Vitamin E: Sources, Health Benefits and Deficiency
Vitamin E is a fat soluble vitamin with antioxidant properties present in lipids and fat tissues of the body. As an antioxidant it helps protect cells from damage caused by overactive free radicals. Free radicals are unstable molecules with missing electrons that form in the body when cells burn oxygen. Vitamin E is most effective when taken in conjunction with vitamin C, another potent antioxidant.
Vitamin E occurs in foods in two basic forms, i.e. as tocopherols and tocotrienols while there are eight isomers of vitamin E altogether, including alpha, beta, gamma and delta tocopherol and alpha, beta, gamma and delta tocotrienol. These various types of vitamin E have different potencies when in human body, with alpha-tocopherol being the most accessible and, therefore, most frequently used in supplements.
The recommended dietary allowances (RDAs) for vitamin E expressed in milligrams of alpha-tocopherol equivalents are 15mg per day (22.5 IU) for teens over 14 and adults and 19 mg per day (28.5 IU) for lactating women. For conversion purposes, 1mg of alpha-tocopherol equivalent is equal to 1.5 IU (international units). The upper level limit for vitamin E intake in people over 14 years of age is 1,000 mg per day or 1,500 IU.
Potential Health Benefits of Vitamin E
Adequate levels of vitamin E in the body are vital for proper functioning of the reproductive system, muscles and nerves. However, vitamin E is probably best known for its antioxidant properties that help protect the body’s cells from harmful activity of free radicals. Antioxidants neutralize free electrons by binding with them and thus prevent them from causing damage to the cells. For example, vitamin E helps prevent the oxidation of the so-called “bad” LDL cholesterol. It was found that tocopherols (a form of vitamin E) attach to lipoproteins (cholesterol carriers) and prevent them from attaching to artery walls, which could result in blocking blood vessels. This is believed to lower the risk of heart disease and stroke.
Furthermore, vitamin E can prevent the oxidation of polyunsaturated fatty acids and protect essential fatty acids and vitamin A levels in the body. Vitamin E is also believed to help prevent several types of cancer as well as some degenerative illnesses of the cardiovascular, respiratory and neurological systems. Protecting the lining of blood vessels and sexual glands from potential damage caused by harmful chemicals contained in food and inhaled toxins is yet another health benefit of vitamin E.
Although deficiency of vitamin E is rare, it may sometimes occur in premature babies with extremely low birth weights. In addition, people who have digestive disorders associated with poor fat absorption may experience vitamin E deficiency. Problems related to low levels of vitamin E may also occur in people on low-fat diets. Other factors that can contribute to vitamin E deficiency include zinc deficiency and genetic abnormalities in the alpha-tocopherol transfer protein.
People who are deficient in vitamin E may be more vulnerable to damage caused by free radicals from food and the environment. The most common symptoms of prolonged vitamin E deficiency include loss of muscle coordination and reflexes, neuromuscular dysfunction of the spinal cord and retina and impaired vision and speech.
Excessive levels of dietary vitamin E do not usually pose health problems. But, excessive use of vitamin E supplements may cause complications, such as impairing the blood-clotting action of vitamin K or enhancing the effects of anticoagulant medications. This may lead to increased risk of bleeding and other side effects such as dizziness or upset stomach.
Dietary Sources of Vitamin E
In general, any food containing unsaturated fats is a good source of vitamin E. This includes unsaturated vegetable oils made of canola, cottonseed, corn, soybean, safflower and sunflower, nuts such as almonds, hazelnuts and peanuts, seeds, vegetables like asparagus or green leafy vegetables, egg yolks, liver, olives and wheat germ. Vitamin E is also added to processed foods as a preservative. Because vitamin E is easily destroyed during heat processes, it is best to obtain it from fresh or lightly cooked meals.
Although people should get all of their vitamin E from diet rather than from supplements, sometimes supplementation may be necessary. This applies to people who cannot absorb fat due to certain diseases or those who cannot secrete bile which aids fat digestion.
Remember that too much vitamin E from supplements can cause side effects and can interfere with medications such anticoagulants. Therefore, supplements should not be taken without first asking your doctor.