the study and randomly divided into 2 groups: those who received evening primrose oil 160 mg daily for 8 weeks and those who received 320 mg of evening primrose oil twice daily for 8 weeks. We evaluated the Eczema Area Severity Index (EASI) scores of all AD patients at weeks 0, 2, 4 and 8. In addition, we measured the levels of serum fatty acids, including C16 : 0 (palmitic), C18 : 2n (linoleic), C18 : 3n (linolenic) and C20 : 4 (arachidonic acid) using gas chromatography.
Results: The serum fatty acid levels C18 : 3n and C20 : 4 were higher in the 320 mg group than in the 160 mg group, with statistical significance. After evening primrose oil treatment, EASI scores were reduced in the 2 groups. The improvement in EASI scores was greater in the 320 mg group than in the 160 mg group. There were no side effects seen in either group during the study in the 2 groups.
Conclusion: The results of this study suggest that the 320 mg and 160 mg groups may be equally effective in treating AD patients and show dose-dependent effects on serum fatty acid levels and EASI scores.
Keywords: Atopic dermatitis; Evening primrose oil; Gamma-linolenic acid.