Effects of soy protein supplemented with methionine on blood lipids and adiposity of rats.
OBJECTIVE
The effects of soy protein isolate (SPI) versus casein on blood lipids and adiposity were investigated in rats fed methionine-equivalent diets.


METHODS
Twenty-eight male Sprague-Dawley rats (230 to 250 g) were assigned in equal numbers to groups consuming SPI- or casein-based diets (20%) supplemented with L-methionine. After 28 d, blood was collected for triacylglycerol, total cholesterol, and high-density lipoprotein cholesterol assessment and epididymal fat pads were weighed.


RESULTS
Food intake (519 +/- 90 versus 490 +/- 115 g), weight gain (144 +/- 35 versus 133 +/- 28 g), food efficiency ratio (0.29 +/- 0.09 versus 0.28 +/- 0.06), epididymal fat pad weights (5.409 +/- 2.076 versus 4.768 +/- 1.867 g), and serum concentrations of triacylglycerol (96.3 +/- 41.8 versus 93.4 +/- 37.4 mg/dL) and high-density lipoprotein cholesterol (32.6 +/- 7.4 versus 33.8 +/- 4.4 mg/dL) were similar between the casein and SPI groups, respectively. However, total cholesterol (73.8 +/- 17.8 versus 59.3 +/- 11.9 mg/dL) concentration was higher for the casein-fed rats than for the SPI-fed rats, respectively (P < 0.05).


CONCLUSIONS
These results suggest that methionine supplementation may eliminate the decreased fat deposition previously ascribed to soy protein; however, methionine did not abolish the commonly observed hypocholesterolemic effects of soy.
Kern
Mark
M
Department of Exercise and Nutritional Sciences, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182-7251, USA. kern@mail.sdsu.edu
Ellison
Danielle
D
Marroquin
Yessenia
Y
Ambrose
Marie
M
Mosier
Kelly
K
D000273:Adipose Tissue; D000818:Animals; D001823:Body Composition; D002364:Caseins / Q000008:administration & dosage / Q000494:pharmacology; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D004044:Dietary Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D004435:Eating; D004822:Epididymis; D008055:Lipids / Q000097:blood*; D008297:Male; D008715:Methionine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D030262:Soybean Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D014280:Triglycerides / Q000097:blood; D015430:Weight Gain
D002364:Caseins; D008076:Cholesterol, HDL; D004044:Dietary Proteins; D008055:Lipids; D030262:Soybean Proteins; D014280:Triglycerides; D002784:Cholesterol; D008715:Methionine