| Tocopherol, or Vitamin E, is a
| |
| | Researchers are fairly certain that
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| fat-soluble vitamin in eight forms that
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| | oxidative modification of LDL-cholesterol
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| is an important antioxidant. Vitamin E is
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| | (sometimes called "bad" cholesterol)
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| often used in skin creams and lotions
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| | promotes blockages in coronary arteries
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| because it is believed to play a role in
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| | that may lead to atherosclerosis and
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| encouraging skin healing and reducing
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| | heart attacks. Vitamin E may help prevent
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| scarring after injuries such as burns.
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| | or delay coronary heart disease by
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| Natural vitamin E exists in eight
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| | limiting the oxidation of
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| different forms or isomers, four
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| | LDL-cholesterol. Vitamin E also may help
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| tocopherols and four tocotrienols. All
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| | prevent the formation of blood clots,
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| isomers have a chromanol ring, with a
| |
| | which could lead to a heart attack.
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| hydroxyl group which can donate a
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| | Observational studies have associated
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| hydrogen atom to reduce free radicals and
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| | lower rates of heart disease with higher
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| a hydrophobic side chain which allows for
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| | vitamin E intake. A study of
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| penetration into biological membranes.
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| | approximately 90,000 nurses suggested
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| There is an alpha, beta, gamma and delta
| |
| | that the incidence of heart disease was
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| form of both the tocopherols and
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| | 30% to 40% lower among nurses with the
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| tocotrienols, determined by the number of
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| | highest intake of vitamin E from diet and
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| methyl groups on the chromanol ring. Each
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| | supplements. The range of intakes from
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| form has its own biological activity, the
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| | both diet and supplements in this group
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| measure of potency or functional use in
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| | was 21.6 to 1,000 IU (32 to 1,500 mg),
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| the body.
| |
| | with the median intake being 208 IU (139
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| Sources of vitamin E In foods, the most
| |
| | mg). A 1994 review of 5,133 Finnish men
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| abundant sources of vitamin E are
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| | and women aged 30 - 69 years suggested
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| vegetable oils such as palm oil,
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| | that increased dietary intake of vitamin
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| sunflower, canola, corn, soybean and
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| | E was associated with decreased mortality
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| olive oil. Nuts, sunflower seeds,
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| | (death) from heart disease.
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| seabuckthorn berries, and wheat germ are
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| | But even though these observations are
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| also good sources. Other sources of
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| | promising, randomized clinical trials
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| vitamin E are whole grains, fish, peanut
| |
| | raise questions about the role of vitamin
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| butter, and green leafy vegetables.
| |
| | E supplements in heart disease. The Heart
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| Fortified breakfast cereals are also an
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| | Outcomes Prevention Evaluation (HOPE)
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| important source of vitamin E in the
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| | Study followed almost 10,000 patients for
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| United States. Although originally
| |
| | 4.5 years who were at high risk for heart
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| extracted from wheat germ oil, most
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| | attack or stroke. In this intervention
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| natural vitamin E supplements are now
| |
| | study the subjects who received 265 mg
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| derived from vegetable oils, usually
| |
| | (400) IU of vitamin E daily did not
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| soybean oil.
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| | experience significantly fewer
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| Forms of vitamin E Alpha-tocopherol is
| |
| | cardiovascular events or hospitalizations
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| traditionally recognized as the most
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| | for heart failure or chest pain when
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| active form of vitamin E in humans, and
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| | compared to those who received a sugar
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| is a powerful biological antioxidant. The
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| | pill. The researchers suggested that it
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| measurement of "vitamin E" activity in
| |
| | is unlikely that the vitamin E supplement
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| international units (IU) was based on
| |
| | provided any protection against
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| fertility enhancement by the prevention
| |
| | cardiovascular disease in the HOPE study.
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| of spontaneous abortions in pregnant rats
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| | This study is continuing, to determine
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| relative to alpha tocopherol. It
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| | whether a longer duration of intervention
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| increases naturally to about 150% of
| |
| | with vitamin E supplements will provide
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| normal in the maternal circulation during
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| | any protection against cardiovascular
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| human pregnancies. 1 IU of vitamin E is
| |
| | disease.
