Description of vitamin E
The Vitamin E plays an essential role in protecting the membrane of all cells in the body. It is antioxidant, that is to say, it contributes to the neutralization of free radicals in the body. In addition, it prevents or reduces the oxidation of low density lipoproteins (LDL). This LDL oxidation is associated with the onset of atherosclerosis and therefore with cardiovascular disease. Vitamin E also has anti-inflammatory, antiplatelet and vasodilatory properties. These effects, which are not linked to its antioxidant activity, also play a cardioprotective role.
Under the term of Vitamin E, there are 4 forms of tocopherols and 4 forms of tocotrienols. Among the 4 tocopherols, alpha-tocopherol is the most common form of vitamin E in the body. It is also the unit of measurement for the recommended nutritional intake and the vitamin E content of foods. Most supplements on the market contain alpha-tocopherol. The mention the reference ” mixed tocopherols On a label indicates that the product contains, in addition to alpha-tocopherol, beta-tocopherol, gamma-tocopherol and delta-tocopherol, the other compounds of vitamin E.
The body absorbs the natural form of vitamin E better than the synthetic form. There is controversy about the equivalence factor between these 2 forms, but a consensus seems to have been established among the experts, around a ratio of 1.5. Therefore, 400 IU of vitamin E in natural form equivalent to 600 IU in synthetic form.
Some practitioners recommend using only supplements that come in a natural form rather than taking 1 ½ doses of synthetic supplements. The Other names section, at the beginning of this sheet, allows you to check the list of ingredients on the packaging and to distinguish the natural source supplements of those containing synthetic tocopherols.
In fortified foods, it is usually synthetic vitamin E that is used by manufacturers.
Food sources of vitamin E
In general, nuts, seeds, vegetable oils and, to a lesser extent, green leafy vegetables are good sources of Vitamin E. However, note that peanuts and pistachios contain less vitamin E than, for example, almonds, hazelnuts and sunflower seeds. However, to obtain therapeutic or preventive dosages (in general much higher than the ANR), foods are not suitable, since it would be necessary to consume large amounts of fat, vitamin E being mainly present in fatty foods.
|Wheat germ oil||15 ml (1 tbsp)||21 mg|
|Unblanched almonds, dry roasted or in oil or dehydrated||60 ml (1/4 cup)||9-18 mg|
|Dry roasted sunflower seeds||60 ml (1/4 cup)||8 mg|
|Hazelnuts, unblanched oats, dry roasted||60 ml (1/4 cup)||5-8 mg|
|Sunflower oil||15 ml (1 tbsp)||6 mg|
|Breakfast cereals, 100% bran (All bran type)||30 g (1 oz)||3-5 mg|
|Canned tomato paste||60 ml (1/4 cup)||3 mg|
|Roasted peanuts in oil||60 ml (1/4 cup)||2-3 mg|
|Canned sardines with bones||100 g (3 1/2 oz)||2 mg|
|Lawyer||½ avocado (90 g)||2 mg|
|For other dietary sources of vitamin E, see our Vitamin E Nutrient List, where this table comes from.|
Vitamin E deficiency
The risk of deficiency serious in Vitamin E is very low in developed countries. It is usually linked to diseases that cause problems with fat absorption (for example, cystic fibrosis, celiac disease and Crohn’s disease). It is especially in the long term that the symptoms of deficiency manifest themselves, generally by neurological problems attributable to poor nerve conduction.
However, the recommended nutritional intake (ANR) in Vitamin E, which is set at 15 mg of alpha-tocopherol (the natural form) per day, would not be fully met by the diet of North Americans. According to the results of a survey carried out in the United States between 2001 and 2002, Americans would benefit from consuming significantly more seeds and nuts rich in vitamin E, such as almonds or sunflower seeds, if they want to reach the ANR. This advice probably applies to Quebecers and Canadians, whose diet is similar to that of their neighbors to the south.
In addition, still according to American authorities, people who follow a low fat diet should choose their food, and especially their fat, carefully, to ensure sufficient vitamin E intake.
Vitamin E history
In 1922, California researchers discovered a fat-soluble substance in wheat germ and lettuce and named it “Factor X”. They determined that this substance was essential for the reproductive function of rats. Factor X was then called Vitamin E, then in 1936, tocopherol, a word from the Greek (tokos : childbirth, race and pherein : porter) which recalled its importance for the reproductive system of animals.
In 2000, American and Canadian medical authorities significantly increased the recommended nutritional intake (RDA) of vitamin E, from 10 mg to 15 mg per day for people over 14 years of age.
Vitamin E research
|Vitamin E effective?
