Cereal grains, alpha tocotrienol and cholesterol metabolism in the rat

The influence of alpha (α)-tocotrienol, the main vitamer of vitamin E in barley and oats, on cholesterol synthesis has been studied in laboratory rats. Both oats and barley lowered plasma cholesterol relative lo wheat, which had no such effect, and the change has been attributed to an inhibitory influence of a -tocotrienol on cholesterol synthesis rate. Vitamin E was stripped from oats and barley by a petroleum ether extraction procedure and the grains compared with their unstripped equivalents. In the oats feeding experiment this resulted in a higher plasma cholesterol and lower liver cholesterol synthesis rate. The barley experiment produced no significant response. Pure α-tocotrienol was gavaged into rats fed a semipurified diet without vitamin E, at the rate of 380 μg/rat/day for 28 days. There was no significant influence on plasma cholesterol level or on liver cholesterol synthesis rate. From these studies it is concluded that a -tocotrienol does not influence cholesterol synthesis rate significantly. Therefore, it is unlikely lo be a factor in oats and barley responsible for the plasma cholesterol lowering observed.