"Vitamin E" is a term used to collectively describe a group of eight different antioxidant vitamins. Four of these are tocopherols; the other four are tocotrienols. Though the Linus Pauling Institute has dismissed tocotrienols as nutritionally insignificant, Tong Wang, associate professor of Food Science and Human Nutrition at Iowa State University, counters that tocotrienols have significant biological functions that warrant further study.
Vitamin E
University of California researchers discovered vitamin E in 1922. It is an essential, fat-soluble antioxidant that supports fertility, thus it was initially named tocopherol, a term derived from Greek words referring to childbirth. Since that time, other compounds called tocotrienols were also found to have vitamin E activity. Organisms that are capable of photosynthesis create vitamin E, but it can also be chemically synthesized in laboratories.
Structural Differences
The chemical structure of tocopherol was first determined in 1938, the same year that tocopherol was synthesized in a laboratory. Today, "vitamin E" is a term that describes all tocopherols and substances derived from them that have the same biological activity as RRR-α-tocopherol. Tocotrienols fall within this description but differ from tocopherols in that they have a series of three double bonds within their molecular structure that are not found in tocopherols.
Functional Differences
Vitamin E is primarily known as an antioxidant. Antioxidants are nutrients that neutralize unstable molecules called free radicals that cause cell damage. Free radical damage has been linked to numerous health disorders such as heart disease and cancer. Additionally, tocopherols have demonstrated the ability to decrease the formation of blood clots and reduce inflammation.
Tocotrienols have effects not associated with tocopherols, according to Wang. They exert a protective influence over the nervous system, fight cancer and lower cholesterol in ways that tocopherols do not. Though tocotrienols are higher in antioxidant activity than tocopherols, tocopherols are more readily absorbed and utilized by the human body, according to "The Journal of Nutrition."
Different Sources
Though all forms of vitamin E are derived from organisms that undergo photosynthesis, tocopherols are far more readily abundant than tocotrienols. Tocopherols are readily found in plant tissues such as leaves and seeds. Tocotrienols are not typically present in plant vegetative tissue, according to "Life Sciences"; they are primarily found in seeds such as wheat, rice and barley.
References
- Tocopherols and Tocotrienols - Structure and Function; Tong Wang
- "The Journal of Nutrition"; Molecular Aspects of α-Tocotrienol Antioxidant Action and Cell Signalling; Lester Packer, et al.; 2001
- "Life Sciences"; Tocotrienols: Vitamin E Beyond Tocopherols; Chandan K. Sen, et al.; March 2006
- Linus Pauling Institute at Oregon State University; Vitamin E; Jane Higdon; November 2004
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