Vitamin E: Benefits, Dosage, and Safety

What vitamin e is

Vitamin E is the collective name for a group of eight fat-soluble compounds (alpha-, beta-, gamma-, and delta-tocopherol and the corresponding four tocotrienols) with antioxidant activity. Alpha-tocopherol is the only form recognized to meet human requirements and the only one the liver preferentially maintains in plasma via the hepatic alpha-tocopherol transfer protein. Naturally sourced vitamin E is RRR-alpha-tocopherol (labeled d-alpha-tocopherol); the synthetic form is all-rac-alpha-tocopherol (labeled dl-alpha-tocopherol) and is about half as biologically active by weight.

What it does

• Acts as a fat-soluble antioxidant that stops the production of reactive oxygen species formed when fat undergoes oxidation, protecting cells from free-radical damage (per ODS)
• Contributes to normal immune function (per ODS)
• Involved in cell signaling, regulation of gene expression, and other metabolic processes, shown primarily in in vitro cell studies (per ODS)
• Alpha-tocopherol inhibits protein kinase C activity, an enzyme involved in cell proliferation and differentiation in smooth muscle cells, platelets, and monocytes (per ODS)
• Supports endothelial cells lining blood vessels and increases release of prostacyclin, which dilates blood vessels and inhibits platelet aggregation (per ODS)

How much vitamin e per day

These are population reference values from the NIH and the Dietary Reference Intakes. They are targets for healthy people, not personal prescriptions. The last column is the Tolerable Upper Intake Level, the most you should get from all sources combined.

Deficiency and who is at risk

Frank vitamin E deficiency is rare, and overt deficiency symptoms have not been found in otherwise healthy people who get little vitamin E from their diets. When deficiency does occur, usually secondary to fat-malabsorption disorders or rare genetic conditions, signs include peripheral neuropathy, ataxia, skeletal myopathy, retinopathy, and impairment of the immune response. Severe deficiency from abetalipoproteinemia or ataxia with vitamin E deficiency (AVED) can cause nerve damage, muscle weakness, retinal degeneration leading to blindness, and loss of the ability to walk.

Who may need more

• People with fat-malabsorption disorders such as Crohn's disease, cystic fibrosis, or cholestatic liver disease who cannot absorb dietary fat and may require water-soluble forms
• People with the rare inherited disorders abetalipoproteinemia or AVED, who need large supervised doses
• Premature very low birth weight infants, under medical supervision
• Most healthy people meet needs through diet; national surveys show many Americans consume less than the RDA from food, though frank deficiency is still rare

Food sources

Nuts, seeds, and vegetable oils are the richest sources of alpha-tocopherol; green leafy vegetables and fortified cereals also contribute. Examples per serving: wheat germ oil 1 tablespoon (20.3 mg), sunflower seeds dry roasted 1 ounce (7.4 mg), dry roasted almonds 1 ounce (6.8 mg), sunflower oil 1 tablespoon (5.6 mg), safflower oil 1 tablespoon (4.6 mg), hazelnuts 1 ounce (4.3 mg), peanut butter 2 tablespoons (2.9 mg), corn oil 1 tablespoon (1.9 mg), boiled spinach half cup (1.9 mg), boiled broccoli half cup (1.2 mg).

Forms and absorption

Supplements typically provide only alpha-tocopherol, though mixed products with other tocopherols and tocotrienols exist. Natural (RRR-alpha-tocopherol; d- or D-labeled) exists as one stereoisomer and is about twice as biologically active by weight as synthetic (all-rac-alpha-tocopherol; dl- or DL-labeled), which contains equal amounts of eight stereoisomers, only four of which are retained by the body. Alpha-tocopherol is often esterified (alpha-tocopheryl acetate or succinate) to extend shelf life; the body hydrolyzes and absorbs these esters as efficiently as free alpha-tocopherol. Most vitamin-E-only supplements provide 67 mg or more (100 IU or more of natural vitamin E), well above the RDA. Water-soluble tocopheryl polyethylene glycol-1000 succinate is used for people with malabsorption.

Safety, excess and interactions

Too much

Research has not found adverse effects from vitamin E obtained from food. High-dose alpha-tocopherol supplements can cause hemorrhage and interrupt blood coagulation because they inhibit platelet aggregation and antagonize vitamin K-dependent clotting factors. Two clinical trials found an increased risk of hemorrhagic stroke among people taking alpha-tocopherol (one in Finnish male smokers taking 50 mg per day for about 6 years, and one in US male physicians taking 400 IU synthetic vitamin E every other day for 8 years). Two meta-analyses linked high-dose supplementation to small but statistically significant increases in all-cause mortality, with risk beginning to rise around 150 IU per day in one analysis, though the implications remain unclear and disputed. The SELECT trial found that 400 IU per day of synthetic vitamin E (180 mg) was associated with a statistically significant 17 percent increased risk of prostate cancer in healthy men.

Interactions to know

• Anticoagulant and antiplatelet medications (for example warfarin/Coumadin): vitamin E can inhibit platelet aggregation and antagonize vitamin K-dependent clotting factors, so large doses can increase bleeding risk, especially with low vitamin K intake; the amount needed for a clinically significant effect is unknown but probably exceeds 400 IU per day (per ODS)
• Simvastatin (Zocor) plus niacin: vitamin E taken with other antioxidants (vitamin C, selenium, beta-carotene) blunted the rise in HDL cholesterol, especially the cardioprotective HDL2 fraction, in people treated with the simvastatin-niacin combination (per ODS)
• Chemotherapy and radiotherapy: oncologists generally advise against antioxidant supplements during cancer treatment because they might reduce effectiveness by protecting cancer cells from oxidative damage, though evidence is mixed and further research is needed (per ODS)

How status is measured

Status is measured by serum or plasma alpha-tocopherol concentration, the only form maintained in plasma. ODS notes a primary limitation is the lack of validated biomarkers linking intake and status to clinical outcomes; the FNB has called for research to identify better biomarkers of vitamin E requirements.

Regulated as a dietary supplement ingredient under DSHEA, not as a drug; the FDA does not evaluate supplements for safety and effectiveness before marketing. The Daily Value (DV) for labeling is 15 mg for adults and children 4 years and older. Since January 2020 (with small manufacturers allowed until January 2021), Nutrition and Supplement Facts labels list vitamin E in mg rather than IU.

What the evidence supports

We grade the strength of evidence behind each common reason people take vitamin e, mirroring how the NIH describes it.