Cholesterol lowering effect of sulfur-containing amino acids added to a soybean protein diet in rats.
The cholesterol-lowering action of soybean protein was studied with rats from the aspect of sulfur-containing amino acids using casein as a counterpart. Weanling rats were fed for 3 wk on a soybean protein isolate (SPI) or casein diet. Serum cholesterol levels did not differ between the two diet groups, but were lowered by supplementing methionine to a 10% SPI diet or cystine to an amino acid mixture diet, equivalent to a 10% SPI or to a 20% SPI diet. By adding methionine or cystine to a 10% SPI diet, cholesterol 7alpha-hydroxylase activity was elevated concomitantly with elevated hepatic glutathione (GSH) level, while hydroxyl methyl-glutalyl coenzyme A reductase activity was reduced by methionine, regardless of GSH levels. Excretion of fecal steroid was not significantly changed by addition of either amino acid, as expressed per body weight. These results indicate that the relative amount of methionine and cystine in a diet affected cholesterol metabolizing enzyme activity in a way not parallel to GSH concentration.
Taniguchi
Misako
M
Department of Nutrition Sciences, Nakamura Gakuen University, Fukuoka, Japan. tanim@nakamura-u.ac.jp
Nagao
Koji
K
Inoue
Keiko
K
Imaizumi
Katsumi
K
D000214:Acyl Coenzyme A / Q000378:metabolism; D000818:Animals; D000924:Anticholesteremic Agents / Q000494:pharmacology*; D001835:Body Weight; D002364:Caseins / Q000494:pharmacology; D002784:Cholesterol / Q000378:metabolism*; D002790:Cholesterol 7-alpha-Hydroxylase / Q000378:metabolism; D003545:Cysteine / Q000494:pharmacology*; D019587:Dietary Supplements; D002149:Energy Intake; D005243:Feces / Q000737:chemistry; D005978:Glutathione / Q000378:metabolism*; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008715:Methionine / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D030262:Soybean Proteins / Q000494:pharmacology*; D013025:Glycine max
D000214:Acyl Coenzyme A; D000924:Anticholesteremic Agents; D002364:Caseins; D030262:Soybean Proteins; C008047:3-hydroxy-3-methylglutaryl-coenzyme A; D002784:Cholesterol; D008715:Methionine; D002790:Cholesterol 7-alpha-Hydroxylase; D005978:Glutathione; D003545:Cysteine