Nephrocalcinosis, the accumulation of calcium (Ca) in the kidneys, is associated with multiple renal disorders including renal stones. Populations with low risk of renal stones have been shown to have a diet high in fish oil, a rich source of omega‐3 polyunsaturated fatty acids (n‐3 PUFAs). However, sources of n‐3 PUFAs differ in the amount, type, and structure. The study objective was to determine the effect of feeding different sources of n‐3 PUFAs on the development of nephrocalcinosis. Young (age 28 day) female Sprague‐Dawley rats were fed a casein diet supplemented with corn oil or omega‐3 rich oils consisting of flaxseed, krill, menhaden, salmon, or tuna oil for 12 wks. Gas chromatography showed that renal fatty acid composition reflected the fatty acid profile of the dietary oils. RT‐qPCR showed that rats fed fish oils had reduced inflammation as indicated by lower (P<0.05) COX‐2 and TGF‐β. Furthermore, rats fed salmon or tuna oil had increased (P<0.05) osteopontin (SPP1) gene expression, indicating antagonist action to renal Ca crystallization. Rats fed fish oils had lower (P<0.05) renal NFκB and prostaglandin E2 activity as determined by enzyme immunoassay. However, krill oil induced nephrocalcinosis due to the high phosphorous (P) content associated with phospholipids. Different sources of n‐3 PUFAs mitigated the effects of nephrocalcinosis, but failed to prevent nephrocalcinosis due to Ca:P imbalance.

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Polycystic kidney disease (PKD) is a genetic disorder characterized by multiple cyst formation that increases renal size, structural damage, and loss of function. Studies showed soy protein isolate (SPI) protective against chronic kidney disease and omega‐3 polyunsaturated fatty acids (n‐3 PUFAs) decrease inflammation. Few studies have examined the role of diet in PKD. The study objective was to investigate whether SPI and/or n‐3 PUFA supplementation attenuates PKD progression. Young (age 28 d) female pck rats were randomly assigned (n=12/group) to diets consisting of casein + corn oil (Casein + CO), casein + soybean oil (casein + SO), SPI + soybean oil (SPI + SO) or SPI + 1:1 soybean/salmon oil (SPI + BLEND) for 12‐weeks. Kidney weights were highest in the SPI + BLEND group. Histology showed interstitial inflammation, fibrotic changes, interstitial matrix deposition, and structural effacement due to cyst growth in all groups. Cortical cyst obstruction indicating more extensive nephron damage was only observed in the SPI + BLEND group. The SPI +BLEND group had the highest (11.78 + 0.60 mg/dL, P=0.01) and Casein + SO group the lowest (9.28 + 0.81, P=0.01) serum blood urea nitrogen. Urinary calcium and phosphorus was higher in the casein than SPI groups. There were no significant differences in serum calcium, phosphorus, uric acid, total protein or albumin. Based on the results, diet did not attenuate PKD progression.Grant Funding Source: WVU Hatch Grant H459

Polycystic kidney disease (PKD) is a genetic disorder resulting in multiple cysts that can alter kidney function leading to mineral imbalance and bone loss. In healthy female rats, soy protein isolate (SPI) and omega‐3 polyunsaturated fatty acids (n‐3 PUFA) increased bone mineral density (BMD), bone mineral content (BMC), and bone formation markers. The study objective was to investigate the effect of soy protein isolate and/or n‐3 PUFA supplementation on bone mass and strength in rats with PKD. Growing female pck rats (n=12/group) were randomly assigned to be fed soy protein isolate + corn oil (Casein + CO), casein + soybean oil (Casein + SO), soy protein isolate + soybean oil (SPI + SO) or soy protein isolate + 1:1 soybean/salmon oil (SPI + BLEND) for 12 wks. Urinary calcium (Ca) decreased (P=0.003) in the order of Casein + SO >; Casein +CO >; SPI +SO >; SPI + BLEND. Urinary phosphorus (P<0.001) decreased in the order of Casein + SO >; Casein CO >; SPI + BLEND >; SPI + SO. There were no significant differences in bone Ca, P, BMD and BMC among the diet groups. There were also no dietary effects on peak force, ultimate stiffness, ultimate bending stress, or young's modulus. Serum alkaline phosphatase was higher (P=0.003) in rats fed SPI + BLEND and SPI + SO compared to Casein + CO and Casein + SO. The SPI + BLEND group had the highest (P=0.001) femur length. Based on the study results, diet had little impact on the bone mass or strength of female rats with PKD.

Polycystic kidney disease (PKD) is a leading cause of end stage renal failure, resulting in the need for transplantation or long‐term dialysis. Inflammation is a common pathology in disease severity. Soy protein isoloate (SPI) and omega‐3 fatty acids (n‐3 PUFA’s) have been shown to have anti‐inflammatory properties. Therefore, the objective of the study was to examine the effects of SPI and/or n‐3 PUFA’s on renal inflammation in PKD. Female pck rats (age 28 d) were fed (n=12/group) diets consisting of casein + corn oil (Casein + CO), casein + soybean oil (Casein + SO), SPI + soybean oil (SPI + SO) or SPI + 1:1 soybean/salmon oil (SPI + SB) for 12‐weeks. Kidney fatty acid analysis by gas chromatography showed rats fed Casein + SO and SPI +SB diets had the higher (P = 0.02) renal alpha linoleic acid content compared to the Casein + CO and SPI + SO groups. The SPI + SB group had the highest (P < 0.001) renal docosahexaenoic acid (DHA) content. The Casein + CO group had the lowest (P < 0.001) DHA compared to the other diet groups. There were no significant differences in renal eicosapentaenoic acid content among the diet groups. Despite differences in renal n‐3 PUFA content, real time quantitative polymerase chain reaction showed no differences in relative genetic expression levels of cyclooxygenase‐2, peroxisome proliferator‐activated receptor gamma or mammalian target of rapamycin. Histological evaluation also showed no differences in renal interstitial inflammation. Based on the results, SPI and/or n‐3 PUFAs did not appear to attenuate PKD severity by reducing inflammation.