Ratios of polyunsaturated fatty acids to α‐tocopherol in tissues of rats fed corn or soybean oils

This study was part of a larger experiment designed to assess the vitamin E adequacy of corn and soybean oils in relation to their polyunsaturated fatty acids (PUFA). Young male rats were fed a semipurified diet containing 20% corn or soybean oil and adequate selenium. After 8 and 12 weeks, animals were sacrificed, and 7 tissues analyzed for α‐ and γ‐tocopherols and for fatty acids. Calculations were made of the molar ratios of total polyunsaturated fatty acids/α‐tocopherol, and also of all polyunsaturated fatty acids, except linoleate, designated polyunsaturated fatty acids>18∶2, to α‐tocopherol. It is proposed that the latter ratio may have more significance, physiologically, than when linoleic acid also is considered. Tissues from rats fed corn oil had slightly more favorable (lower) ratios than did tissues from rats fed soybean oil. In both groups, the molar polyunsaturated fatty acids>18∶2/α‐tocopherol ratio was lowest for heart and lung, intermediate for muscle and testis, and highest for liver, kidney, and adipose tissue. Since both corn and soybean oils provide adequate vitamin E as determined by several biochemical and physiological parameters, adequate molar ratios of polyunsaturated fatty acids>18∶2/α‐tocopherol were: lung, 400; heart and leg muscles, 700; testis, 1100; liver and kidney, 1500–2000; and adipose tissue, 2000.