How to Read a Supplement Label

by Melissa Chichester

Ever-evolving label and packaging changes on supplements can make reading labels confusing.

There is a lot to take into consideration, including the daily value percentage, how much to consume per serving, where your supplement is manufactured, and what the supplement does for the body. There are key identifiers on every label that reveal useful clues about your supplement.

International Units (IU), Milligrams (mg), and Micrograms (mcg)

Fat-soluble vitamins, including Vitamins A, D, and E, are measured in mg (milligrams) or mcg (micrograms). Water-soluble vitamins, including C vitamins and the B-complex group, are also measured in milligrams (mg) or micrograms (mcg). One milligram is the equivalent of 1000 micrograms.

You might be wondering how to convert mcg to iu. As an example, here’s how to convert mcg to iu for Vitamin A

All you have to do is multiply the IU of Vitamin A by 0.3 to get the value as mcg.

Puritan’s Pride Vitamin A contains 8,000 IU – when multiplied by .3, you get 2,400 mcg. 

So how do we do the reverse? Let’s convert 125 mcg to iu with Vitamin D. 

All you have to do is divide 125 by .025 – and you will see that equals 5,000 IU – just like our label reads. 

For more conversions, visit the Dietary Supplement Ingredient Database.

Retinol Activity Equivalents (RAE)

You may also see “mcg RAE” on certain labels, such as Vitamin A. RAE stands for “retinol activity equivalents.” 

According to the National Institutes of Health Office of Dietary Supplements, RAEs “account for the different bioactivities of retinol and provitamin A carotenoids, all of which are converted by the body into retinol. 

Percent Daily Value

Percent Daily Value (DV) tells what percentage of the recommended daily intake for each nutrient depends on the age group. For foods that have an established Daily Value, the FDA permits claims called “Nutrient Content” claims, which are statements made to characterize the levels of any particular nutrients within food or supplement. A symbol under the “Percent Daily Value” column and corresponding footnote indicates that a Daily Value is not established for that dietary ingredient.


The list of all ingredients includes nutrients and other ingredients used to formulate the supplement, in decreasing order by weight. What ingredients are listed first are the most abundant in the product. Some products also contain proprietary blends that do not disclose the amount of each nutrient but are listed in order of predominance too. The use of proprietary blends helps deliver unique products to our customers. 

If ingredients are present in quantities of less than 2%, they do not need to be listed in order of predominance.

In this case, the statement “Contains less than 2% of:” is sufficient. These ingredients are considered inactive but play an important role in a formulation that serves a technical function.

Suggested Use

This section instructs the buyer on how the supplement should be taken. This includes if it needs to be taken with a meal or even the time of day in which something should be taken.

Manufacturer Name

The manufacturer’s or distributor’s name and place of business or phone number are required to appear on the label. If you are curious about where a product is manufactured or to know more about the company, check to see if they have a website with more information.


Generally speaking, most supplements should be stored at room temperature in their original containers, out of the reach of children, and should be used before the expiration date. This is important to ensure the potency of ingredients in the supplement.

Actual Size

Many supplement bottles will have an icon that shows the actual size of the supplement, so you can determine whether or not it is something you can handle.

Certified Labels

Some supplement labels will include certified, distinguishing icons or seals appearing on labels. This may include USDA Organic, Leaping Bunny, Certified Gluten-Free, and Kosher icons or seals. If you are seeking out these features, look for their identifying features on the bottle.