Vitamin E has been the subject of a multitude of scientific research in recent years. So far, none has led to a clear demonstration of its therapeutic efficacy for a specific use.
This lack of clinical effects causes controversy which continues as the negative results of certain long-term trials are published, the last dating from 2008 and 2009. Some data seemed more convincing when vitamin E was associated with other antioxidants like vitamin C, beta carotene or selenium, but again, recent large trials have been inconclusive.
As a result of these inconclusive trials and their meta-analysis, several researchers have concluded that taking vitamin E, even in the long term, has no efficacy in preventing cardiovascular disease or cancer, for example.
However, other researchers are questioning the negative findings of clinical studies. They wonder if the target populations, the type and dosage of vitamin E used and the duration were adequate to detect the potential beneficial effects of vitamin E.
Some meta-analyzes have questioned the safety of taking regular vitamin E at dosages above 400 IU per day. Although the statistical analysis of this work is open to criticism, some researchers believe that in people with a level of oxidative stress normally low, taking high doses of vitamin E could lower this level below a critical level and would then pose a health risk.
- Menstrual problems: Vitamin E has shown positive but limited results in the treatment of disorders associated with menstruation. Doses of 200 IU or 500 IU daily for 5 days, starting 2 days before menstruation, reduced the duration and intensity of menstrual pain in a group of adolescent girls. Doses of 400 IU per day, administered as previously, also alleviated the symptoms of women with migraines menstrual. Vitamin E could also relieve symptoms of PMS.
In addition, according to a study published in 2010, women experiencing cyclic breast pain (cyclic mastalgia) felt some relief after taking 1,200 IU of vitamin E for 6 months.
- Strengthening the immune system of the elderly. From the age of 70, the aging is accompanied by a noticeable weakening of the immune system. It is characterized in particular by a lower efficiency of the immune cells which protect the organism against cancers and the infections. Researchers have linked this decline in immune function to a deficiency of certain nutrients, especially vitamin E. Several clinical trials support these observations by showing that from 100 mg per day, vitamin E supplements can improve the immune response of the elderly.
- Prevention of cardiovascular disease. An abundant scientific literature demonstrates that in vitro and in animals, vitamin E can limit the phenomenon of atherosclerosis. In humans, population studies have also been able to link food intake of vitamin E with reduced risk of cardiovascular disease. Despite this, clinical trials, some of them large, fail to convincingly show that vitamin E supplementation decreases this risk. Some researchers even go so far as to suggest that doses above 400 IU per day may increase the risk (see the box above “Safe Vitamin E?”).
Several hypotheses are put forward to try to explain this apparent contradiction. So vitamin E would only be beneficial to some people. For example, it would only warn cardiovascular diseases that in some type 2 diabetics, carrying a particular gene. Vitamin E also only protects against a certain type of stroke. Finally, its benefits would be more pronounced in women.
The dose and nature of vitamin E could also be important factors in its effectiveness. Some researchers suggest that tocotrienols would be more active than tocopherols.
In addition, many clinical trials are conducted in individuals aged 50 years or more, who already suffer from cardiovascular problems or in whom the atherosclerosis process is sufficiently advanced to mask the effects of vitamin E1. Supplementation trials in younger people may reveal more significant effects of vitamin E.
- Cancer prevention. The possibility that vitamin E could be used to prevent cancer has been the subject of several large-scale clinical studies. Unfortunately, the results as a whole are rather disappointing and the scientific community generally agrees that vitamin E supplements are not an effective way of reducing the risks of cancer, especially with regard to colorectal cancer and lung cancer. In the case of prostate cancer, vitamin E has only shown positive results for smokers where it seems to decrease the risk.
In addition, according to a preliminary test, a high dose of vitamin E (600 mg / 900 IU per day), taken during treatment for chemotherapy (ciplastine) and over the next 3 months, significantly reduced peripheral neuropathy, an adverse effect of chemotherapy.
|Faced with these results, the researchers wonder whether the dosages, the target populations and the duration of the supplementation should not be reviewed in order to better detect the possible beneficial effects of vitamin E18, 20. Many also believe that it is time to take a closer look at tocotrienols, less known compounds of vitamin E, but which have an activity antioxidant much higher than those of tocopherols.|
- Alzheimer’s disease and prevention of cognitive decline. Epidemiological data are contradictory as to the preventive effect of vitamin E on Alzheimer’s disease. The same is true from the point of view of clinical trials. However, all research is not abandoned and the explanation of these contradictions may be sought on the side of the type of vitamin E used.