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| defined as the biological equivalent of
| |
| | Vitamin E and cancer Antioxidants such as
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| .667 milligrams of d-alpha-tocopherol, or
| |
| | vitamin E help protect against the
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| of 1 milligram of dl-alpha-tocopherol
| |
| | damaging effects of free radicals, which
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| acetate. The other isomers are slowly
| |
| | may contribute to the development of
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| being recognized as research begins to
| |
| | chronic diseases such as cancer. Vitamin
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| elucidate their additional roles in the
| |
| | E also may block the formation of
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| human body. Many naturopathic and
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| | nitrosamines, which are carcinogens
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| orthomolecular medicine advocates suggest
| |
| | formed in the stomach from nitrites
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| that vitamin E supplements contain at
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| | consumed in the diet. It also may protect
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| least 20% by weight of the other natural
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| | against the development of cancers by
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| vitamin E isomers. Commercially available
| |
| | enhancing immune function. To date, human
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| blends of natural vitamin E include
| |
| | trials and surveys that have tried to
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| "mixed tocopherols" and "high gamma
| |
| | associate vitamin E with incidence of
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| tocopherol" formulas. Also selenium,
| |
| | cancer remain generally inconclusive.
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| Coenzyme Q10, and ample vitamin C have
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| | Some evidence associates higher intake of
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| been shown to be essential cofactors of
| |
| | vitamin E with a decreased incidence of
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| natural tocopherols.
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| | prostate cancer and breast cancer.
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| Tocotrienols, with four d- isomers, also
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| | Some studies correlate additional
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| belong to the vitamin E family. The four
| |
| | cofactors, such as specific vitamin E
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| tocotrienols have structures
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| | isomers, e.g. gamma-tocopherol, and other
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| corresponding to the four tocopherols,
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| | nutrients, e.g. selenium, with dramatic
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| except with an unsaturated bond in each
| |
| | risk reductions in prostate cancer .
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| of the three isoprene units that form the
| |
| | However, an examination of the effect of
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| hydrocarbon tail. Tocopherols have a
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| | dietary factors, including vitamin E, on
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| saturated phytyl tail.
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| | incidence of postmenopausal breast cancer
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| Antioxidants such as vitamin E act to
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| | in over 18,000 women from New York State
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| protect cells against the effects of free
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| | did not associate a greater vitamin E
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| radicals, which are potentially damaging
| |
| | intake with a reduced risk of developing
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| by-products of the body's metabolism.
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| | breast cancer.
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| Free radicals can cause cell damage that
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| | A study of women in Iowa provided
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| may contribute to the development of
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| | evidence that an increased dietary intake
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| cardiovascular disease and cancer.
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| | of vitamin E may decrease the risk of
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| Vitamin C and other anti-oxidants recycle
| |
| | colon cancer, especially in women under
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| vitamin E end-products back into
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| | 65 years of age. On the other hand,
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| effective suppressors of free radicals.
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| | vitamin E intake was not statistically
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| Studies are underway to determine whether
| |
| | associated with risk of colon cancer in
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| vitamin E might help prevent or delay the
| |
| | almost 2,000 adults with cancer who were
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| development of those chronic diseases.
| |
| | compared to controls without cancer. At
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| Commercial vitamin E supplements can be
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| | this time there is limited evidence to
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| classified into several distinct
| |
| | recommend vitamin E supplements for the
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| categories: fully synthetic vitamin E,
| |
| | prevention of cancer.
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| "d,l-alpha-tocopherol", the most
| |
| | Recent studies also show that vitamin E
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| inexpensive, most commonly sold
| |
| | acts as an effective free radical
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| supplement form usually as the acetate
| |
| | scavenger and can lower the incidence of
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| ester; semisynthetic "natural source"
| |
| | lung cancer in smokers. The effects are
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| vitamin E esters, the "natural source"
| |
| | opposite to that of the clinical trials
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| forms used in tablets and multiple
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| | based on administering carotenoid to male
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| vitamins; highly fractionated natural
| |
| | smokers, that resulted in increased risk
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| d-alpha tocopherol; less fractionated
| |
| | of lung cancer. Hence vitamin E is an
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| "natural mixed tocopherols"; high
| |
| | effective antagonist to the oxidative
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| gamma-tocopherol fraction supplements;
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| | stress that is imposed by high
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| and tocotrienol supplements.
| |
| | carotenoids in certain patients.
