Vitamin E
If there were a report card grading the different vitamins, "E" could stand for "excellent." This important vitamin aids in immune system improvement and cancer prevention. Vitamin E teams up with vitamins A and C to provide the body with maximum antioxidant protection.
Why People Need Vitamin K
Vitamin E is special because it is especially good at providing protection to the cell membranes against free radicals. Damage to cell membranes is frequently the first step that can lead to such problems as heart disease, cancer and other health problems.
The reason vitamin E works so well as an antioxidant is because it is a fat-soluble vitamin, and the cell membranes are mostly made up of fat. Vitamin E enters the membrane and prevents free radicals from coming through.
But vitamin E does not simply work alone. It also teams up with beta carotene and vitamins A and C (the other major antioxidant vitamins) to give the body extra protection.
Vitamin E is actually a family of different compounds which all work together to protect the body against roaming free radicals. This particular family is divided into two branches: tocopherols and tocotrienols.
- Tocopherols - This clan has four members: alpha, beta, gamma and delta tocopherol. For many years researchers believed only alpha-tocopherol was really important. This was due to the fact that alpha-tocopherol is the most common and has the most active form, and is the one that works the hardest in the body. However, scientists now know the other tocopherols also do a good job of fighting free radicals. Gamma-tocopherol seems to make the best effort in protecting against free radicals from nitrogen oxides, the substances that make acid rain. Gamma-tocopherol is only about 20 percent as active as alpha-tocopherol.
- Tocotrienols - Also called alpha, beta, gamma and delta, these members of the E family are found in plant foods such as barley and rice. Although they do have antioxidant powers, they are not as active as tocopherols. This group may be even more effective at protecting against some types of free radicals, such as the peroxyl radical (which is formed when high-energy radiation such as ultraviolet light bombards the body). Tocotrienols may also help to prevent cancer and lower cholesterol.
Vitamin E Requirements
The recommended daily value for vitamin E was adjusted in 2000 by the Institute of Medicine. The amount now recommended for women was raised to 15 mg, but many nutritionally-oriented health care practitioners believe this amount is still way too low.
This RDA is based on "natural" alpha-tocopherol, because that is the most active form of vitamin E. Nutritionists often measure vitamins in milligrams because foods contain mixed tocopherols. Scientists measure vitamins in International Units (or IUs) because that is the most active and common form. One mg of natural vitamin E is equal to 1.49 IUs, and 1 mg of synthetic vitamin E is equal to 1.1 IUs.
As is the case with many other RDAs, the amount for vitamin E is very small because it is the bare minimum needed to avoid deficiency. Larger doses (such as 400 IUs) or even more are still safe. In fact, many of the research studies which examine the value of vitamin E for preventing cancer, heart disease and other health problems use doses that are even higher.
When the Body is Deficient
A vitamin E deficiency does not have any dramatic immediate effects. However, if an individual does not get the RDA for a long period of time (several months or even years) the result can be nerve damage (especially to the nerves in the spinal cord) and sometimes damage to the retina in the eye. Because of this, the damage can be hard to diagnose and can take a long time to show up.
Serious vitamin E deficiencies are rare because almost everyone gets anywhere from 7 to 11 mg of vitamin E daily simply from the foods they consume. However, mild forms of vitamin E deficiencies are fairly common. In a 1999 study, nearly 30 percent of all U.S. adults were low on vitamin E. This deficiency can be particularly serious among African Americans, with about 41 percent registering low in vitamin E. For all people who are low in this vitamin, the reason can be traced to low dietary intake.
Symptoms of Vitamin E Deficiencies
As noted above, nerve damage and changes to the retina can be the result of a vitamin E deficiency. However, there are some medical conditions that can make a person become deficient in vitamin E. These include:
- Cystic fibrosis - People with this condition cannot digest fats well so they do not absorb enough vitamin E.
- Crohn's disease - Those individuals who suffer from Crohn's or ulcerative colitis cannot absorb vitamin E well through their intestines.
- Liver disease - Such people cannot use vitamin E properly.
- Low-fat, low-calorie diets - People on diets of this type may not be getting enough vitamin E from their food. It is also important to have some fat in the diet so the body is able to absorb vitamin E.
- Cholesterol drugs Questran and Colestid - These drugs block absorption of vitamin E and other fat-soluble vitamins.
In all of these cases, a physician should be consulted about taking vitamin E supplements.
Foods Containing Vitamin E
There are not many foods that contain vitamin E. The best food sources are seeds, wheat germ, nuts, and vegetable oils. Some vitamin E can be found in plant foods such as asparagus, avoacados, mangoes and sweet potatoes, but it is in very small amounts.
In general, vegetable oils have vitamin E but there is a lot of variation. Some 90 percent of the vitamin E in safflower oil is alpha-tocopherol, but corn oil only contains about 10 percent. There is vitamin E in soybean oil (used in many prepared salad dressings) but it is mainly gamma tocopherol.
Natural vitamin E is made from vegetable oil and synthetic vitamin E is made chemically. Natural vitamin E is more expensive but is also more active. This type is absorbed better and stays in the system longer.
References
- Alan H. Pressman and Sheila Buff.(2007). The Complete Idiot's guide to vitamins and minerals. New York : Alpha Books
- Brewer, S. (2010). The essential guide to vitamins, minerals and herbal supplements. London : Right Way
- Elson M. Haas, Md & Buck Levin, Phd, Rd.(2006). Staying Healthy with Nutrition: The Complete Guide to diet and nutritional medicine. Berkeley, Calif. : Celestial Art
- Holford, P. (2004). The optimum nutrition bible. London : Piatkus
- Holford, P & Lawson, S.(2008). Optimum Nutrition Made Easy How to achieve optimum health. London : Piatkus
- Lieberman, S. & Bruning, N. (2003). The Real Vitamin & Mineral Book. New York : Avery
- Rodale Health Books.(2009). Healing with vitamins : the best nutrients to slow, stop, and reverse disease. Emmaus, Pa. : Rodale
- Royston, A.(2003). Vitamins and minerals for a healthy body. Oxford : Heinemann Library
- The National Research Council.(1989). Recommended Dietary Allowances, 10th ed, National Academy of Sciences
- Werbach, M. (1993). Nutritional Influences on Illness. 2nd ed. Los Angeles: Third Line Press
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