DIETARY BETA-IONONE SUPPRESSES HEPATIC 3-HYDROXY-3-METHYLGLUTARYL COENZYME-A REDUCTASE-ACTIVITY

Incorporation of apolar extracts of alfalfa into the diets of chickens effected. significant reductions in hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and serum concentrations of cholesterol (total and LDL) and apolipoprotein B. One of several mevalonate-suppressive constituents of the extracts shared characteristics with beta-ionone. Dietary beta-ionone, a potent inhibitor of hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase activity, was most effective under conditions favoring basal rather than induced reductase activity. This inhibitory action is distinct from that of mevinolin, a competitive inhibitor of reductase activity. The presence of beta-ionone in mills was confirmed. This demonstration of the cholesterol-suppressive action of a passive rather than a physiological constituent of milk may explain the conflicting reports of the impact of dairy products on blood cholesterol levels.