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| Synthetic vitamin E, usually marked as
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| | Vitamin E and cataracts A cataract is a
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| d,l-tocopherol or d,l tocopheryl acetate,
| |
| | condition of clouding of the tissue of
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| with 50% d-alpha tocopherol moiety and
| |
| | the lens of the eye. They increase the
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| 50% l-alpha-tocopherol moiety, as
| |
| | risk of disability and blindness in aging
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| synthesized by an earlier process is now
| |
| | adults. Antioxidants are being studied to
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| actually manufactured as all-racemic
| |
| | determine whether they can help prevent
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| alpha tocopherol, with only about one
| |
| | or delay cataract growth. Observational
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| alpha tocopherol molecule in 8 molecules
| |
| | studies have found that lens clarity,
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| as actual d-alpha tocpherol. The
| |
| | which is used to diagnose cataracts, was
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| synthetic form is not as active as the
| |
| | better in regular users of vitamin E
|
| natural alpha tocopherol form. The 1950's
| |
| | supplements and in persons with higher
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| thalidomide disaster with numerous severe
| |
| | blood levels of vitamin E. A study of
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| birth defects is a common example of d-
| |
| | middle aged male smokers, however, did
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| vs l- epimer forms type problem with
| |
| | not demonstrate any effect from vitamin E
|
| synthesized racemic mixtures.
| |
| | supplements on the incidence of cataract
|
| Information on any side effects of the
| |
| | formation. The effects of smoking, a
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| synthetic vitamin E epimers is not
| |
| | major risk factor for developing
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| readily available. Naturopathic and
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| | cataracts, may have overridden any
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| orthomolecular medicine advocates have
| |
| | potential benefit from the vitamin E, but
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| long considered the synthetic vitamin E
| |
| | the conflicting results also indicate a
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| forms to be with little or no merit for
| |
| | need for further studies before
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| cancer, circulatory and heart diseases.
| |
| | researchers can confidently recommend
|
| Semisynthetic "natural source" vitamin E,
| |
| | extra vitamin E for the prevention of
|
| manufacturers convert the common natural
| |
| | cataracts. It is important to note that
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| beta, gamma and delta tocopherol isomers
| |
| | the term "cataract" may be used in common
|
| into esters using acetic or succinic acid
| |
| | parlance for an opacity involving any
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| and add methyl groups to yield d-alpha
| |
| | tissue of the eye, for example a corneal
|
| tocopheryl esters such as d-alpha
| |
| | scar. Thus a character in theater or on
|
| tocopheryl acetate or d-alpha tocopheryl
| |
| | television who is blind from cataracts
|
| succinate. These tocopheryl esters are
| |
| | might have white instead of clear
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| more stable and are easy to use in
| |
| | corneas, covering over the iris and
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| tablets and multiple vitamin pills.
| |
| | pupil. Since the lens is behind the
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| Because only alpha tocopherols were
| |
| | pupil, real cataracts are difficult to
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| officially counted as "vitamin E" in
| |
| | see without special instrumentation, so
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| supplements, refiners and manufacturers
| |
| | people with cataracts have rather
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| faced enormous economic pressure to
| |
| | normally appearing eyes.
|
| esterify and methylate the other natural
| |
| | Vitamin E and Alzheimer's disease
|
| tocopherol isomers, d-beta-, d-gamma- and
| |
| | Alzheimer's disease is a wasting disease
|
| d-delta-tocopherol into d-alpha
| |
| | of the brain. An observational trial
|
| tocopheryl acetate or succinate.
| |
| | conducted by The Johns Hopkins University
|
| Tocopheryl nicotinate and tocopheryl
| |
| | Bloomberg School of Public Health found
|
| linolate esters are used in cosmetics and
| |
| | that when vitamin E is taken daily in
|
| some pharmaceuticals. In the healthy
| |
| | large doses (400-1000IU) in combination
|
| human body, the semisynthetic forms are
| |
| | with vitamin C (500-1000mg) the onset of
|
| easily de-esterified over several days,
| |
| | Alzheimer's was reduced between 64 and
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| primarily in the liver, but not for
| |
| | 78%.
