How to Read a Supplement Label: Supplement Facts, % Daily Value and Seals

A supplement label packs a lot into a small space: a product name, a Supplement Facts panel, a list of other ingredients, directions, warnings and often a few seals. Once you know what each part is required to show, and what it is not required to show, comparing two bottles gets much quicker.

The short version: start with the serving size, read the amount and the % Daily Value for each ingredient, scan the other ingredients for allergens and sweeteners, and treat seals as a check on quality, not on whether the product works. This guide walks through each part with examples from supplements in our catalog.

How we wrote this: the rules below come from the FDA, the federal labeling regulation and the NIH Office of Dietary Supplements, linked in each section. Product examples use the published label facts on each product page. We have not tested these products.

What every supplement label must show

The FDA lists five required parts: the product name with a statement that it is a dietary supplement, the name and place of business of the maker, packer or distributor, a Supplement Facts panel, a list of other ingredients not declared in that panel, and the net quantity of contents.

One thing a label cannot tell you is that the product was approved before sale. The FDA does not approve dietary supplements before they reach shoppers; the company is responsible for the safety of the product and the accuracy of its claims.

Reading the Supplement Facts panel

Serving size comes first

Every amount in the panel is per serving, and a serving can be one capsule, two soft gels or one scoop. The FDA requires the panel to show the serving size and the amount of each dietary ingredient per serving. When you compare two products, check whether one needs two units to match a single unit of the other. Nordic Naturals Ultimate Omega, for example, lists its omega-3 amounts for a two soft gel serving.

Amount per serving and the units used

Amounts appear in grams (g), milligrams (mg) or micrograms (mcg). A microgram is a thousandth of a milligram, so a large number in mcg can be a small amount by weight. Under the federal rule for supplement labels, 21 CFR 101.36, vitamin D must be declared in mcg and may also be shown in International Units (IU). That is why Nordic Naturals Vitamin D3 lists 25 mcg (1,000 IU) per soft gel, and the Ritual Essential for Women 18+ multivitamin lists 50 mcg (2000 IU) per capsule. Our vitamin D3 label guide walks through both labels line by line.

Some nutrients use special units. Folate, for instance, appears as mcg DFE on the Ritual label, so compare folate between products only when both use the same unit. For a worked example with a mineral, see our guide to reading the form and elemental amount on a magnesium label.

% Daily Value

The Daily Value is the reference amount of a nutrient to consume, or not exceed, each day, and the % Daily Value shows how much one serving contributes, according to the FDA. The same agency’s rule of thumb: 5% DV or less is low and 20% DV or more is high. Supplement Facts panels use the same Daily Values as food labels.

A number above 100% is common on single-nutrient products. The Nordic Naturals D3 label lists 125% of the Daily Value per soft gel. A high %DV is not a warning by itself, but it is a good reason to add up what you get from every product you take, and to ask your doctor about dose. Thorne Vitamin B12, with 1,000 mcg per capsule, is the kind of label worth that conversation. Our vitamin B12 label guide reads that panel line by line.

The asterisk: “Daily Value not established”

Many supplement ingredients, such as creatine, omega-3s or probiotics, have no Daily Value. The federal labeling rule requires a symbol, usually an asterisk, in the %DV column for these, matched by the note “Daily Value not established” at the bottom of the panel. An asterisk does not mean the amount is too high or too low; there is simply no reference number to compare it with. Fish oil is a common case: our fish oil label guide shows how EPA, DHA and the fish oil amount are listed.

Proprietary blends

A proprietary blend groups several ingredients under one name. Under 21 CFR 101.36, the label must give the total weight of the blend and list its ingredients in descending order by weight, but it does not have to show the amount of each one. If a specific ingredient matters to you, a blend makes it hard to know how much you get; single-ingredient products such as Momentous Creatine and Thorne Creatine, which each list 5 g of creatine monohydrate per scoop, avoid that question.

Probiotics and CFU

Probiotic amounts are often shown in colony forming units (CFU), which count viable cells, according to the NIH Office of Dietary Supplements. The same fact sheet notes that the required Supplement Facts amount is the total weight of the microorganisms, and that listing CFU is voluntary. Culturelle Digestive Daily Probiotic lists 10 billion CFU of one strain, Lactobacillus rhamnosus GG, per capsule, while Amazing Grass Super Greens lists 1 billion CFU per scoop within a greens formula. Compare the strain names as well as the count. Our probiotic label guide covers CFU timing, strain names and storage in more detail.

