Dietary Supplement Ingridient Database

Unit Conversions

In May 2016, the U.S. Food and Drug Administration (FDA) announced regulations that require amendments to the existing supplement facts label, which uses units and conversions based on the 1968 Recommended Daily Allowances (RDA). The new regulations will be mandatory in 2019-2020. Voluntary compliance prior to that date is permitted, and it is expected that there will be a period of time when both types of labels will be on the market.

The changes that will affect the application of DSID results are the changes in the units used to declare vitamins and minerals on supplement labels. The FDA will permit manufacturers to include the amounts of nutrients in the old units in parentheses adjacent to the amounts in the new units. For more information from the FDA, click here.

Nutrient Current DV Unit* Current Conversion* New DV Unit (required by 2019-2020) New Conversion (required by 2019-2020)
Vitamin A IU 1 IU = 0.3 mcg retinol
1 IU = 0.6 mcg beta-carotene
mcg RAE 1 mcg RAE = 1 mcg retinol
1 mcg RAE = 2 mcg supplemental beta-carotene
1 mcg RAE = 12 mcg beta-carotene
1 mcg RAE = 24 mcg alpha-carotene
1 mcg RAE = 24 mcg beta-cryptoxanthin
Vitamin E IU 1 IU = 0.67 mg for d-alpha-tocopherol (natural)
1 IU = 0.9 mg for dl-alpha-tocopherol (synthetic)
mg alpha-tocopherol 1 mg vitamin E (as alpha-tocopherol) label claim = 1 mg of natural α-tocopherol
1 mg vitamin E (as alpha-tocopherol) label claim = 2 mg of synthetic α-tocopherol
Vitamin D IU 1 IU = 0.025 mcg mcg 1 IU = 0.025 mcg
Folate mcg mcg DFE 1 mcg DFE = 1 mcg folates
1 mcg DFE = 0.6 mcg folic acid
Niacin mg mg NE 1 mg NE = 1 mg niacinamide
1 mg NE = 1 mg inositol hexanicotinate
1 mg NE = 1 mg niacin
1 mg NE = 60 mg tryptophan

*The data in the DSID-4 are reported using the current FDA ingredient unit labeling.

Labeling Units of Measure

mcg: microgram. One millionth of one gram.
mg: milligram. One thousandth of one gram.
IU: International Unit is a measure of biological activity and is different for each substance.
RAE: Retinol Activity Equivalent.
DFE: Dietary Folate Equivalent
NE: Niacin Equivalent.

Vitamin A

Vitamin A in the diet can come in different forms: retinol, beta-carotene, alpha-carotene, and beta-cryptoxanthin. Some of these forms have greater bioavailability than others. Vitamin A has previously been reported in international units (IU). New labeling guidelines require reporting of vitamin A in the unit of mcg RAE, (retinol activity equivalent) in order to account for the differing bioavailability of the forms. To convert from IU to RAE, use the 2 steps listed in the table, above.

Vitamin E

New guidelines require that Vitamin E content be determined based on the source of vitamin E and that it be reported as mg alpha-tocopherol rather than in IU. Vitamin E in food and dietary supplements can come from natural or synthetic forms. To convert from IU to mg alpha-tocopherol, use the 2 steps listed in the table, above.

Vitamin D

New guidelines require that vitamin D be reported in mcg rather than IU.


Dietary folate can come in different forms; naturally occurring folates and synthetic folic acid. Previously all folates and folic acid were reported as mcg folic acid. New guidelines require that folates/folic acid be reported in Dietary Folate Equivalents (DFE) with mcg of folic acid in parentheses. Folic acid has greater bioavailability than naturally occurring folates.


New guidelines require that niacin be reported as Niacin Equivalents (NE). Dietary niacin can come in several forms, and the new unit accounts for tryptophan as a source of niacin.

Dietary Supplement Ingridient Database