Dietary Flax Oil Reduces Renal Injury, Oxidized LDL Content, and Tissue n-6/n-3 FA Ratio in Experimental Polycystic Kidney Disease

Key Findings

The Han:SPRD-cy model of polycystic kidney disease (PKD) can be ameliorated with both soy protein- and flaxseed based diets. In both instances, this was associated with the alteration of the renal and hepatic PUFA proportion, with evidence of a reduced conversion of linoleic acid (LA) to arachidonic acid (AA) for animals on a soy diet and an increase of n-3 FA with flaxseed.  To test the hypothesis that amelioration of this disease by the administration of dietary flaxseed is related to changes in PUFA composition, this study was undertaken to determine the effects of FO on renal injury in Han:SPRD-cy rat PKD. The study demonstrated that FO, either incorporated into common foodstuffs or given as a therapeutic supplement, may be of  value to in the amelioration of renal injury.

ABSTRACT

As whole flaxseed is beneficial in the treatment of experimental renal disease, we undertook a study to determine whether previously documented benefits of whole flaxseed could be reproduced with dietary low-lignan flax oil (FO), a rich source of α-linolenic acid, in experimental polycystic kidney disease.  Male offspring of Han:SPRD-cy heterozygous rats were fed a synthetic diet containing FO or corn oil (CO) for 8 wk from the time of weaning. Renal inflammation, fibrosis, proliferation, cystic change, and oxidized-LDL were assessed morphometrically.  Hepatic and renal lipid composition was assessed using GC. FO feeding produced hepatic and renal enrichment of n-3 PUFA and an increase in C18:>C18 PUFA ratios (18-carbon PUFA compared to longer-chain PUFA), with a reduction in proportion of hepatic long-chain PUFA. The FO-based diet was associated with lower mean cystic change by 29.7% (P = 0.018), fibrosis by 21.7% (P = 0.017), macrophage infiltration by 31.5% (P < 0.0001), epithelial proliferation by 18.7% (P = 0.0035), and ox- LDL detection by 31.4% (P < 0.0001) in Han:SPRD-cy heterozygotes.  Serum creatinine was significantly lower in FO-fed diseased animals. A small hypocholesterolemic effect was noted in all animals fed FO. FO feeding moderates renal injury, modifies the profile of substrates available for elongation to eicosanoid precursors, and inhibits the elongation of C18 PUFA in this model. The consumption of FO-based products may prove a more practical way of obtaining health benefit than attempts to increase dietary content of unrefined seed.