The Fat Antioxidant
The main form of vitamin E is alpha-tocopherol. Tocopherols were discovered at the University of California at Berkeley in 1922, where they were found to be essential to maintain fertility. Pure alpha-tocopherol was first isolated from wheatgerm oil in 1936. The word tocopherol means “to bear offspring” and derives from the Greek root phero, which means “to bring forth,” and the Greek root tos, which means “childbirth.” Tocopherols are a family of eight fat-soluble alcohols. The final “ol” in the name tocopherol indicates that it is an alcohol.
Forms of Vitamin E
The tocopherols are divided into four types: alpha-tocopherol, beta-tocopherol, gamma-tocopherol, and delta-tocopherol, as shown in Figure 5-1. Also in the vitamin E family are the very similar tocotrienols. These tocotrienols are also divided into four groups: alpha-, beta-, gamma-, and delta-tocotrienol. All tocopherols and
Figure 5-1 Tocopherol structures.
all tocotrienols have the ability to donate a hydrogen atom to neutralize free radicals. They also have a side chain with the ability to penetrate biological membranesand fats.
TOCOTRIENOLS
Tocotrienols are much more potent antioxidants than tocopherols. They are very similar to tocopherols, as seen in Figure 5-2. Unfortunately, they are poorly assimilated and rapidly eliminated from the body. The tocotrienols are well-absorbed by skin, so they are good choices for antioxidants in lotions. Vitamin E is sometimes used to reduce scarring from healing injuries after the skin has closed. The tocotrienol form of vitamin E may be the correct choice for this type of topical application. Palm oil is a rich source of tocotrienols.
Figure 5-2 Tocopherols and tocotrienols.
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The main form of vitamin E is alpha-tocopherol. Tocopherols were discovered at the University of California at Berkeley in 1922, where they were found to be essential to maintain fertility. Pure alpha-tocopherol was first isolated from wheatgerm oil in 1936. The word tocopherol means “to bear offspring” and derives from the Greek root phero, which means “to bring forth,” and the Greek root tos, which means “childbirth.” Tocopherols are a family of eight fat-soluble alcohols. The final “ol” in the name tocopherol indicates that it is an alcohol.
Forms of Vitamin E
The tocopherols are divided into four types: alpha-tocopherol, beta-tocopherol, gamma-tocopherol, and delta-tocopherol, as shown in Figure 5-1. Also in the vitamin E family are the very similar tocotrienols. These tocotrienols are also divided into four groups: alpha-, beta-, gamma-, and delta-tocotrienol. All tocopherols and
Figure 5-1 Tocopherol structures.
all tocotrienols have the ability to donate a hydrogen atom to neutralize free radicals. They also have a side chain with the ability to penetrate biological membranesand fats.
ALPHA-TOCOPHEROL
Alpha-tocopherol is the form of vitamin E found in the largest quantities in blood and tissue inside the human body. Alpha-tocopherol is a powerful antioxidant that protects membranes and low density lipoproteins (LDL) from free radical damage. Alpha-tocopherol is the only form of vitamin E that the human body actively works to keep in the bloodstream. The RDAs for vitamin E are based upon levels of alpha-tocopherol.GAMMA-TOCOPHEROL
Gamma-tocopherol is the type of vitamin E found in the greatest abundance in most American diets. Blood levels of gamma-tocopherol are typically only 10 percent of the blood levels of alpha-tocopherol, despite the larger dietary intake of gamma-tocopherol. On the other hand, certain tissues do have significant concentrations of gamma-tocopherol. Gamma-tocopherol makes up about 40 percent of the tocopherols in muscles and about a third of the tocopherols in veins. More research is needed to confirm if gamma-tocopherol is effective in reducing the risk of prostate cancer. Gamma-tocopherol may be more potent than alpha-tocopherol as an anticoagulant.MIXED TOCOPHEROLS
There is general agreement that increased levels of vitamin E in the diet reduce the risk of cardiovascular disease. However, studies on the cardiovascular protective effects of supplementary vitamin E given as synthetic alpha-tocopherol have had inconsistent results. Research continues, but there are indications that the other forms of tocopherols, collectively called mixed tocopherols, are also important as antioxidants and anticoagulants.TOCOTRIENOLS
Tocotrienols are much more potent antioxidants than tocopherols. They are very similar to tocopherols, as seen in Figure 5-2. Unfortunately, they are poorly assimilated and rapidly eliminated from the body. The tocotrienols are well-absorbed by skin, so they are good choices for antioxidants in lotions. Vitamin E is sometimes used to reduce scarring from healing injuries after the skin has closed. The tocotrienol form of vitamin E may be the correct choice for this type of topical application. Palm oil is a rich source of tocotrienols.
Figure 5-2 Tocopherols and tocotrienols.
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