Supplementation with N-3 and N-6 polyunsaturated fatty acids: Effects on lipoxygenase activity and clinical symptoms of pruritus in hemodialysis patients

Objective: To investigate the effect of supplementation with different sources of oils rich in long chain fatty acids, ie, fish oil (FO) and safflower oil (SO), on the production of leukotriene B-4 (LTB4) by polymorphonuclear leukocytes (PMNLs) in hemodialysis patients and the consequent effects on the symptoms of pruritus. Design: Randomized, prospective, double-blind study for 2 treatment groups. Setting: Three Medical Center-affiliated units. Patients: Twenty-two patients on maintenance hemodialysis, of both sexes, age greater than or equal to 20 years with complaint of dry and/or itchy skin. Intervention: Two groups of patients receiving daily supplements of 6 g ethyl ester of FO or SO for 16 weeks. Main outcome measures: Red blood cell (RBC) fatty acid profile, LTB4 production by PMNLs, and pruritus symptoms at baseline and after supplementation. Results: After supplementation, the FO group had a higher RBC 22:6n3, total n-3 fatty acids, and ratio of total n-3 to total n-6 fatty acids (P < .05) than the SO group. The change in LTB4 production (pg/mL) from baseline to week 16 was 240.7 +/- 200.2 to 29.2 +/- 14.6 in the FO group and from 171.1 +/- 121.7 to 31.9 +/- 14.7 in the SO group. The overall pruritus score change was 16.7 +/- 11.4 to 8.9 +/- 9.2 in the FO group and from 17.5 +/- 8.8 to 13.1 +/- 5.6 in the SO group. FO supplementation did not result in a significant specific effect on LTB4 production by the PMNLs. There was a nonsignificant decrease in the pruritus scores that could be clinically significant and important to patients suffering with this condition. Conclusion: Supplementation with FO results in significant incorporation of n-3 fatty acids in the RBCs. Intervention with both FO and SO resulted in a nonsignificant improvement of clinical symptoms of pruritus and a nonsignificant reduction in LTB4 production by PMNLs in the hemodialysis patients. The percent decrease in total puritus score was greater for the FO group compared with the SO group. (C) 2004 by the National Kidney Foundation, Inc.