Summary
Found in nuts, seeds and unprocessed vegetable oils, Vitamin E is a well-known antioxidant which protects fatty acids and cell membranes. It is essential for normal reproductive health in both males (testicular health) and females (foetal health). Vitamin E may also reduce many chronic illnesses and has a wide margin of safety.
Details
Vitamin E is a complex substance that comes in eight forms: alpha-tocopherol, beta-tocopherol, gamma-tocopherol, delta-tocopherol, and the esters of each. Alpha-tocopherol ester is the most common form used in manufactured foods and supplements, while gamma-tocopherol is the most common form in the natural food supply (though the most common form can vary by geographic region) (Traber 2006). It is undetermined whether there are different health benefits among these different forms.
Antioxidants protect cells from the damaging effects of free radicals, which are molecules that contain an unshared electron. Free radicals damage cells and might contribute to the development of cardiovascular disease and cancer. Unshared electrons are highly energetic and react rapidly with oxygen to form reactive oxygen species (ROS). The body forms ROS endogenously when it converts food to energy, and antioxidants might protect cells from the damaging effects of ROS. The body is also exposed to free radicals from environmental exposures, such as cigarette smoke, air pollution, and ultraviolet radiation from the sun. ROS are part of signaling mechanisms among cells.
Vitamin E is a fat-soluble antioxidant that stops the production of ROS formed when fat undergoes oxidation. Scientists are investigating whether, by limiting free-radical production and possibly through other mechanisms, vitamin E might help prevent or delay the chronic diseases associated with free radicals.
In addition to its activities as an antioxidant, vitamin E is involved in immune function and, as shown primarily by in vitro studies of cells, cell signaling, regulation of gene expression, and other metabolic processes. Alpha-tocopherol inhibits the activity of protein kinase C, an enzyme involved in cell proliferation and differentiation in smooth muscle cells, platelets, and monocytes. Vitamin-E–replete endothelial cells lining the interior surface of blood vessels are better able to resist blood-cell components adhering to this surface. Vitamin E also increases the expression of two enzymes that suppress arachidonic acid metabolism, thereby increasing the release of prostacyclin from the endothelium, which, in turn, dilates blood vessels and inhibits platelet aggregation.
Sources
| Food | (mg) |
| Wheat germ oil, 1 tablespoon | 20.3 |
| Sunflower seeds, dry roasted, 1 ounce | 7.4 |
| Almonds, dry roasted, 1 ounce | 6.8 |
| Sunflower oil, 1 tablespoon | 5.6 |
| Safflower oil, 1 tablespoon | 4.6 |
| Hazelnuts, dry roasted, 1 ounce | 4.3 |
| Peanut butter, 2 tablespoons | 2.9 |
| Peanuts, dry roasted, 1 ounce | 2.2 |
| Corn oil, 1 tablespoon | 1.9 |
| Spinach, boiled, ½ cup | 1.9 |
| Broccoli, chopped, boiled, ½ cup | 1.2 |
| Soybean oil, 1 tablespoon | 1.1 |
| Kiwifruit, 1 medium | 1.1 |
| Mango, sliced, ½ cup | 0.7 |
| Tomato, raw, 1 medium | 0.7 |
| Spinach, raw, 1 cup | 0.6 |
Safety considerations and limits
Scientific literature contains many reports of safe continuous intake of vitamin E supplements at levels that are many multiples of the current RDA. The evidence comes from different types of studies, ranging from observational studies of a few subjects to large randomized, controlled intervention trials looking for effects on cancer, cardiovascular disease, and other disorders. There have been dozens of published studies with documented safety observations for vitamin E supplements, involving a total of more than 100,000 people.
The Council for Responsible Nutrition recommends an upper limit of 1,000 mg (1.600 IU) per day for healthy adults who are not taking any anticoagulant drug.