Fish oils and glomerulonephritis.

Sir, I agree that fish oils administered at high dosage will reduce access thrombosis [1] and that fish oils lower serum triglycerides [2] and so protect against atherosclerosis. However, the evidence that fish oils really benefit patients with glomerulonephritis deserves closer scrutiny. In spite of impressive lymphocyte suppression in mice or in vitro, results accumulated over two decades show only a modest benefit of fish oils on eicosanoid production and cytokine release and on the clinical status of persons with rheumatoid arthritis, and other Th-1 lymphocyte-mediated pathologies [3]. We were reliably informed that fish oils could reduce the decline of creatinine clearance, and yet not reduce proteinuria significantly [4]. At the ISN IgA Nephropathy Conference in Leiden in 1998 we noted that fish oils did not reduce urine thromboxanes, as anticipated. Now Grimble [5] reports that in UK subjects, fish oils will increase serum TNFa in half, and lower it in the other 50%! Nephrologists should stop extrapolating results from dietary experiments in mice to what might happen in humans, and carry out more detailed investigations of their own patients who participate in trials.