|
| common problems in premature babies, aged
| |
| | Vitamin E and Parkinson's disease In May
|
| or ill patients.
| |
| | 2005, The Lancet Neurology published a
|
| Recommended amounts The U.S. Dietary
| |
| | study suggesting that vitamin E may help
|
| Reference Intake (DRI) Recommended Daily
| |
| | protect against Parkinson's disease.
|
| Amount (RDA) for a 25-year old male for
| |
| | Individuals with moderate to high intakes
|
| Vitamin E is 15 mg/ day. This is
| |
| | of dietary vitamin E were found to have a
|
| approximately 15 IU/day.
| |
| | lower risk of Parkinson's. No conclusion
|
| The DRI for vitamin E is based on the
| |
| | was drawn about whether supplemental
|
| alpha-tocopherol form because it is the
| |
| | vitamin E has the same effect, however.
|
| most active, or usable, form as
| |
| | Health risks of too much vitamin E The
|
| originally tested. Results of two
| |
| | health risk of too much vitamin E is
|
| national surveys, the National Health and
| |
| | disputed. A recent review of the safety
|
| Nutrition Examination Survey (NHANES III
| |
| | of vitamin E in the elderly indicated
|
| 1988-91) and the Continuing Survey of
| |
| | that taking vitamin E supplements for up
|
| Food Intakes of Individuals (1994 CSFII)
| |
| | to four months at doses of 530 mg or 800
|
| indicated that the dietary intake of most
| |
| | IU (35 times the current RDA) had no
|
| Americans does not provide the
| |
| | significant adverse effect on general
|
| recommended intake for vitamin E.
| |
| | health, body weight, levels of body
|
| However, a 2000 Institute of Medicine
| |
| | proteins, lipid levels, liver or kidney
|
| (IOM) report on vitamin E states that
| |
| | function, thyroid hormones, amount or
|
| intake estimates of vitamin E may be low
| |
| | kinds of blood cells, and bleeding time.
|
| because energy and fat intake is often
| |
| | Even though this study provides evidence
|
| underreported in national surveys and
| |
| | that taking a vitamin E supplement
|
| because the kind and amount of fat added
| |
| | containing 530 mg or 800 IU for four
|
| during cooking is often not known. The
| |
| | months is safe, the long term safety of
|
| IOM states that most North American
| |
| | vitamin E supplementation has not been
|
| adults get enough vitamin E from their
| |
| | authoritatively tested. However,
|
| normal diets to meet current
| |
| | "toxicity symptoms have not been reported
|
| recommendations. However, they do caution
| |
| | even at intakes of 800 IU per kilogram of
|
| individuals who consume low fat diets
| |
| | body weight daily for 5 months" according
|
| because vegetable oils are such a good
| |
| | to the Food and Nutrition Board
|
| dietary source of vitamin E. "Low-fat
| |
| | (Rosenberg, et al), an amount that
|
| diets can substantially decrease vitamin
| |
| | corresponds to 60,000 IU per day for a 75
|
| E intakes if food choices are not
| |
| | kg adult.
|
| carefully made to enhance
| |
| | The U.S. Institute of Medicine has set a
|
| alpha-tocopherol intakes". Vitamin E
| |
| | Dietary Reference Intake upper tolerable
|
| supplements are absorbed best when taken
| |
| | intake level for a 25-year old male for
|
| with meals. (Iuliano 2001) Factors in
| |
| | vitamin E at 1,000 mg (1,500 IU) for any
|
| vitamin E deficiency There are three
| |
| | form of supplementary alpha-tocopherol
|
| specific situations when a vitamin E
| |
| | per day because the nutrient can act as
|
| deficiency is likely to occur. It is seen
| |
| | an anticoagulant and increase the risk of
|
| in persons who cannot absorb dietary fat,
| |
| | bleeding problems. Upper tolerable intake
|
| has been found in premature, very low
| |
| | levels "represent the maximum intake of a
|
| birth weight infants (birth weights less
| |
| | nutrient that is likely to pose no risk
|
| than 1500 grams, or 3 1/2 pounds), and is
| |
| | of adverse health effects in almost all
|
| seen in individuals with rare disorders
| |
| | individuals in the general population".
