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PROMOTES Antioxidant Function Cardiovascular Function Blood Vessel Function Cell Membrane Stability Healthy Cells Immune System Function Nervous System Function Normal Hormone Activity Glucose Control
PROTECTS AGAINST Free Radicals Damage to Cell Membranes Inflammation Muscle Cramping Menstrual Cramping Red Blood Cell Rupture Blood Vessel Damage Some Skin Conditions Blood Clots
Suggested dose for supplementaltion of vitamin E is 400iu a day.
Overview Vitamin E was discovered by two scientists, Bishop and Evans, in 1932. They isolated the pure substance from wheat germ in 1936 and described it's structure in 1938. They gave it the name tocopherol derived from the Greek tokos, meaning offspring and phero, meaning to bring forth. It was determined that this substance was necessary for reproduction in rats and was referred to as the antisterility vitamin. Unfortunately, it was found to not have this activity for human beings as there are many more complexities to human sterility.
Vitamin E is not a single substance and should not be treated as such. It is at least eight different naturally occurring micronutrients bound together and found in foods. There are four of the tocopherols: d-alpha-tocopherol, d-beta-tocopherol, d-delta-tocopherol, and d-gamma-tocopherol and four of the tocotrienols: d-alpha-tocotrienol, d-beta-tocotrienol, d-delta-tocotrienol, and d-gamma-tocotrienol. D-alpha-tocopherol has been described as having the highest potency and is the most abundant to be found. As such it is the compound that is usually meant when referring to vitamin E. This is unfortunate as all eight have unique and useful functions and seem to balance each other.
Pure vitamin E compounds easily oxidize. They are frequently manufactured as acetate or succinate esters to slow the oxidative process. Some studies report that natural vitamin E has about 50% greater bioavailability than synthetic vitamin E.
Supplementation with synthetic, i.e.. just alpha-tocopherol, in contrast to the mixed tocopherols, can decrease plasma gamma-tocopherol concentrations by 30-50%, potentially creating an imbalance in the body's antioxidant system. This scenario in an individual who is suffering an illness where overall antioxidants are decreased, "vitamin E" as just d-alpha-tocopherol becomes an prooxidant. (see Function in the Body section)
Also, all fractions of natural vitamin E are in the RRR racemic form. Synthetic vitamin E is a mixture of sterioisomers and only one of these is comparable to naturally occurring RRR alpha-tocopherol. The others are not native to our diet. They seem to be antagonistic to the naturally occurring substances.
Reliance on processed foods as the main food source can contribute to depletion of the vitamin E group. Intolerance of fatty foods or food allergies such as gluten sensitivity may interfere with the availability and/or absorption of this vitamin. Low levels of selenium can contribute to depletion. So can a large amount of polyunsaturated fatty acids in the diet.
Symptoms of depletion include: -Dry skin -Dull hair that is brittle -Rupture of red blood cells resulting in anemia -Easy bruising -Premenstrual Syndrome -Fibrocystic breasts -Hot flashes -Eczema -Psoriasis -Cataracts -Benign Prostatic Hypertrophy (enlarging of the prostate) -Poor wound healing -Muscle weakness -Sterility
Some cholesterol lowering drugs and weight loss drugs deplete vitamin E.
See DRUG DEPLETETION TABLE for specific drug information.
Vitamin E is destroyed or altered by heat and oxidation during food processing primarily, but also cooking at high heat levels.
Vitamin E naturally occurs in wide availability. The primary sources are vegetable and seeds oils.
Other good sources: -Asparagus -Avocados -Broccoli -Brussel Sprouts -Dried Prunes -Leafy Greens -Nuts -Peaches -Seeds -Spinach -Wheat Germ -Whole Wheat Products -Whole Grain Breads and Cereals
None Known.
The vitamin E family is the body's most important fat soluble antioxidants. Gamma-tocopherol and gamma-tocotrienol act to reduce damage from nitrogen radicals produced by the activity of nitric oxide (NO), a signal molecule important for communication between cells of the nervous system, the vascular system as gatekeeper of blood flow to organs and regulator of blood pressure, and the immune system as a weapon against infections and tumor cells. (The drug Viagra® is designed to increase NO's affect thus increasing blood flow to the penis.) Even though alpha-tocopherol is the star of this family, it is the gammas that either reduce nitrogen dioxide (NO2) back to NO or react with it to form a harmless compound.
