VITAMIN E

• Fat-soluble antioxidant

• Resides mostly in cell membranes

• An antioxidant can form a barrier between a target molecule (an unsaturated fatty acid in a cell membrane) and a compound seeking its electrons

• The antioxidant donates electrons or hydrogens to the electron-seeking compound

• This protects other molecules or parts of a cell from having electrons stolen

• If vitamin E is not available to do its job, electron-seeking compound-known as a free radial- can pull electrons from cell membranes, DNA, and other electron-dense cell components

• This either alters the cell’s DNA, which may increase the risk for cancer, or injures cell membranes, possibly causing the cell to die

• This free-radical production is a normal result of cell metabolism and immune system function

• For example, white blood cells generate free radicals as part of their action to stop infection

• The body needs antioxidants like vitamin E to carefully regulate this exposure to avoid related undesirable effects

• Experts do not know whether megadose vitamin E supplements taken by otherwise healthy people confer any additional protection against cardiovascular disease and cancer than that achieved by improving diet (especially fruit, vegetable, and whole-grain bread and cereal intake)

• Deficiency of vitamin E causes cell membranes to break down

• When oxidative damage causes the cell membranes of red blood ells to break, it is called hemolysis

VITAMIN E SOURCES AND NEEDS

• Major sources of vitamin E include plant oils, ready-to-eat breakfast cereals, some fruits and vegetables (asparagus, tomatoes, and green leafy vegetables) eggs, whole grains, nuts, and seeds

• Plant oils are made up of mainly unsaturated fatty acids, and the vitamin E in plant oils protects these unsaturated fats from oxidation

• animal fats and fish oils have practically no vitamin E

• cell damage by free radicals occurs over an extended period of time

• beneficial effects of vitamin E and other antioxidants in counteracting this damage is most apparent when viewed over the long term

Category: Biochemistry Notes