Savvy supplement shoppers always read labels before purchasing a multivitamin, mineral, protein, or superfood supplement.
On the label, you’ll see a “Supplement Facts” box, which tells you the amount of various vitamins, minerals, macros, and other ingredients in the product based on serving size and measurements.
Those measurements are typically listed in grams (g), milligrams (mg), micrograms (mcg), or international units (IUs).
So, why are some ingredients listed in mcgs vs. mgs?
It’s all about accurate measurement of specific ingredients. Let’s explore this more.
Mcg vs. Mgs: What’s the Difference?
As you just learned, mcg stands for micrograms, and mg stands for milligrams.
These are international standards and the most common metric units of weight used to accurately measure the amounts of vitamins, minerals, herbs, and drug substances when formulated and compounded.
- A microgram is one of the smallest units in the International System of Units measurements and is used frequently in dietary supplements. It takes 1 million micrograms to make up a gram, and one thousand micrograms make up a milligram.
- A milligram is another frequently used measurement in dietary supplements for larger ingredients. It takes one thousand milligrams to make up one gram.
Every supplement formula follows a precise recipe, which is broken down using these units of weight. This helps ensure you get a safe and accurate dosage.
Why are Mcg and Mgs Used to Measure Supplements?
Most supplements will list ingredients in mcgs or mgs.
Why? Because these are the typical amounts of ingredients that fit into capsules, tablets, gummies, or liquids when dispensed.
Some supplement ingredients, such as collagen and protein powders are measured in grams due to their higher weight.
Mcg (micrograms) are used to measure amounts less than 1 milligram.
Mg amounts are used to measure amounts between 1 mg to 1,000 mgs (or 1 gram).
1,0000 mcg = 1 mg, 1,000 mg = 1 g, 1,000 g = 1 kg (kilogram)
When are Micrograms Used in Supplements?
MIcrograms are used to measure nutrients required in small amounts and/or those that can be toxic in large quantities.
Common ingredients measured in micrograms include:
- Vitamins E, D, and K
- Some B Vitamins like B12 and folate
- Micro or trace minerals like iodine, selenium, chromium
When are Milligrams Used in Supplements?
Milligrams (mg) are used to measure nutrients required in larger amounts.
Common ingredients measured in milligrams include:
- Vitamins A, C, and some B-Vitamins
- Collagen peptides
- Enzymes
- Macro minerals like calcium, magnesium, zinc, and iron
- Essential fatty acids like omega-3s, DHA, EPA, and GLA
- Amino acids (L-lysine, L-theanine, N-Acetylcysteine (NAC), etc.)
- Electrolytes
- Herbs (echinacea, elderberry, berberine, ginger, chamomile, ashwagandha, rosehips, etc.)
- DHEA
- Melatonin
- Glucosamine
- Superfoods (Spirulina, acerola cherry, dulse, cranberry, functional mushrooms, chlorella, etc.)
- Antioxidants such as bioflavonoid complexes, lutein, quercetin, astaxanthin, CoQ10, resveratrol, pycnogenol, etc.)
- Prebiotics
- Postbiotics
What about IUs and CFUs?
Let’s start with IUs, which you’ll see on Vitamin D and E labels.
IU stands for International Unit, a unit of measurement but NOT a measure of weight.
It refers to the quantity of a specific biologically active substance that produces a particular biological effect.
IU is most commonly used for medications, vaccines, and some vitamins, like vitamin D because it’s based on the potency or concentration of the substance, which varies from substance to substance.
Depending on the manufacturer, Vitamins D or E may also be listed in mcg (micrograms) or IUs.
CFU stands for colony-forming units, which measures the amount of active live active cultures in probiotic formulas.
Prebiotics and postbiotics are measured in milligrams.
What if an Ingredient Has No Measurement?
Although all vitamins and minerals must have measurements listed, other dietary supplement ingredients, such as proprietary combinations or blends of herbs or superfoods, may not list measurements for each ingredient within that blend.
Certain herbal products, such as tinctures, may not always list amounts and are not required to by law.
Proprietary formulas should list the amount of the combined formula in grams, milligrams, or micrograms.
How Do I Know the Measurements are Accurate?
Current Good Manufacturing Practices (cGMPs), as set forth by the Food and Drug Administration, dictate that supplement companies must keep records of compounding inputs and analyze and test their formulas to ensure consistent amounts of vitamins and minerals in supplements during manufacturing.
Reputable supplement companies employ advanced technology, testing, quality control, quality assurance, and manufacturing equipment to ensure their formulas are consistent from batch to bottle to capsule, tablet, gummy, or liquid serving.
These efforts and standard operating procedures (SOPs) results must be meticulously documented for review in FDA audits.
Looking for a Reputable Supplement Brand?
Country Life has been formulating and manufacturing high-quality dietary supplements, including vitamins, minerals, superfoods, antioxidants, and more, since 1971.
All our products are rigorously tested, from raw ingredients to finished supplements, to ensure a clean product and accurate potency in our NSF-GMP-certified manufacturing and distribution facilities.
Our facilities are also USDA-certified organic, and we are the first dietary supplement manufacturer to receive gluten-free certification.
We maintain our celebrated quality through extensive research, natural sourcing and accurate labeling.
Sources mentioned in this article:
- “Unit Conversions”. A US Government Initiative by the Office of Dietary Supplements and US Department of Agriculture.
- “Dietary Supplement Labeling Guide: Chapter I. General Dietary Supplement Labeling”. Food and Drug Administration.
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