The effect of dietary omega-3, -6, and -9 fatty acid supplements on serum fatty acid concentrations in renal dialysis patients: Implications for immune response
Abstract •Objective: To alter the serum fatty acid and immunoglobulin concentrations of renal dialysis patients by supplementation of omega-3, -6, or -9 fatty acids during a 6-week period. •Design: Randomized before-and-after-supplementation trial. •Setting: Three dialysis centers in the Dallas, TX, methopolitan area. •Patients: Thirty-five maintenance hemodialysis patients were chosen. Subjects were identified for inclusion in the study by the following criteria: concentrations of triglycerides ( 1.70 mmol/L [150 mg/dL]) and cholesterol ( 4.66 mmol/L [180 mg/dL]), absence of insulin-dependent diabetes, and absence of liver disease. •Interventions: Patients were supplemented daily with either 3g of omega-3 MaxEPA (Seven Seas Health Care, Hull, England), 3g of omega-6 fatty acid cottonseed oil, or omega-9 fatty acid (10% of caloric intake) pecan oil. The control group received no treatment. •Main outcome measures: Fasting serum samples were obtained on days 0, 21, and 42 to determine serum concentrations of eicosapentanoic acid (EPA), docosahexanoic/myristic acids (DHA/MYR), arachidonic acid (AA), linolenic acid (LNA), linoleic acid (LA), oleic acid (OA), immunoglobulin G (IgG), immunoglobulin A (IgA), and immunoglobulin M (IgM). •Results: Twenty-eight subjects completed the study. Within the MaxEPA-supplemented (N = 5) and pecan oil-supplemented (N = 8) groups, serum EPA concentrations were significantly higher at days 21 and 42 than at day 0. Within the cottonseed oil-supplemented group (N = 8), serum EPA concentration was significantly higher at day 21 than at days 0 and 42. The serum concentrations of AA were significantly lower in the MaxEPA-supplemented and pecan oil-supplemented groups at day 21 and 42 than at day 0. No significant change was shown in serum DHA/MYR, LNA, LA, or OA concentrations from day 0 to day 42. There existed no significant difference in serum IgG, IgA, or IgM concentrations for the duration of the study. •Conclusions: Omega-3, -6, and -9 fatty acid supplements exert different effects on serum fatty acid concentrations in renal dialysis patients. These results support findings in the literature indicating that fatty acid metabolite profiles may be manipulated by diet. In turn, immune response may be altered through manipulation of eicosanoid production. Because of a compromised immune status, renal dialysis patients may be the best population for this type of research, and a comparison of such subjects with healthy volunteers is warranted.