Lettuce, tocopherol

Vitamin E (a-tocopherol) occurs naturally in most vegetable oils. The highest concentrations are found in corn, soybean oils, sunflower seed, wheat germ, rapeseed, alfalfa, and lettuce. It is claimed to have age-retardant properties. May produce erythema-multiforme-like eruptions... 

Cho EA, Lee CA, Kim YS, Baek SH, De Los Reyes B, Yun SJ (2005) Expression of y-tocopherol methyltransferase transgene improves tocopherol composition in lettuce (Lactuca sativa L.). Molecules Cells 19 16-22... 

Stamler (1956) described a diet which causes a toxemia of pregnancy in rats. The effect disappeared when com oil was given instead of cod liver oil. Crude linoleic acid was approximately as effective. The eclamptic disease could be prevented by prior treatment of the test animals with vitamin E (a-tocopherol) or lettuce or by adding these substances to the toxic diet. 

The cod liver oil proved to be the critical component of the diet. Substitution by com oil made the diet nontoxic, and crude linoleic acid was approximately as effective. The eclamptic disease could be prevented by treating the animals with a-tocopherol or lettuce before the toxic diet was given, or by adding these materials to the eclamptogenic diet. Apart from a possible toxic effect of the vitamin D, it is also possible that the oil itself has a toxic effect. It is known that highly unsaturated acids are present which do not have the activity of the essential unsaturated fatty acids, because they have cis-trans and trans-trans configurations instead of the active cis-ds form. Even deficiency of the essential unsaturated fatty acids may be promoted. The crude linoleic acid, which was not quite as active as corn oil, may contain about 50% of the inactive cis-trans configura-tion(s). The vitamin E content of the com oil is probably important also. 

HISTORY. In 1922, Evans and Bishop, of the University of California, discovered that a fat-soluble dietary factor (then called factor X) in lettuce and wheat germ was essential for successful reproduction in rats. In 1924, Sure, of the University of Arkansas, named the factor vitamin E. In 1936, Evans and co-workers isolated crystalline vitamin E from wheat germ oil and named it tocopherol, from the Creek words tokos (offspring) and pherein (to bear), meaning to bear offspring. In 1938, the vitamin was first synthesized by the Swiss chemist, Karrer. 

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