|
| of fat metabolism. A vitamin E deficiency
| |
| | A 2004 metastudy at Johns Hopkins, loudly
|
| is usually characterized by neurological
| |
| | played in the media, questioned the
|
| problems due to poor (bad) nerve
| |
| | benefit of high dosage alpha tocopherol.
|
| conduction.
| |
| | Others have stated that many favorable
|
| Individuals who cannot absorb fat may
| |
| | reports were improperly excluded, that
|
| require a vitamin E supplement because
| |
| | one flawed study contributed the most
|
| some dietary fat is needed for the
| |
| | negative statistics, and have suggested
|
| absorption of vitamin E from the
| |
| | that several selection criteria
|
| gastrointestinal tract. Anyone diagnosed
| |
| | introduced significant bias with a
|
| with cystic fibrosis, individuals who
| |
| | resultant inaccurate statement. Of the 19
|
| have had part or all of their stomach
| |
| | studies utilized (of 36 originally), only
|
| removed, and individuals with
| |
| | one study clearly used a "natural source"
|
| malabsorptive problems such as Crohn's
| |
| | isomer, a d-alpha tocopheryl ester, (more
|
| disease may not absorb fat and should
| |
| | correctly: R,R,R-alpha tocopheryl since
|
| discuss the need for supplemental vitamin
| |
| | 1981) instead of the commonly used
|
| E with their physician (3). People who
| |
| | synthetic (all-racemic) alpha tocopheryl
|
| cannot absorb fat often pass greasy
| |
| | acetate composed from all 8 alpha
|
| stools or have chronic diarrhea.
| |
| | tocopherol epimers. The generalization of
|
| Very low birth weight infants may be
| |
| | results from all-racemic alpha-tocopheryl
|
| deficient in vitamin E. These infants are
| |
| | esters as "vitamin E" about the
|
| usually under the care of a
| |
| | performance of the natural d-alpha,
|
| neonatologist, a pediatrician
| |
| | d-beta, d-gamma and d-delta tocopherol
|
| specializing in the care of newborns, who
| |
| | alcohol isomers is overbroad and a
|
| evaluates and treats the exact
| |
| | frequent subreption in the literature.
|
| nutritional needs of premature infants.
| |
| | The Shute brothers, Canadian doctors, and
|
| Abetalipoproteinemia is a rare inherited
| |
| | others frequently prescribed d-alpha
|
| disorder of fat metabolism that results
| |
| | tocopherol for tens of thousands of
|
| in poor absorption of dietary fat and
| |
| | cardiac patients, in many cases for
|
| vitamin E. The vitamin E deficiency
| |
| | decades, in the range of 450-3200 IU/day.
|
| associated with this disease causes
| |
| | The Shute brothers did carefully limit
|
| problems such as poor transmission of
| |
| | the amount administered to 90-150 IU/day
|
| nerve impulses, muscle weakness, and
| |
| | for chronic rheumatic heart disease, and
|
| degeneration of the retina that can cause
| |
| | used lower starting dosages first. No
|
| blindness. Individuals with
| |
| | information in the metastudy addressed
|
| abetalipoproteinemia may be prescribed
| |
| | natural vitamin E blends, mixed
|
| special vitamin E supplements by a
| |
| | tocopherols, in use since before 1940.
|
| physician to treat this disorder.
| |
| | Use during pregnancy Recent studies into
|
| Also, in adults, erythrocyte membrane
| |
| | the use of both Vitamin C and E as
|
| fragility results as the erythrocytes are
| |
| | possible help in preventing oxidative
|
| oxidized.
| |
| | stress leading to pre-eclampsia has
|
| Vitamin E and heart disease Preliminary
| |
| | failed to show any benefit, but did
|
| research has led to a widely held belief
| |
| | increase the rate of babies born with a
|
| that vitamin E may help prevent or delay
| |
| | low birthweight in one study.
|
| coronary heart disease.
| |
| |
|
