Benefits of omega-3 fatty acids in kidney disease patients

Individuals with kidney disease offer a unique group in which to study the potential benefits of marine-derived omega-3 fatty acids, especially given their inadequate dietary intake 1 and numerous complications. However, research in this area is still in its early stages.

Interest in applying the anti-inflammatory effects of omega-3 fatty acids to kidney disease has actually existed for some time. Based on randomized, controlled data, omega-3 fatty acids in fish oil are now routinely used to prevent the progression of IgA nephropathy, the world's most common glomerulopathy. The most famous such study was performed by the Mayo Collaborative Group, which found that providing 1.9 grams eicosapentaenoic acid (EPA) and 1.4 grams docosahexaenoic acid (DHA) daily to proteinuric IgA nephropathy patients with moderate disease reduced the risk of dialysis or death over five years (p=0.006) 2.

Omega-3 fatty acid supplementation has been shown in preliminary studies to reduce the risk of arteriovenous graft thrombosis 3, perhaps by inhibiting the inflammatory pathway and secretion of platelet-derived growth factor at the anastomosis site. Larger, ongoing randomized trials in Canada and Australia are attempting to confirm whether omega-3 fatty acids can in fact extend the life of arteriovenous grafts and fistulas.

An inverse relationship between omega-3 fatty acid consumption and/or blood levels and mortality has been observed 4,5. Data on cardiovascular outcomes, the principal cause of death in dialysis patients, is sparse. Svensson et al. randomized 206 prevalent hemodialysis patients to 1.7 grams omega-3 fatty acids in fish oil form vs. placebo 6. They found that compared to placebo, fish oil supplementation did not improve the primary outcome, which was a composite of cardiovascular events. They did, however, report a protective effect on myocardial infarctions. Further better-powered studies in this area will be needed to resolve the question of whether omega-3 fatty acids can improve hard outcomes in dialysis patients.

With the growing evidence that omega-3 fatty acids play important roles in immune modulation, electrophysiology, and gene translation and signal transduction, we should expect more kidney disease-related research into the effects of omega-3 fatty acids in areas such as insulin resistance and diabetic nephropathy 7, cardiovascular disease, systemic inflammation and bone and muscle health.

References

  1. Friedman AN, Moe SM, Perkins SM, Li Y, Watkins BA. Fish consumption and omega-3 fatty acid status and determinants in long-term hemodialysis. Am J Kidney Dis 2006;47:1064-71.
  2. Donadio JV Jr, Bergstralh EJ, Offord KP, Spencer DC, Holley KE. A controlled trial of fish oil in IgA nephropathy. Mayo Nephrology Collaborative Group. N Engl J Med 1994;3:1227-9.
  3. Schmitz PG, McCloud LK, Reikes ST, Leonard CL, Gellens ME. Prophylaxis of hemodialysis graft thrombosis with fish oil: double-blind, randomized, prospective trial. M Am Soc Nephrol 2002;13:184-90.
  4. Friedman AN, Saha C, Watkins BA. Feasibility study of erythrocyte long-chain omega-3 polyunsaturated fatty acid content and mortality risk in hemodialysis patients. J Ren Nutr 2008;18:509-12.
  5. Kutner NG, Clow PW, Zhang R, Aviles X. Association of fish intake and survival in a cohort of incident dialysis patients. Am J Kidney Dis 2002;39: 1018-24.
  6. Svensson M, Schmidt EB, Jørgensen KA, Christensen JH. OPACH Study Group. N-3 fatty acids as secondary prevention against cardiovascular events in patients who undergo chronic hemodialysis: a randomized, placebo-controlled intervention trial. Clin J Am Soc Nephrol 2006;1:780-6.
  7. Garman JH, Mulroney S, Manigrasso M, Flynn E, Maric C: Omega-3 fatty acid rich diet prevents diabetic renal disease. Am J Renal Physiol 2009;296:F306-16.

Key Points

  • These fatty acids may have important benefits for a variety of kidney disease-related complications.
  • The fatty acids are routinely used to prevent progression of IgA nephropathy.
  • The omega-3 fatty acids may reduce the risk of arteriovenous graft thrombosis.
  • The cardiovascular and reduced mortality benefits of omega-3 fatty acids are an area of active investigation.