
Ingredients
and Dosages
January 1999
The
most important information on the label is the name of the dietary
supplement(s) or the product name. This indicates the key substances
contained within. However, these terms may be ambiguous. For more
information about what the name of a supplement may mean, see standard
terminology.
FDA
regulations require that the label contain a list of the specific
ingredients contained in the product. Recommended daily nutrition
intakes for some of these ingredients must also be listed.
Dosage
units
Dosage
units may be listed as
- liquid
volume (ml or milliliters, cc for cubic centimeters)
- dry
weight (kg or kilograms, mg or milligrams, g or grams)
- or
by biological assay (International Units)
An
international unit (I.U.) is a standard unit of measurement of biological
activity that is used for fat soluble vitamins (A, D and E) as well
as for some hormones, enzymes, and vaccines. It is an internationally-recognized
standard established by the International Conference for Unification
of Formulae. One I.U. represents a different amount for different
substances. The weight equivalents for fat soluble vitamins are
as follows:
Beta
Carotene
(Vitamin A) |
1
mg = 833 IU |
Vitamin
D |
2.5
mcg = 100 IU |
Vitamin
E |
1
mg = 1 IU |
Dosage
amounts
The
actual dosage amount in a dietary supplement product may be different
from the labeled amount. This is because high levels of accuracy
are costly to achieve and because the added benefits of such accuracy
are not believed to be worth the higher prices that would result.
Every
substance disintegrates, or becomes less potent, with time. Manufacturers
sometimes intentionally make substances more potent than labeled
in order to compensate for their disintegration and to give the
product a longer shelf life. This is called building in an overage.
Both the disintegration rate and the overage built in to offset
disintegration can cause further variances between a product's actual
and labeled dosage amounts.
Disintegration
can be accelerated by improper storage conditions such as exposure
to light, heat, moisture, or air. Supplements that are not properly
stored may lose potency faster than the expiration date indicates
they should.
Overages
are based on the rate that a particular substance disintegrates
and on the degree to which a variance in its dosage can be tolerated.
They are set low enough to avoid any risk of overdose, and kept
high enough to extend the product's shelf life as much as possible.
For
example, if a substance labeled to contain 200 mg. per capsule has
an allowable variance of 10%, each capsule should contain no less
than 180 mg. and no more than 220 mg. up until the labeled expiration
date assuming the product was properly stored.
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