Abstract
Radish and spinach leaf protein isolates (RLP and SLP, respectively) were prepared from chilled aqueous 0.2% sodium hydroxide extract of their leaves. The RLP and SLP, and those supplemented with methionine (RLP + Met and SLP + Met, respectively) to become equal to casein in methionine content, were compared with casein for their effects on serum cholesterol level in rats fed with a cholesterol-enriched diet for 14 days. Each protein isolate was incorporated into the cholesterol-enriched diet to provide a 15% protein level. RLP was extremely inferior to SLP and casein for body weight gain of rats, but that of rats fed with RLP + Met diet was almost equal to that of casein and SLP groups. The serum cholesterol level in rats fed with SLP and SLP + Met diets was significantly lower as compared with that of the casein-fed rats. Both the amounts of excreted cholesterol and bile acids were significantly higher in rats fed with the SLP and SLP + Met diets than that of the casein-fed rats. These results suggest that the hypocholesterolemic action of SLP may in part have been due to the inhibition of intestinal absorption of both cholesterol and bile acids. RLP + Met diet tended to decrease the serum cholesterol level as compared to casein diet, but the difference was not significant.