- Parkinson disease. Large-scale epidemiological studies have found a correlation between a diet rich in vitamin E and reduced risk of Parkinson’s disease. However, this relationship was not found with the supplements vitamin E. In addition, a study of 800 volunteers suffering from an early stage of the disease showed that taking 2,000 IU of vitamin E per day for 8 years had no effect on the course of the disease.
- Macular degeneration. In a study published in 2001, 3,640 subjects aged 55 to 80 were followed for 6 years (AREDS study). In those with a moderate or advanced form of macular degeneration (category 3 and 4), taking a cocktail providing 500 mg of vitamin C, 400 IU of vitamin E, 15 mg of beta-carotene and 80 mg of zinc oxide reduced disease progression by about 25% compared to placebo. This trial, however, does not allow to conclude on the specific efficacy of vitamin E. Especially since all the results of several clinical trials point to a lack of effect of Vitamin E regarding the prevention of this eye disorder.
- Prevention of cataracts. Results of several epidemiological studies suggest that vitamin E may have a protective effect against the formation of cataracts. However, in several trials involving thousands of subjects, prolonged intake of vitamin E, alone or in combination with other antioxidants, had no effect on the incidence or progression of this disease. Only a study of 297 subjects indicates that taking a supplement containing several antioxidants, including 600 IU of vitamin E, for 2 to 4 years, slightly reduced the progression of cataracts.
- Diabetes prevention. Vitamin E does not seem to have an effect on the risk of developing diabetes as well in healthy 45-year-old women or in those at high risk for cardiovascular disorders, than in smokers aged 50 to 69. In addition, taking supplements for diabetics would not improve the control of their blood sugar, except perhaps in those with vitamin E deficiency.
Concerning the complications of diabetes, vitamin E could have a preventive effect on the cardiovascular diseases of a particular group of type 2 diabetics (see “Prevention of cardiovascular diseases” above), but it would be ineffective in all other cases.
- Arthritis. At present, clinical trials do not conclude that taking vitamin E is effective in reducing the symptoms of rheumatoid arthritis and osteoarthritis. A large study of 39,000 women aged 45 and over has even shown that taking a supplement of 600 IU of vitamin E every 2 days for 10 years has had no effect.
|Although vitamin E is frequently used topically to aid in the healing of minor injuries and burns and to reduce scarring, data on its effectiveness is anecdotal at best.|
The Vitamin E has been the subject of many other studies whose results are either inconclusive or contradictory. This is the case, for example, with the prevention of respiratory infections and preventing or treating allergies.
|Note. Vitamin E supplements have other therapeutic uses which are subject to specific medical monitoring and which are linked to deficiency of vitamin E. This deficiency results from disorders of the absorption of fat caused by diseases like cystic fibrosis, celiac disease, Crohn’s disease, abetali poproteinemia and chronic cholestasis. Very high doses of vitamin E are also sometimes used, under medical supervision, to reduce the symptoms of tardive dyskinesia.|
- Theoretically, the effects of high doses of vitamin E (1,000 IU per day) could be added to those of plants and supplements whose action is anticoagulant or antiplatelet (garlic, ginkgo biloba, ginseng, etc.).
- Theoretically, the effects of high doses of vitamin E (1,000 IU per day) could be added to those of synthetic drugs whose action is anticoagulant or antiplatelet (warfarin, heparin, aspirin, etc.).
- Medicines like colestipol and cholestyramine (reducers of cholesterol and blood lipids) and those that decrease the absorption of fats (orlistat) may reduce the absorption of vitamin E.
- Anticonvulsant medications (such as phenytoin and carbamazepine) can reduce the blood level of vitamin E.
- Isoniazid, a tuberculosis drug, can reduce the absorption of vitamin E.
- Olestra fat substitute (not authorized in Canada) may reduce the absorption of vitamin E.
Vitamin E: recommended dosage
- Take 200 IU to 500 IU vitamin E daily for 5 days, starting 2 days before menstruation.
- Most authors recommend a daily dosage ranging from 200 IU (134 mg) to 400 IU (268 mg) of vitamin E natural to be taken continuously.
Recommended nutritional intake (RDA) of vitamin E
(d-alpha-tocopherol, the natural form)
(mg / IU *)
|0 to 6 months||4 mg / 6 IU **|
|7 to 12 months||5 mg / 7.5 IU **|
|1 to 3 years||6 mg / 9 IU|
|from 4 to 8 years old||7 mg / 10.5 IU|
|9 to 13 years old||11 mg / 16.5 IU|
|14 and over||15 mg / 22.5 IU|
|Pregnant women||15 mg / 22.5 IU|
|Nursing women||19 mg / 28.5 IU|