Flaxseed meal was found to be more beneficial on some chronic conditions such as high triglycerides and liver steatosis than soy protein meal, in a study of rats. 
Researchers from U.S. Department of Agriculture, MD, fed the rats diets containing 20% of energy from casein (control), soy protein concentrate or flaxseed meal for six months. They found that soy protein and flaxseed meal significantly could decrease plasma total cholesterol in slim rats. Flaxseed meal had significant cholesterol lowering effect in obese fat. Flaxseed meal also significantly lowered plasma triglyceride in both lean and obese rats. And, flaxseed meal significantly lowered fat deposition in livers of both groups of rats. 
Consumption of soybean and soy-based food products, as the source of plant protein, can retard the development and progression of chronic renal disease. Researchers from George Washington University Medical Center noticed that the obese spontaneously hypertensive/NIH-corpulent rat, a model of obesity and type II diabetes mellitus that consistently develops nephropathy resembling diabetic nephropathy. 
They then randomly assigned male SHR/N-cp rats to diets either 20% casein, 20% soy protein concentrate, or 20% flaxseed meal for 6 months. They found, plasma glucose levels did not differ among the three groups, but plasma insulin concentration was significantly lower in rats fed flaxseed meal than those fed either casein or soy protein concentrate. 
In addition, urinary protein excretion was significantly lower in rats fed flaxseed than in rats fed either casein or soy protein concentrate. Morphologic analysis of renal structural lesions showed that the percentage of abnormal glomeruli with mesangial expansion and the tubulointerstitial score (an index of severity of tubulointerstitial damage) were significantly reduced in rats fed flaxmeal compared to those fed casein or soy protein concentrate. 
ALL RIGHTS RESERVED ZHION 2007  Bhathena SJ, et al, Dietary flaxseed meal is more protective than soy protein concentrate against hypertriglyceridemia and steatosis of the liver in an animal model of obesity. J Am Coll Nutr. 2003 Apr;22(2):157-64.  Velasquez MT, et al, Dietary flaxseed meal reduces proteinuria and ameliorates nephropathy in an animal model of type II diabetes mellitus. Kidney Int. 2003 Dec;64(6):2100-7.
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