Low blood levels of long-chain n-3 polyunsaturated fatty acids in US hemodialysis patients: clinical implications.

BACKGROUND Cardioprotective and other clinical benefits of long-chain n-3 polyunsaturated fatty acids (PUFA) are inversely related to dietary intake and hence blood content. We therefore investigated, in the first study of its kind, the blood content and distribution of these fatty acids in a large representative population of US hemodialysis patients. METHODS Frozen sera were obtained from 400 individuals who were part of a large, contemporary, representative cohort of US incident hemodialysis patients. Long-chain n-3 PUFA were measured in total serum lipids and in the neutral and polar serum fractions using gas chromatography and solid phase extraction techniques. Mean long-chain n-3 PUFA levels were compared to levels in other dialysis and nondialysis populations from published reports. RESULTS The study population was qualitatively similar to the overall US hemodialysis population in terms of major clinical characteristics. Long-chain n-3 PUFA were present in the serum polar fraction, with essentially none being detected in the neutral fraction (p < 0.0001 for polar vs. neutral fractions for all three long-chain n-3 PUFA). Mean serum long-chain n-3 PUFA levels (weight percent (±SD): total 1.55 ± 0.95, polar 3.99 ± 1.45) were low compared to nondialysis and most other non-US hemodialysis cohorts. CONCLUSIONS While US hemodialysis patients have a blood distribution of long-chain n-3 PUFA that is similar to that in the general population, blood content is among the lowest recorded in the medical literature. This has implications for renal dietary recommendations and makes US patients an ideal group for testing the clinical effects of long-chain n-3 PUFA supplementation.