Vitamin E was discovered in 1922, but it wasn’t until the 1930s that we began understanding its physiological effects. This article will discuss vitamin E, including its role in the body and its deficiency causes and symptoms. We’ll then discuss testing of Vitamin E and sources of vitamin E, including diet and supplements.
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What is Vitamin E?
Vitamin E is a fat-soluble vitamin that occurs in eight different chemical forms: alpha-, beta-, gamma-, and delta-tocopherol and alpha-, beta-, gamma-, delta-tocotrienol. Alpha-tocopherol is the body’s preferred version of vitamin E and is the most commonly found form in the blood and tissues.
After absorption through the gastrointestinal tract, vitamin E is taken up by the liver. All forms of vitamin E, except alpha-tocopherol, are broken down and excreted in the urine. Alpha-tocopherol is then bound to a carrier protein and taken to various tissues in the body.
What is Vitamin E’s Role in The Body
Vitamin E’s main function in the body is as an antioxidant. Antioxidants are compounds that neutralize free radicals, which are compounds that form reactive oxygen species (ROS). These compounds are damaging to cells and have been linked to cancer and cardiovascular disease. ROS are made as a natural byproduct during energy production and from various environmental exposures, including cigarette smoke, air pollution, and ultraviolet (UV) rays.
Speaking specifically of the cardiovascular system, Vitamin E protects LDL cholesterol from becoming oxidized by ROS. Oxidized LDLs can eventually form into clots, are a driver of cardiovascular disease, and may also be linked to other chronic conditions. Vitamin E also plays a role in vasodilation, or widening, of blood vessels, which may help to prevent clot formation and adherence.
Vitamin E can modulate immune function. Vitamin E impacts a specific type of immune cell called T-cells and can enhance communication between T-cells and strengthen their structure. Vitamin E also has the ability to modulate inflammatory molecules released by other immune cells. Vitamin E seems to have a protective role and may reduce the risk of respiratory and allergic diseases, including asthma.
What Causes Vitamin E Deficiency
As vitamin E is a fat-soluble vitamin, conditions with fat malabsorption, such as Crohn’s disease and cystic fibrosis, will increase the risk of a vitamin E deficiency. Additionally, the hereditary condition abetalipoproteinemia results in the inhibition of fat absorption. The genetic condition ataxia with Vitamin E deficiency (AVED) is characterized by the absence of the protein that carries vitamin E into the body and thus will cause a vitamin E deficiency. Premature babies with low birth weight are often vitamin E deficient.
Vitamin E Deficiency Symptoms
Vitamin E deficiency symptoms include:
- Numbness, pain, and weakness in the hands and feet (peripheral neuropathy)
- Balance and coordination problems (ataxia)
- Muscle weakness (skeletal myopathy)
- Vision problems due to damage to the retina of the eye (retinopathy)
- Impaired immune response
How to Test Vitamin E Levels
Vitamin E levels can be checked in the blood, such as the Vitamin E test by BioReference Laboratories. The reference range is 5.5-17 micrograms per milliliter (mcg/mL) for adults and 3-18.4 mcg/mL for children. Vitamin E can also be found on micronutrient tests such as Spectracell Micronutrient Panel.
How to Make Sure You Are Getting Enough Vitamin E in Your Diet
The Institute of Medicine at the National Academies formed a Food and Nutrition Board that created Dietary Reference Intakes (DRIs) for vitamins and minerals. One such DRI is the Recommended Dietary Allowance (RDA), defined as the average daily intake required to meet nutritional adequacy in 97-98% of the healthy population. In the absence of evidence to create an RDA, an Adequate Intake (AI) will be formed. AI is defined as a level assumed to meet nutritional adequacy.
RDAs of Vitamin E
Pregnant and lactating women often have different RDAs due to their unique nutritional requirements. Pregnant women aged 14+ years have a vitamin E RDA of 15mg. The RDA of vitamin E for lactating women aged 14+ years is 19 mg.
Als were formed for infants under 12 months. The AI for males and females from birth to six months is 4 mg. The AI for male and female infants six to 12 months is 5 mg.
Vitamin E is found in foods and supplements.
Food Sources of Vitamin E
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Vitamin E Supplements
There are natural and synthetic forms of Vitamin E. Natural sourced vitamin E is commonly labeled d-alpha-tocopherol and is also called RRR-alpha-tocopherol. Synthetic vitamin E is commonly labeled as dl-alpha-tocopherol and is also called all rac -alpha-tocopherol. One milligram of alpha-tocopherol equals 1 mg d-alpha-tocopherol and 2 mg dl-alpha-tocopherol.
The synthetic form dl-alpha-tocopherol is only half as active as the natural d-alpha-tocopherol form. Some supplements only contain alpha-tocopheral (in either the natural or synthetic forms) while others will contain a mix including other tocopherols too. Most supplements contain over 67 mg (100IU) of natural vitamin E; this is well over the RDA for vitamin E. Excessive amounts of vitamin E via supplements may pose an increased risk for hemorrhagic stroke, although, in one of the studies, the participants were also smokers and the other study had concurrent use of aspirin. Yet, because of this, the FNB established Tolerable Upper Intake Levels (ULs) based on the risk of a hemorrhagic event. ULs are defined as the maximum daily intake unlikely to cause an adverse reaction.
Upper Limits (ULs) for Vitamin E
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In 2020 the Food and Drug Administration began using new Nutrition Facts and Supplement Facts labels. Prior to 2020, vitamin E was reported in international units (IU)s. Companies with under $10 million in annual sales may continue to report vitamin E on their products in IU units. For conversion of mg to IUs, 1 mg of alpha-tocopherol is equivalent to 1.49 IU of the natural form or 2.22 IU of the synthetic form. For conversion of IUs to mg, 1 IU of the natural form is equivalent to 0.67 mg alpha-tocopherol, and 1 IU of the synthetic form is equivalent to 0.45 mg of alpha-tocopherol.
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Summary
Vitamin E, primarily through alpha-tocopherol, has potent antioxidant functions as well as immune and inflammatory actions. Testing vitamin E levels can be a great way to ensure its status is adequate in the body. In the event that vitamin E levels are low, diet and supplements, or a combination of both, can aid in replenishing levels.
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