vitamin
Vitamin E: Natural vs Synthetic, IU to mg and Safety
Also known as alpha-tocopherol, d-alpha-tocopherol, dl-alpha-tocopherol, tocopheryl acetate, mixed tocopherols, tocotrienols
Short answer
Vitamin E is a fat-soluble nutrient, and alpha-tocopherol is the form people need [1]. Labels now list it in mg. Natural d-alpha-tocopherol is twice as active per mg as synthetic dl-alpha-tocopherol [1]. The adult RDA is 15 mg [1]. High-dose supplements can raise bleeding risk, especially with blood thinners such as warfarin [1].
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What is Vitamin E?
Vitamin E is the name for a group of eight fat-soluble compounds, and alpha-tocopherol is the only form recognized to meet human needs [1]. It acts as an antioxidant that stops the production of reactive oxygen species formed when fat oxidizes [1]. The body also uses it in immune function and in cell signaling [1].
Forms of Vitamin E you'll see on labels
d-alpha-tocopherol (RRR-alpha-tocopherol)
The natural form. 1 mg counts as 1 mg of vitamin E (alpha-tocopherol) [1].
dl-alpha-tocopherol (all rac-alpha-tocopherol)
The synthetic form. It contains eight stereoisomers and the body keeps only four, so it is half as active by weight: 2 mg counts as 1 mg [1].
Tocopheryl acetate or tocopheryl succinate
Esters used to extend shelf life. The body breaks them down and absorbs them as well as plain alpha-tocopherol [1].
Mixed tocopherols and tocotrienols
Most supplements provide only alpha-tocopherol, but some add other tocopherols and tocotrienols [1]. US recommendations count alpha-tocopherol only [1].
Tocopheryl polyethylene glycol-1000 succinate (TPGS)
A water-soluble form that people with fat-malabsorption conditions sometimes need [1].
How much Vitamin E do adults need?
NIH lists these Recommended Dietary Allowances (RDA) for people 14 and older, in mg of alpha-tocopherol. Reference values, not a personal recommendation.
| Group | Amount per day |
|---|---|
| Men 14+ | 15 mg |
| Women 14+ | 15 mg |
| Pregnancy | 15 mg |
| Breastfeeding | 19 mg |
Upper limit: 1,000 mg/day of supplemental alpha-tocopherol for adults 19+, including pregnancy and breastfeeding (about 1,500 IU natural or 1,100 IU synthetic) [1]
How Vitamin E appears on a label
New Supplement Facts labels list vitamin E in mg; older labels used IU [1]. To convert IU to mg, 1 IU of natural vitamin E = 0.67 mg and 1 IU of synthetic = 0.45 mg [1]. To go the other way, 1 mg = 1.49 IU natural or 2.22 IU synthetic [1]. "d" or "D" on the label means natural; "dl" or "DL" means synthetic [1]. The Daily Value is 15 mg [1]. Most vitamin E-only supplements provide 67 mg (100 IU natural) or more, well above the RDA [1].
When to take Vitamin E
No source we checked names a best time of day for vitamin E. NIH notes that the digestive tract needs fat to absorb vitamin E, which is why people with fat-malabsorption problems are more likely to run low [1].
What to keep apart from Vitamin E
Warfarin and other anticoagulant or antiplatelet medicines
Vitamin E can inhibit platelet clumping and work against vitamin K clotting factors, so large doses can raise bleeding risk, especially with low vitamin K intake. NIH says the amount that matters is unknown but probably above 400 IU/day [1]. Ask your pharmacist.
Aspirin
In a large trial that found more hemorrhagic strokes with vitamin E, most participants also took aspirin, which NIH says could point to a bleeding tendency [1]. Ask your pharmacist.
Simvastatin plus niacin
An antioxidant mix (vitamins C and E, selenium, beta-carotene) blunted the rise in HDL cholesterol in people taking this combination [1]. Ask your doctor.
Chemotherapy or radiotherapy
Oncologists generally advise against antioxidant supplements during these treatments because they might reduce their effect [1]. Ask your cancer care team.
Foods that contain Vitamin E
- Wheat germ oil
- Sunflower seeds
- Almonds
- Sunflower and safflower oil
- Hazelnuts
- Peanuts and peanut butter
- Corn, soybean and rapeseed oils
- Spinach and broccoli
- Kiwifruit, mango and tomato
- Fortified cereals
Who should ask a doctor or pharmacist first
Talk to a doctor or pharmacist first if you take warfarin or another blood thinner, antiplatelet medicines or aspirin, simvastatin with niacin, or are having chemotherapy or radiotherapy [1]. Men should know the large SELECT trial found 400 IU/day of synthetic vitamin E may increase prostate cancer risk [1]. People with fat-malabsorption conditions such as Crohn's disease or cystic fibrosis should get advice on which form to use [1].
Keep Vitamin E in a routine that fits
Supin schedules what you take by time of day, reminds you, and tells you when a bottle runs low.
Vitamin E: questions people ask
Ask your doctor or pharmacist first. Large doses taken with warfarin or antiplatelet medicines can increase the risk of bleeding [1].
Clinical trials have not shown that routine vitamin E supplements prevent cardiovascular disease, and NIH says the evidence does not support taking vitamin E to prevent cancer [1].
Sources
- Vitamin E - Health Professional Fact Sheet — NIH Office of Dietary Supplements
- Vitamins and minerals: Vitamin E — NHS
Educational information, not medical advice. The amounts above are official reference values, not a recommendation for you. Check with your doctor or pharmacist before starting or changing supplements, especially if you take medication, are pregnant or have a health condition. Supin sells a subscription, not supplements. Last reviewed .