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Title: DIETARY FLAXSEED MEAL REDUCES PROTEINURIA AND AMELIORATES NEPHROPATHY IN AN ANIMAL MODEL OF TYPE II DIABETES MELLITUS

Author
item VELASQUEZ, MANUEL - GW UNIV, WASH,DC
item Bhathena, Sam
item RANICH, TEDINE - GW UNIV, WASH, DC
item SCHWARTZ, ARNOLD - GW UNIV, WASH, DC
item KARDON, DAVID - GW UNIV, WASH, DC
item ALI, ALI - MD/VA MILK PROD,LAUREL,MD
item HAUDENSCHILD, CHRISTIAN - AM RED CROSS,ROCKVILLE,MD
item HANSEN, CARL - NIH,BETHESDA,MD

Submitted to: Kidney International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2003
Publication Date: 6/1/2003
Citation: Velasquez, M.T., Bhathena, S.J., Ranich, T., Scwartz, A.M., Kardon, D.E., Ali, A.A., Haudenschild, C.C., Hansen, C.T. 2003. Dietary flaxseed meal reduces proteinutria and ameliorates nephropathy in an animal model of type II diabetes mellitus. Kidney International. 64:2100-2107.

Interpretive Summary: We studied the effects of dietary soybean and flaxseed meal on plasma and urine parameters of renal disease and on kidney morphology in SHR/N-cp rat, which is a recognized model of type II diabetes and also develops nephropathy that resembles diabetic nephropathy in humans. We fed either 20% casein, 20% soy protein concentrate or 20% flaxseed meal to SHR/N-cp rats for six months. We observed that dietary protein source had no significant effect on plasma glucose, creatinine or urine urea excretion. However, feeding flaxseed meal significantly lowered plasma insulin and decreased urine protein excretion compared to feeding casein or soy protein. Flaxseed meal also had protective effect on kidney, in that, the rats fed flaxseed meal had significantly fewer number of abnormal glomeruli and lower tubulointerstitial score. We conclude that substitution of animal protein like casein with plant protein such as flaxseed meal has beneficial effect in reducing renal disease in diabetic animals. These data will help nutritionists, dietitians and medical professionals in recommending the type of dietary protein for the proper nutrition of the general population, to medical professionals involved in the treatment of subjects with diabetes and renal disease, and also to the food processing industry.

Technical Abstract: The effect of dietary soy protein and flaxseed meal on renal function and nephropathy was studied in obese SHR/N-cp rats, an animal model of type II diabetes that consistently develops nephropathy resembling diabetic nephropathy. The rats were fed either 20% casein, 20% soy protein concentrate or 20% flaxseed meal for six months. Plasma was analyzed for glucose, insulin and creatinine. Plasma and urine were also analyzed for renal function, creatinine clearance, urea excretion and protein excretion. Kidneys were examined for histological evaluation. There was no significant effect of soy protein or flaxseed meal compared to casein on plasma glucose, but flaxseed meal feeding significantly decreased plasma insulin compared to casein or soy protein. Urinary protein excretion was also significantly lower in rats fed flaxseed meal than in those fed casein or soy protein concentrate. Histological analysis of kidneys showed decreased glomerular lesion and lower tubulointerstitial score in rats fed flaxseed meal compared to those fed casein or soy protein concentrate. In conclusion, dietary protein substitution with flaxseed meal reduces proteinuria and renal glomerular and tubulointerstitial lesions in obese SHR/N-cp rats and that flaxseed meal is more protective than soy protein in reducing proteinuria and renal abnormality. The reduction in proteinuria and renal injury appears to be independent of the amount of protein intake and glycemic control. Which dietary component(s) in flaxseed meal is (are) responsible for the renal protective effects remains to be determined.