An Introduction to Doses for Vitamin E
Vitamin E dosing can be confusing, with several different forms of the vitamin and different recommendations and guidelines. This article will address some of the confusing issues concerning vitamin E dosing and will also discuss what is a reasonable dose.
Vitamin E Dosing Guidelines
Vitamin E dosing can be extremely confusing, since there are different ways to measure vitamin E content. Although current recommendations use milligrams (mg), most supplements still use international units (IU). Converting between mg and IU is not straightforward, since natural vitamin E (RRR-alpha-tocopherol, historically known as d-alpha-tocopherol) is more active than synthetic vitamin E (all-rac-alpha-tocopherol, historically known as dl-alpha-tocopherol). The synthetic form contains several different "isomers," some of which do not contribute to the daily requirement of vitamin E. As a result, it takes more dl-alpha-tocopherol than d-alpha-tocopherol (in terms of IU) to meet the daily requirements.
The Institute of Medicine (IOM) has established an RDA (recommended dietary allowance) for vitamin E (given in mg of alpha-tocopherol, a measure that takes into account only certain forms of alpha-tocopherol). Refer to the following table for RDA values for vitamin E doses, along with the conversions for IU for different forms of vitamin E:
|
Age
|
RDA (in mg of alpha-tocopherol)
|
Equivalent in IU (for d-alpha-tocopherol)
|
Equivalent in IU (for dl-alpha-tocopherol)
|
|
1 to 3 years
|
6 mg per day
|
9 IU
|
13.3 IU
|
|
4 to 8 years
|
7 mg per day
|
10.5 IU
|
15.6 IU
|
|
9 to 13 years
|
11 mg per day
|
16.5 IU
|
24.4 IU
|
|
14 years and older
|
15 mg per day
|
22.5 IU
|
33.3 IU
|
|
Pregnant women
|
15 mg per day
|
22.5 IU
|
33.3 IU
|
|
Breastfeeding women
|
19 mg per day
|
28.5 IU
|
42.2 IU
|
For nutrients that can cause toxicity, a "tolerable upper intake level" (UL) is given. This is the maximum dose that can be taken without causing significant toxicity. Refer to the following table for UL values for vitamin E dosages:
|
Age
|
UL in (in mg of alpha-tocopherol)
|
Equivalent in IU (for d-alpha-tocopherol)
|
Equivalent in IU (for dl-alpha-tocopherol)
|
|
1 to 3 years
|
200 mg per day
|
300 IU per day
|
220 IU per day
|
|
4 to 8 years
|
300 mg per day
|
450 IU per day
|
330 IU per day
|
|
9 to 13 years
|
600 mg per day
|
900 IU per day
|
660 IU per day
|
|
14 to 18 years
|
800 mg per day
|
1200 IU per day
|
880 IU per day
|
|
19 years and older
|
1000 mg per day
|
1500 IU per day
|
1100 IU per day
|
Notice that the conversion (from mg to IU) for dl-alpha-tocopherol is different when calculating RDA versus UL. This is based on the idea that only some of the forms of vitamin E in dl-alpha-tocopherol contribute to the RDA, but all forms may contribute to toxicity (for the UL calculation).
