No conclusion could be made from this trial about whether supplemental vitamin E has the same effect, however (BBC 2005).
Vitamin E is widely used in industry as an inexpensive antioxidant (namely for cosmetics and foods).
Many naturopathic and orthomolecular medicine advocates suggest that vitamin E supplements contain at least 20 percent by weight of the other natural vitamin E isomers.
The structure natural a-tocopherol, the most potent natural source of vitamin E activity, was elucidated shortly thereafter, in 1938 (Fernholz 1938).
The methodology, interpretation and reporting of conventional vitamin E studies have even become contentious within conventional medicine circles (Carter 2005).
Vitamin E containing products are commonly used in the belief that vitamin E is good for the skin; many cosmetics include it, often labeled as tocopherol acetate, tocopheryl linoleate, or tocopheryl nicotinate.
Later studies saw no difference between the rate of absorption of these forms of vitamin E and found that tocopheryl esters and free tocopherol had the same bioavailability (Cheeseman et al.
The most sensitive membranes to toxic oxygen appear to the the membranes of nerves and thus vitamin E deficiency damages the nervous system (Brody 2004).
The terms vitamin E and tocopherol are sometimes used interchangeably but they are not synonymous.
Conventional medical studies on vitamin E, as of 2006 and as below, use either a synthetic all-racemic ("d, l-") alpha tocopheryl ester (acetate or succinate) or a semi-synthetic d-alpha tocopheryl ester (acetate or succinate).
Vitamin E deficiency causes neurological problems due to poor nerve conduction.
The researchers suggested that it is unlikely that the vitamin E supplement provided any protection against cardiovascular disease in the HOPE study.
Synthetic vitamin E derived from petroleum products is manufactured as all-racemic alpha tocopheryl acetate with a mixture of eight stereoisomers.
There has been research that suggests vitamin E alone does not attenuate the development or progression of AMD (Taylor et al.
Vitamin E is a term that applies to a set of related tocopherols and tocotrienols.
Some evidence associates higher intake of vitamin E with a decreased incidence of prostate cancer and breast cancer.
Vitamin E is the generic descriptor for any of a group of several related fat-soluble organic compounds, tocopherols and tocotrienols, that act as vitamins with antioxidant properties.
Other sources of vitamin E are whole grains, fish, peanut butter, goats milk, and green leafy vegetables.
Vitamin E deficiency is very rare but can strike people with diseases that prevent absorption of dietary fats and fat soluble nutrients (Brody 2004).
The 90-minute Bob Hope Christmas Specials were broadcast every holiday season until 1972.
An initial study in humans saw large variability between different people's absorption of all these forms of vitamin E, with no statistically-significant differences seen between tocopheryl esters and the free tocopherol (Horwitt et al.
Antioxidants such as vitamin E help protect against the damaging effects of free radicals, which may contribute to the development of chronic diseases such as cancer.
During feeding experiments with rats Herbert McLean Evans concluded, in 1922, that besides vitamins B and C, an unknown vitamin existed (Evans and Bishop 1922).
Vitamin E exists in eight different forms, four tocopherols and four tocotrienols.
Individuals with moderate to high intakes of dietary vitamin E were found to have a lower risk of Parkinson's.
One IU of vitamin E is the biological equivalent of about 0.667 milligrams (2/3 milligrams exactly) of RRR-alpha-tocopherol (formerly named d-alpha-tocopherol or sometimes ddd-alpha-tocopherol).
Tocotrienols, with four d- isomers, although less commonly known, also belong to the vitamin E family.
Vitamin E also may block the formation of nitrosamines, which are carcinogens formed in the stomach from nitrites consumed in the diet.
Preliminary research has led to a widely held belief that vitamin E may help prevent or delay coronary heart disease, but larger controlled studies have not confirmed such a benefit (Sesso et al.
Vitamin E also is proposed to help prevent the formation of blood clots, which could lead to a heart attack.
To date, human trials and surveys that have tried to associate vitamin E with incidence of cancer remain generally inconclusive.
Due to this contradictory and confusing evidence, vitamin E or tocopherol supplements are not currently recommended for treating or preventing Alzheimer's disease (Boothby and Doering 2005).
Alpha-tocopherol is the form of vitamin E that is preferentially absorbed and accumulated in humans (Rigotti 2007).
The term vitamin E should be used as the generic descriptor for all tocol and tocotrienol derivatives exhibiting qualitatively the biological activity of ?-tocopherol.
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.
Vitamin E appears to serve the body by protecting membranes from toxic oxygen damage.
Most studies about vitamin E have supplemented using only the synthetic alpha-tocopherol, but doing so leads to reduced serum gamma- and delta-tocopherol concentrations.
Some studies correlate additional cofactors, such as specific vitamin E isomers, for example, gamma-tocopherol and other nutrients such as selenium, with dramatic risk reductions in prostate cancer (Helzlsouer et al.
Other health benefits of vitamin E have been proposed, such as helping to combat heart disease, protect against certain cancers, and promote skin health, with diverse research findings.
The DRI for vitamin E is based on the alpha-tocopherol form because it is the most active form as originally tested.
Observational studies have associated lower rates of heart disease with higher vitamin E intake.
A study of endocrine systems revealed that female hippopotamuses may begin puberty as early as 3 or 4 years of age.
There has been speculation that vitamin E coupled with selenium may reduce the risk of prostate cancer (ACS 2008) by 30 percent (NCI 2008a).
Fortified breakfast cereals are also an important source of vitamin E in the United States.
Other trials have tested if giving vitamin E supplements reduce the risk of Parkinson's disease, or if they can slow the progression of the disease.
The IOM states that most North American adults get enough vitamin E from their normal diets to meet current recommendations.
Similarly, a trial using vitamin E alone found that vitamin E supplementation produced no change in the risk of developing cataracts or the rate of progression of existing cataracts (McNeil et al.