Vitamin E should be known as the vitamin of eights. Alpha-tocopherol, known to be the most biologically active of the eight main vitamin E compounds, can exist in eight different forms. Only half are known to be useful in the body. Alpha-tocopherol makes up about 80% of the normal blood plasma level of the vitamin E group and it is continually being recycled by the liver. It is bound to the high density lipoproteins (HDL), the "good" cholesterol. It is a single oxidant scavenger and does not appear to inhibit lipid oxidation caused by two electron oxidants, a process in the late stages of athrogenesis, the plaque buildup in the artery walls. In other words, it has been shown that two electron oxidants are the main cause for low density lipoproteins (LDL), the "bad" cholesterol, to be oxidized and hardened in the artery wall. Alpha-tocopherol is not effective in limiting this process. This was reported in a study published in CIRCULATION RESEARCH, 2002;90:333-339.
It has been reported that vitamin E reduces the amount of exercise induced free radical damage to the blood and tissues and reduce muscle injury. It may protect against cataracts and macular degeneration. It may help to alleviate premenstrual syndrome and dysphoria symptoms. Low levels of vitamin E are associated with greater risk for developing certain forms of cancer, including lung, oral, colon, rectal, cervical, pancreatic, and liver.
There have been hundreds of studies done between 1966 and August of 2004 looking at the use of "vitamin E" alone and in combination with other vitamins, minerals, and drugs in a vast array of populations with a variety of disease states ranging from cardiovascular disease to various eye disorders. A recent retrospective review of nineteen of these clinical trials with 135,967 volunteer participants was presented at the November 2004 American Heart Association annual meeting. It was titled "Meta-Analysis: High Dose Vitamin E Supplementation May Increase All-Cause Mortality". This meta-analysis concluded that high dose vitamin E, defined as greater than 400iu per day, increased all cause mortality by 4%. The Annals of Internal Medicine posted it on their website for early release, an action taken only when a study reports clinically urgent results. This report surprised and alarmed the medical community. It created an almost immediate buzz in the mainstream media.
But there's a problem here. A meta-analysis should analyze data from homogeneous populations using similar study protocols thus providing strength to the data combined for analysis. Not only did this meta-analysis combine very heterogeneous studies, but the vitamin E used in all but one of the studies was synthetic (see paragraph 3 & 4 in the Overview).
Upon close scrutiny, the conclusion by the authors of this meta-analysis is dubious. It glares, begging for consistent attention to the development and standardization of a more rational approach to evaluating supplementation of micronutrients in clinical trials. Supplementation regimens in trials designed to evaluate a micronutrient should ensure adequate intake of naturally identifiable substances, unless of course the study is to evaluate the effects of synthetic substances. Adequate intake is dependent on the manufacturing process to assure the nutrients bioavailablity. Poor quality supplements are bound to tightly to the fillers and transport media, not tested adequately for consistent potency, or being tainted with other chemicals that can alter the micronutrient's action. Also, supplements should remain just that - supplements and not take the place of a diet full of healthy nutrients. A diet such as this should be consistently prescribed in such clinical trials.
Recommended Dietary Allowance: The RDA -recommended daily allowance- for vitamin E is 400 international units (iu).
RDA/AI* (Adequate Intake)
AGE (YRS) AMOUNT in milligrams (mg) / day
Infants 0.0-0.5: 4 - 5* 0.5-1.0: 4 - 5*
Children 1-3: 6 - 7 4-8: 6 - 7
Males 9-13: 11 14-18: 11 19-30: 15 31-50: 15 51-70: 15 71+: 15
Females 9-13: 11 14-18: 11 19-30: 15 31-50: 15 51-70; 15 71+: 15
Pregnant: 15
Lactating: 19
Most individuals studied while taking high doses of vitamin E have not shown symptoms of toxic effects. There have been reports of headache, fatigue, nausea, double vision, weak muscle groups, and lower gastrointestinal upset with doses greater than 1000 mg a day.
The recent WOMEN"S ANGIOGRAPHIC VITAMIN AND ESTROGEN (WAVE) trial with 423 postmenopausal woman who had known coronary heart disease (CHD), showed that the combination of conjugated equine (horse) estrogen (Premarin® or Prempro®) at 0.625 mg a day taken with vitamin E and C, had higher total and cardiovascular death rates than the women taking the vitamin placebo. Routine use of this kind of estrogen with high dose vitamin E and C by postmenopausal women who have CHD may worsen the outcome of the disease. NOTE: In this study, the form of vitamin E used was not reported and when contacted, the researches were unsure of which form of vitamin E was used. They contacted the manufacturer and it was determined it was synthetic. (See paragraph 3 and 4 in the overview) |