Topical fish oil in psoriasis—a controlled and blind study

Omega-3 polyunsaturated fatty acids compete with arachidonic acid as substrates for lipoperoxidases, which transform them into leukotrienes with low biological activity. As this process, in skin, may benefit psoriatic patients, a randomized controlled single blind-study was carried out on a sample of 25 patients. In the study fish oil (FO) was compared with liquid paraffin (LP); both were topically applied and administered daily for 6 h under an occlusive dressing: over a 4-week period. Evaluations were performed weekly assessing erythema, scaling, plaque thickness (induration) and itching. The results showed statistically significant improvement in erythema and scaling for both treatments compared to basal values; significant differences between treatments were achieved in scaling but not in erythema. Compared to baseline, FO significantly improved plaque thickness while LP did not. After 4 weeks, FO proved to the significantly better than LP. All patients accepted the treatment despite its unpleasant smell. Irritation and a burning sensation were reported in the FO treated plaque of one patient. This adverse effect reverted after completing the treatment. These findings demonstrate that topical FO shows a better performance than LP under an occlusive dressing.