An Introduction to Vitamin A Dosages
Vitamin A dosing can be quite confusing, since there are several different forms. This article will address some of the confusing issues concerning the proper dosage of vitamin A and will also discuss reasonable and safe dosing.
Vitamin A Dosing Guidelines
Figuring out the right dose of vitamin A can be extremely confusing, since there are different ways to measure vitamin A content. Although current recommendations use micrograms (mcg or μg), most supplements still use international units (IU). Converting between mcg and IU is not straightforward, since some forms of vitamin A are more active than others. To help compare "apples to apples," a system has been developed using retinol activity equivalents (RAE), although most supplements do not use the system.
Recommended Dietary Allowances (RDAs) for vitamin A are as follows:
|
Age
|
RDA (in terms of retinol or RAEs)
|
|
0 to 6 months*
|
400 mcg daily
|
|
7 to 12 months*
|
500 mcg daily
|
|
1 to 3 years
|
300 mcg daily
|
|
4 to 8 years
|
400 mcg daily
|
|
9 to 13 years
|
600 mcg daily
|
|
14 years and older (women)
|
700 mcg daily
|
|
14 years and older (men)
|
900 mcg daily
|
|
Pregnant women (14 to 18 years old)
|
750 mcg daily
|
|
Pregnant women (19 years and older)
|
770 mcg daily
|
|
Breastfeeding women (14 to 18 years old)
|
1200 mcg daily
|
|
Breastfeeding women (19 years and older)
|
1300 mcg daily
|
*RDAs are not established for vitamin A for infants under one year old; instead, an "Adequate Intake" level is provided.
For nutrients that can cause toxicity, a "Tolerable Upper Intake Level" (UL) is given. This is the maximum that can be taken (from all sources, including the diet) without causing significant toxicity. Refer to the following table for UL values for vitamin A:
|
Age
|
UL (in terms of retinol or RAEs)
|
|
0 to 3 years
|
600 mcg daily
|
|
4 to 8 years
|
900 mcg daily
|
|
9 to 13 years
|
1700 mcg daily
|
|
14 to 18 years
|
2800 mcg daily
|
|
19 years and older
|
3000 mcg daily
|
