Friedman and Moe reviewed the effects of n-3 fatty acid supplementation in dialysis patients (Clin J Am Soc. Nephrol. 2006;1:182-192), emphasizing new studies since the 2005 KDOQI report. Their first conclusion was that dialysis patients were generally deficient in n-3 fatty acids, possibly due to low fish consumption. This could be related either to lower palpability of fish or its higher cost.
Although not suggested by Friedman and Moe, restriction of dietary protein prior to dialysis could be a contributor.
Overall, their review of the studies to date suggested that n-3 fatty acid supplementation at high doses can reduce triglycerides, but the effects on other lipoproteins are inconsistent. Studies looking at hematologic parameters associated with n-3 fatty acids have found no clear effects on platelet aggregation, blood viscosity, red blood cell survival, and bleeding times, even at high doses.
One study, however, revealed a one-year patency rate of 76% for new arteriovenous grafts in hemodialysis patients who took fish oil compared with a 15% rate for those who took placebo. Thus, fish oil may hold promise as an effective prophylaxis against shunt thrombosis. Poor study design and small numbers of studies limit the conclusions that can be made about immunity and inflammatory parameters in dialysis patients.
Two randomized trials comparing n-3 fatty acid supplemention and placebo have found a trend toward an improvement in pruritus symptoms in patients receiving n-3 fatty acids. Data on n-3 fatty acid supplementation have not supported concerns that they upregulate oxidative stress. Adverse effects generally have been limited to GI symptoms such as nausea, vomiting, diarrhea, and abdominal discomfort.
Friedman and Moe concluded that preliminary studies show that n-3 fatty acid supplementation benefits dialysis patients, but more studies are needed to make clinical recommendations. The effects of n-3 fatty acid supplementation were generally positive, with interpretation limited by the small number of studies, small subject number and poor study design.