ROCHESTER, MINNESOTA. In 1994 researchers at the Mayo Clinic reported that fish oils (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) are effective in slowing the progression of IgA nephropathy. The follow-up period during the initial trial was 4 years. The Mayo researchers have now extended the follow-up period to 6.4 years. As in the earlier trial the patients took either placebo (olive oil capsules) or fish oil capsules providing 1.9 grams/day of EPA and 1.4 grams/day of DHA. The primary end point of the trial was an increase of 50% or more in serum creatinine and the secondary end point was the development of end-stage renal disease (ESRD).
At the end of the follow-up period 17 patients in the fish group reached the primary end point versus 29 patients in the placebo group, i.e. a 41% reduction in the number of patients experiencing an increase in serum creatinine of 50% or more. Eight patients in the fish group developed ESRD versus 19 patients in the placebo group or a 58% reduction in the number of patients whose disease progressed to ESRD. The researchers conclude that early and prolonged treatment with fish oils slows the progression of renal disease in high-risk patients with IgA nephropathy. They believe that the main mechanism by which fish oils works is through competition with arachidonic acid for the enzyme required to produce eicosanoids. Arachidonic acid is metabolized to eicosanoids that engender inflammation while fish oils result in the production of eicosanoids that combat inflammation. The "good" eicosanoids likely slow renal disease progression by reducing glomerular and interstitial inflammation, mesangial cell contractility, platelet aggregation and vasoconstriction in response to renal injury.
Donadio, JV, et al. The long-term outcome of patients with IgA nephropathy treated with fish oil in a controlled trial. Journal of the American Society of Nephrology, Vol. 10, 1999, pp. 1772-77