Effect of Dietary Polyunsaturated Fatty Acids on Tissue Vitamin E Status

Abstract

The purpose of this study was (1) to determine if feeding increasing dietary levels of polyunsaturated fatty acids (PUFA) over the relatively long period of 2 months affects the tissue content of α-tocopherol, and (2) to determine how increasing the intake of dietary PUFA changes the tissue ratio of α-tocopherol:PUFA. Weanling rats were fed a purified diet with 16% fat composed of a mixture of stripped lard and stripped corn oil to give three levels of linoleic acid ranging from 2% to 9% of the diet. α-Tocopherol was kept at a constant dietary level, 30 to 50 mg/kg in different experiments. After 8 to 10 weeks, tissues were analyzed for α-tocopherol and total PUFA. There was a tendency for plasma α-tocopherol to decrease with increasing dietary PUFA but in only one experiment was the change significant. Liver, muscle and adipose tissue showed no change in α-tocopherol in one experiment and a slight decrease in a second experiment. α-Tocopherol in heart and lung did not change in the first two experiments but decreased a maximum of 23% in two later experiments. Tissue PUFA increased as dietary PUFA increased. The ratio of α-tocopherol: PUFA in several tissues declined more with the first increase in dietary PUFA than with the second increase. Adipos tissue had the largest decrease in this ratio and heart and lung the smallest decrease. It is concluded that dietary PUFA has a variable but small effect in lowering the tissue content of α-tocopherol, and that the change in vitamin E status as judged by the tissue ratio of α-tocopherol:PUFA is primarily a result of increased tissue deposition of PUFA.