Feeding Different Omega-3 Polyunsaturated Fatty Acid Sources Influences Renal Fatty Acid Composition, Inflammation, and Occurrence of Nephrocalcinosis in Female Sprague-Dawley Rats

The general population is encouraged to increase omega-3 polyunsaturated fatty acid (n-3 PUFA) intake in order to optimize health for preventative health care. Consumers are typically unaware that different amounts, types, and structural forms of n-3 PUFA have different efficacy. Therefore, the objectives of this study were to characterize different sources of n-3 PUFAs and to determine whether consumption of these oils influences renal fatty acid composition and renal health. Lipid classes and fatty acid profile of corn (CO), flaxseed (FO), menhaden (MO), salmon (SO), tuna (TO) or krill (KO) oils were determined by thin-layer and gas chromatography. All dietary oils consisted of >65% triglyceride with the exception of KO. KO and FO also contained phospholipids. FO was rich in the n-3 PUFA, alpha-linolenic acid (18:3n-3) whereas, the marine oils were rich in the long-chain n-3 PUFAs (>18 carbons). Following characterization of the oil sources, female Sprague-Dawley rats (age 28 d) were randomly assigned (n = 10/group) to be fed a high fat 12% (wt) diet consisting of these different oil sources for 8 weeks. Rats fed MO, TO, and SO had significantly higher renal eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3) deposition and this in turn, modulated inflammatory responses. Feeding rats MO, SO and TO reduced urinary excretion of 13,14-dihydro-15-keto prostaglandin E2. Feeding rats TO and SO reduced (P ≤ 0.002) nuclear factor kappa B activity and circulating TNFα (P < 0.05). In contrast, rats consuming KO had heavier kidney weights (P < 0.001), total calcium content, and histological evidence of renal calcification and tubulo-interstitial injury. This was due to increased (P < 0.001) urinary phosphorus excretion associated with the phospholipids content of KO. The study results indicated that consumption of n-3 PUFAs influences renal health and the effects varied depending on the n-3 PUFA source consumed.