What is Mcg in Vitamins? Guide to Vitamin Labels

If you've ever checked a vitamin or mineral supplement label, you've probably seen these three letters: mcg. Either on the front of the label or within the Supplement Facts panel, next to an ingredient like Vitamin D3, you'll see, for example, "50 mcg." It's clearly some measurement, but what does it stand for, and how much is a mcg unit exactly?

Understanding how vitamins or minerals are measured can help you understand how much of a certain nutrient you are taking – a key consideration for anyone looking to make informed choices when it comes to their supplement routine. Now, let's break down exactly what a microgram is.

Understanding Mcg in the Context of Vitamins

What is mcg in vitamins? “Mcg” means microgram, which, as you might guess from the name, is tiny! But just how small? You may be more familiar with a gram, a standard unit of mass measurement in the metric system. A common point of comparison for 1 gram is a small paper clip. That's already pretty small. A microgram is one millionth of a gram! Imagine a paper clip one million times lighter than the one in your desk drawer. That's hard to imagine and probably wouldn't be too helpful for collecting paper!

Vitamins and minerals interact with our cells, and the cells in our body are microscopic, so the amount our bodies need and the doses in supplements must be measured on that tiny scale, too!

Some vitamins and minerals are measured in “mg,” which stands for milligram. A milligram is another standard, metric unit of mass, but it’s bigger than a microgram; in fact, it’s exactly 1000 times bigger than a microgram. Some nutrients, like Vitamin C, are measured in milligrams.

When you're looking at the back label, right next to the amount in mcg units, you'll sometimes see another unit of measurement, "IU." Now that you know what a microgram is, what's an IU? IU stands for "International Unit." That name is a lot less obvious than a microgram, but it's defined as "quantity of a substance ... that produces a specified effect when tested according to an internationally accepted biological procedure."[1]

While mcg and mg are units of mass that measure the physical amount of each substance, IUs measure the biological effect of a specific dose of vitamin. The IU measurement is unique for each vitamin, measuring how much activity that specific substance has for a given amount. For example, one mcg of Vitamin D is equal to 40 IU of Vitamin D. That doesn't mean that one mcg of Vitamin C also equals 40 IU of Vitamin C (because it doesn't); it just means that one microgram of Vitamin D has the potency of 40 International Units of Vitamin D. IUs are mostly used to measure fat-soluble vitamins, like Vitamin A, Vitamin D and Vitamin E. However, measurements of mass like micrograms can be easier to understand from a consumer perspective, so new labeling regulations require products to include the amount in mcg in addition to IU.

Importance of Dosage in Vitamin Supplements

Because it is recommended that we consume certain amounts of different nutrients depending on things like our age, gender, and life stage, it's essential to understand the dose, or how much, of a certain vitamin or mineral is in each supplement you take. When taking a multivitamin, reading the label can help you know how much of each nutrient is in each serving. If you have ever wondered the difference between a multivitamin vs individual vitamins, this guide can help you out!

The Food & Drug Administration regulates the supplement industry to ensure safety. The United States Pharmacopeia verifies many Nature Made® products, which tests and verifies the ingredients, potency, and manufacturing process. If your primary health provider has suggested you supplement your vitamin intake, follow their guidance when selecting the dosage to add to your supplement routine. Here are some tips on how to read the label!

How to Read and Interpret Vitamin & Supplement Labels 

Looking at the label on your vitamins or supplements, you'll want to focus on a few key areas to find pertinent information.

Suggested Use

The first place to look is "Suggested Use." These are instructions on how and when to take the supplement. Always follow the suggested use when you take your supplements.

Serving Size

Under "Supplement Facts," in the big white box, you'll find the "Serving Size." The serving size tells you the number of Tablets/Softgels/Gummies to take daily.

Amount Per Serving

The "Amount Per Serving" tells you how much of each ingredient is included in each serving. If the serving size is two tablets, then the amount listed for each ingredient is for every two tablets.

Percent Daily Value

To the right of "Amount Per Serving" is "% Daily Value." The percent daily value is how much of this ingredient is included in the serving compared to the RDA (Recommended Dietary Allowance). Recommended Dietary Allowances are the "Average daily level of intake sufficient to meet the nutrient requirements of nearly all (97–98%) healthy individuals."[2]

Tailoring Vitamin Intake to Individual Needs

Everyone's needs are different; this is true in many things in life, and it's true for vitamin intake as well! Depending on your age, gender, diet, location, and more, your specific nutrient needs will vary! You may need more of one nutrient or less of another, so it's crucial to read the label when you pick your supplements to make an informed choice. It's always best to consult with your primary care provider or another medical professional when starting a supplement routine to get advice tailored directly to you.

Nature Made®'s Commitment to Accurate Labeling and Quality

Nature Made® is committed to clear and accurate labeling following FDA regulations so that  consumers can easily read the label, know what each supplement contains, and make an informed decision. With safety for our consumers as our #1 goal, we understand the importance of clear communication and want you to know the high-quality product you find on your pharmacy shelf! Team Nature Made® is dedicated to consumer education, helping you make the right choice for you.

Making Informed Choices with Nature Made®

So, now that you understand what a mcg is (a microgram), what IU means (the amount of biologically active substance in a given amount), and how to read the back label, you're set to make an informed decision on what vitamins, minerals and supplements may be right for you. Nature Made® is the #1 Pharmacist Recommended Vitamin & Supplement Brand.*

*Based on a survey of pharmacists who recommend branded vitamins and supplements.

This information is only for educational purposes and is not medical advice or intended as a recommendation of any specific products. Consult your health care provider for more information.

References

1. Britannica, T. Editors of Encyclopaedia (2023, March 20). International Unit. Encyclopedia Britannica. https://www.britannica.com/science/International-Unit
2. National Institute of Health. Nutrient Recommendations and Databases. ods.od.nih.gov. Published 2019. https://ods.od.nih.gov/HealthInformation/nutrientrecommendations.aspx