Graded dietary levels of RRR-g-tocopherol induce a marked increase in the concentrations of a- and g-tocopherol in nervous tissues, heart, liver and muscle of vitamin-E-deficient rats

The effect of dietary RRR-g-tocopherol supplementation on serum and tissue aand g-tocopherol concentrations was studied in vitamin-E-deficient rats fed diets containing adequate levels of RRR-a-tocopherol and graded levels of RRR-g-tocopherol over a 60 day period. Feeding rats with a RRR-a-tocopherol-supplemented diet induced in forebrain, sciatic endoneurium, skeletal muscle, heart and liver a marked increase in a-tocopherol concentration. In contrast, feeding rats with a diet containing the same level of RRR-g-tocopherol induced a small increase in g-tocopherol concentrations in brain, sciatic endoneurium, skeletal, muscle, heart and liver and a slight but significant decrease in a-tocopherol concentration in all tissues examined. In rats fed diets containing a constant level of RRR-a-tocopherol and graded levels of RRR-g-tocopherol, the concentrations of a-tocopherol in all tissues were much higher than those in rats fed a control diet containing RRR-a-tocopherol alone. The higher the gra ratio, the more the a-tocopherol concentrations increased. Significant positive linear regressions were found between the gra ratio and the aand g-tocopherol concentrations in most of the tissues examined. These results indicate that when g-tocopherol was supplied continuously in the diet g-tocopherol accumulated significantly in the tissues but to a much smaller extent than when rats were fed with RRR-a-tocopherol. These experiments also indicate that g-tocopherol did not depress the serum and tissue a-tocopherol concentrations. On the contrary, g-tocopherol supplements induced a marked increase in a-tocopherol concentrations in the serum and tissues. These results suggest that there is a relationship between aand g-tocopherol levels in vivo and that the biopotency of a-tocopherol should be reevaluated especially when high levels of g-tocopherol were present in the diet.