The ABC's of E (Vitamin E)

A Look at Vitamin E

Vitamin E is not a single substance. It includes two classes of compounds, the tocopherols and the tocotrienols, that come from plants. The most biologically active form of vitamin E is alpha-tocopherol. Vitamin E can be expressed either in International Units (IUs) or Tocopherol Equivalents (TEs).

Vitamin E was discovered in the early 1920s by H.M. Evans and K.S. Bishop when they recognized that a dietary factor from plants was necessary for reproduction in rats. It was not until the 1930s, however, that the actual factor -- chemically called "tocopherol," meaning "life-giving"-- was isolated from wheat germ oil.

Sources of Vitamin E

Although vitamin E is widespread in foods, the majority of vitamin E in the diet comes directly or indirectly from natural vegetable oils in the form of margarine, salad dressings, nuts and shortenings. "Specialty" oils, such as wheat germ oil and walnut oil, have the highest concentrations of vitamin E. These are followed by sunflower, cottonseed, safflower, palm, canola, corn, soybean, peanut and olive oils. The vitamin E content of margarine products ranges from 1.3 to 5.4 IUs per tablespoon, depending on the type of oil used in the product. Oils commonly used for margarine products are corn, sunflower, safflower, soybean and canola.

Vitamin E for Good Health

In April of 2000, the National Academy of Sciences (NAS) increased the Recommended Daily Intake (RDI) for vitamin E to 15 milligrams for both men and women. Previously, the daily recommendation was 10 milligrams for men and eight milligrams for women. According to the NAS report, numerous epidemiological studies indicate that foods containing antioxidants (such as vitamin E) may have a positive effect on chronic disease, which provided the rational for increasing the daily intake recommendation. Depending on the type of margarine selected, a one tablespoon serving may provide up to 25 percent of the new RDI, making margarine a recognized source of vitamin E. Oils commonly used for margarine products are corn, sunflower, safflower, soybean and canola. Animal fats such as butter and milk fat have negligible amounts of vitamin E.

Vitamin E - The Disease Fighter

Antioxidant nutrients like vitamin E play a significant role in protecting the body against damage that can be caused by free radicals. Free radicals are substances that are formed by everyday bodily processes and can come from the environment. As an antioxidant, vitamin E is of particular importance since it helps to protect low-density lipoproteins and other lipid-rich body constituents against the oxidation process that leads to the development of heart disease and strokes, according to the January 1996 American Heart Association (AHA) Disease Statement on Antioxidant Vitamins. Vitamin E also serves as the body's primary defense against damage to cell membranes that are vital to human health.

An increasing amount of evidence suggests that lipoprotein oxidation and its biological effects can be reduced by antioxidants -- both in the diet and in supplements. Of all the antioxidants, vitamin E has the strongest evidence supporting its role in protection against the development of cardiovascular disease.

A link exists between vitamin E intake and coronary artery disease incidence, according to epidemiological studies, the AHA noted. Animal studies suggest that vitamin E can slow the development of atherosclerosis. Furthermore, vitamin E inhibits lipoprotein oxidation in test tube experiments and in those with people.

While the mechanisms are unknown, some research studies suggest that vitamin E most likely works by preventing the formation of "bad cholesterol," known as LDL (low-density lipoproteins) and its absorption by blood vessels.

Vitamin E Makes Research Headlines

Vitamin E recently has been studied for its protective effect against heart disease and other ailments. The most recent report, published in the New England Journal of Medicine (Kushi et al.), in 1996 found that people who ate foods rich in vitamin E, especially margarine, nuts and salad dressings, had a lower incidence of coronary heart disease -- one-half to two-thirds lower in women who did not have heart disease when they first entered the study. A more recent study from this same study group published in the May 2000 issue of the American Journal of Clincial Nutrition , found a similar association between women who ate diets that contained the most vitamin E-rich foods and incidence of cerebrovascular disease. In fact, death from stoke was 60 percent lower among those in the highest quintile of vitamin E intake from foods compared to those in the lowest quintile. Other antioxidant vitamins (e.g., vitamin C) or vitamin E supplements were not shown to have any protective effect.

Other studies have examined the effect of vitamin E supplements on the heart. A recent report published in the British medical journal The Lancet found that vitamin E supplements were associated with a reduced incidence of heart attack -- by 75 percent when taken daily by people with heart disease. In two other studies, published in 1993 in the New England Journal of Medicine, researchers suggested that taking vitamin E supplements daily for at least two years reduced the risk of heart disease by up to 40 percent in healthy men and women.

According to the government's 2000 U.S. Dietary Guidelines for Americans, however, vitamin supplements do not supply all of the nutrients and other substances present in foods that are important to health. Daily vitamin supplements are usually not needed by people who eat the variety of foods depicted in the Food Guide Pyramid.

The AHA does not recommend the use of antioxidant vitamin supplements until more complete data are available, according to its January 1996 statement. The AHA continues to recommend that Americans eat a variety of foods daily from all of the basic food groups.

USDA Chart of Vitamin E Content of Foods¹

¹Information based on the USDA Nationwide Food Consumption Survey (NFCS) 1987-88 (106).
²Food consumed by participants in the 1987-88 NFCS during 3 days of data collection.

Excerpted from Packer, L., Fuchs, J., Vitamin E in Health & Disease, Marcel Dekker, Inc., N.Y., 1993.