天然维生素E的功效和作用是什么？

α-Tocopherol is a type of tocopherol or vitamin E. It has E number "E307".α-Tocopherol is a form of vitamin E that is preferentially absorbed and accumulated in humans. The measurement of "vitamin E" activity in international units (IU) was based on fertility enhancement by the prevention of spontaneous abortions in pregnant rats relative to alpha-tocopherol.There are three stereocenters in alpha-tocopherol, so this is a chiral molecule. The eight stereoisomers of alpha-tocopherol differ in the arrangement of groups around these stereocenters. In the image of RRR-alpha-tocopherol, all three stereocenters are in the R form. However, if the middle of the three stereocenters were changed (so the hydrogen was now pointing down and the methyl group pointing up), this would become the structure of RSR-alpha-tocopherol. RSR-alpha-tocopherol and RRR-alpha-tocopherol are diastereomers of each other. These stereoisomers can also be named in an alternative older nomenclature, where the stereocenters are either in the d or l form.1 IU of tocopherol is defined as ~ milligrams of RRR-alpha-tocopherol (formerly named d-alpha-tocopherol or sometimes ddd-alpha-tocopherol). 1 IU is also defined as 1 milligram of an equal mix of the eight stereoisomers, which is a racemic mixture called all-rac-alpha-tocopheryl acetate. This mix of stereoisomers is often called dl-alpha-tocopheryl acetate, even though it is more precisely dl,dl,dl-alpha-tocopheryl acetate). However, 1 IU of this racemic mixture is not now considered equivalent to 1 IU of natural (RRR) α-tocopherol, and the Institute of Medicine and the USDA now convert IU's of the racemic mixture to milligrams of equivalent RRR using 1 IU racemic mixture = 0.45 "milligrams α-tocopherol".天然维生素E在具有以下功能的保健食品中使用过该原料（注：不代表该原料本身具有以下保健功能）,具有如下功能:
增强免疫力,辅助降血脂,祛黄褐斑,缓解体力疲劳,抗氧化,辅助改善记忆,改善皮肤水份,通便,缓解视疲劳,提高缺氧耐受力,对化学性肝损伤有辅助保护功能,增加骨密度,对辐射危害有辅助保护功能,辅助降血糖,改善营养性贫血,改善睡眠,减肥,祛痤疮,改善生长发育,辅助降血压,其中在源海素牌维生素E软胶囊,宝健牌多种维生素矿物质片,康富森牌多种维生素硒软胶囊,中就有使用过该原料.
说明：以上对于原料功效的说明仅来源于其在对应保健食品中的运用，不代表该原料本身具有以下保健功能。