Vitamin E.
The term vitamin E is used to describe eight lipophilic, naturally occurring compounds that include four tocopherols and four tocotrienols designated as alpha-, beta-, gamma-, and delta-. The most well-known function of vitamin E is that of a chain-breaking antioxidant that prevents the cyclic propagation of lipid peroxidation. Despite its antioxidant function, dietary vitamin E requirements in humans are limited only to alpha-tocopherol because the other forms of vitamin E are poorly recognized by the hepatic alpha-tocopherol transfer protein (TTP), and they are not converted to alpha-tocopherol by humans. In attempts to gain a better understanding of vitamin E's health benefits, the molecular regulatory mechanisms of vitamin E have received increased attention. Examples of these mechanisms include: (1) the role of the hepatic alpha-TTP in preferentially secreting alpha-tocopherol into the plasma, (2) phase I and phase II metabolism of vitamin E and the potential impact for drug-vitamin E interactions, and (3) the regulation of biliary excretion of vitamin E by ATP-binding cassette protein(s). It is expected that the continued studies of these regulatory pathways will provide new insights into vitamin E function from which additional human health benefits will evolve.
Mustacich
Debbie J
DJ
Linus Pauling Institute, Oregon State University, Corvallis, Oregon 97331, USA.
Bruno
Richard S
RS
Traber
Maret G
MG
D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D001692:Biological Transport; D002914:Chylomicrons / Q000378:metabolism; D006801:Humans; D051381:Rats; D014810:Vitamin E / Q000737:chemistry / Q000378:metabolism / Q000502:physiology
D000975:Antioxidants; D002914:Chylomicrons; D014810:Vitamin E