Fish Oil and Kidney Disorders

CATSKILL, NEW YORK. Patients with kidney failure require long-term hemodialysis in order to remove waste products from the blood. It is estimated that about 350,000 patients in the USA alone require regular dialysis treatments. Although modern dialysis methods are effective in cleaning up the blood they do produce side effects. Uremic pruritus or renal itch (localized or generalized itch in patients with chronic kidney disease) affects up to 80% of patients on dialysis. A recent clinical trial found that patients given 6 grams/day of fish oil had significantly less severe itching than did patients given a similar daily dose of olive oil or safflower oil.

The researchers doing the trial speculate that oils found in fish prevent itching by displacing arachidonic acid from cell membranes. Fish oils and arachidonic acid compete for the same enzymes (cyclooxygenase and lipoxygenase) used in the production of eicosanoids. If arachidonic acid "wins" more pro-inflammatory compounds (series 2 prostaglandins and series 4 leukotrienes) are produced whereas if fish oils gain the upper hand the result is the production of more anti-inflammatory compounds (prostaglandin E3 and leukotriene B5). The anti-inflammatory eicosanoids would be less likely to cause itching than would the pro-inflammatory ones.

Because dialysis patients leave some blood in the dialysis machine at each treatment they are given the hormone erythropoietin in order to stimulate the production of new red blood cells. A small pilot study involving 20 dialysis patients was recently carried out to see if fish oil supplementation would reduce the need for erythropoietin. The patients were given 6 grams/day of emulsified fish oil (3 pouches of Coromega) for 8 weeks. At the end of the study the average erythropoietin requirement had declined by 16% and serum albumin had increased by 3.6%.

Researchers at Emory University have found that dialysis patients who reported eating fish at least once in a 3-day period were about half as likely to die during the 3-year study period, as were patients who did not report any fish consumption.

Fish oils (which contain eicosapentaenoic acid and docosahexaenoic acid, also known as EPA and DHA) are generally considered safe in daily intakes of as much as 12 grams. According to the Food and Drug Administration supplementing with EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) is safe provided the combineddaily intake does not exceed 3 grams.

Note: This would correspond to about 10 grams of fish oil. There is no evidence that fish oils increase bleeding time; however, it would be prudent to adjust the dose of heparin used during dialysis if fish oil supplementation is used.

Vergili-Nelsen, JM. Benefits of fish oil supplementation for hemodialysis patients. Journal of the American Dietetic Association. Vol. 103, September 2003, pp. 1174-77

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Category: Kidney Disorders