Xz. Zhang et Ac. Beynen, LOWERING EFFECT OF DIETARY MILK-WHEY PROTEIN V CASEIN ON PLASMA AND LIVER CHOLESTEROL CONCENTRATIONS IN RATS, British Journal of Nutrition, 70(1), 1993, pp. 139-146
The effect of dietary whey protein v. casein on plasma and liver chole
sterol concentrations was investigated in female, weanling rats. Balan
ced, purified diets containing either whey protein or casein, or the a
mino acid mixtures simulating these proteins, were used. The high-chol
esterol diets (10 g cholesterol/kg feed) had either 150 or 300 g prote
in or amino acids/kg feed. The diets were fed for 3 weeks. At the low
dietary protein level, whey protein v. casein did not affect plasma to
tal cholesterol, but lowered the concentration of liver cholesterol. A
t the high dietary protein level, whey protein significantly lowered p
lasma and liver cholesterol and also plasma triacylglycerols. The hypo
cholesterolaemic effect of whey protein was associated with a decrease
in very-low-density-lipoprotein cholesterol. At the high dietary prot
ein concentration, whey protein reduced the faecal excretion of bile a
cids when compared with casein. The effects of intact whey protein v.
casein were not reproduced by the amino acid mixtures simulating these
proteins. It is suggested tentatively that the cholesterol-lowering e
ffect of whey protein in rats is caused by inhibition of hepatic chole
sterol synthesis.