Other ingredients, allergens and sweeteners

Below the panel sits the list of other ingredients: capsule shells, fillers, flow agents, flavors and sweeteners. This is where you find out whether a capsule is gelatin or plant based, and whether a powder is sweetened. Thorne Magnesium Bisglycinate lists citric acid and monk fruit concentrate as its other ingredients, and the Culturelle capsule is vegetarian (hypromellose).

Read the allergen and “free from” lines here too. Fish oils such as Carlson The Very Finest Fish Oil contain fish, and a free-from line (gluten, dairy, soy) is a brand statement you can match against your own needs. If you avoid animal products, our vegan supplements and protein powders list checks those claims for you.

Claims and the FDA disclaimer

Labels may describe how a nutrient affects the body’s structure or function. When they do, the FDA requires a disclaimer saying the statement has not been evaluated by the agency and that the product is not intended to diagnose, treat, cure or prevent any disease. Seeing that line means the claim is the company’s own wording.

Third-party seals: what they do and do not mean

Independent programs test some supplements and let them carry a mark. The NIH Office of Dietary Supplements names ConsumerLab.com, NSF International and USP among them, and explains that a seal shows the product was properly made, contains the listed ingredients and is free of harmful levels of contaminants. A seal does not mean the product is safe for you or that it works.

NSF Certified for Sport goes a step further for athletes: NSF says it screens for substances banned by major athletic organizations, checks that contents match the label and contaminants are not at unsafe levels, and audits the facility. The same NSF page explains how to search its certified product list. In our catalog, Momentous Creatine, Thorne Creatine and Thorne Magnesium Bisglycinate list NSF Certified for Sport, while the Ritual multivitamin lists USP Verified.

Check the exact product, not just the brand. Thorne Zinc Picolinate 30 mg is a useful example: the version on our page is not NSF Certified for Sport, and Thorne sells the certified one separately. Our zinc supplement label guide reads that bottle’s panel line by line. Our third party tested supplements list gathers products whose marks we could confirm.

Warnings, directions and Proposition 65

The directions and cautions section tells you how much to take and who should check with a doctor first. The Thorne Magnesium Bisglycinate product page, for example, notes that gas, bloating or diarrhea may occur in some people taking magnesium; read these lines before you change the dose.

Products sold in California may carry a Proposition 65 warning, as the Ritual Essential Protein label does for lead. The state’s Proposition 65 warnings site explains what these warnings mean, and it is worth a read before you decide.

Look up a label before you buy

The Dietary Supplement Label Database from the NIH Office of Dietary Supplements lets you search full label information by brand, product or ingredient, which helps when the store photo is too small to read. Pair it with the certified product search on the NSF site if a seal matters to you.

A quick label checklist

• Serving size: how many capsules, soft gels or scoops?
• Amount per serving, in the same unit as the product you compare it with
• % Daily Value, and an asterisk where no DV exists
• Proprietary blend: total weight only, or individual amounts?
• Other ingredients: capsule type, sweeteners, flavors, allergens
• Seals: which program, and does it cover this exact product?
• Directions and warnings, including any Proposition 65 notice

FAQ

What is the difference between Supplement Facts and Nutrition Facts?

Supplement Facts is the panel used on dietary supplements; Nutrition Facts is the panel on conventional foods. Both use the same Daily Values, per the FDA. For the food panel, see our guide to reading a Nutrition Facts label. For the protein, added sugars, sugar alcohol and fiber lines on a bar, see our protein bar label guide. For a fiber powder sold with a Nutrition Facts panel, see our psyllium husk label guide.

Is more than 100% Daily Value too much?

Not automatically. It means one serving gives more than the reference amount. Add up every product you take and ask your doctor or pharmacist whether the total suits you.

Why does my label show both mcg and IU for vitamin D?

The federal rule requires mcg and allows IU as an extra declaration, so many labels show both, as the Nordic Naturals D3 label does with 25 mcg (1,000 IU).

Does a USP or NSF seal mean a supplement is safe?

No. According to the NIH Office of Dietary Supplements, a seal points to manufacturing quality and label accuracy, not safety or effectiveness.

Should I talk to my doctor before taking a supplement?

Yes. Talk to your doctor before starting a new supplement, especially if you are pregnant or nursing, take medicine or have a health condition. For help choosing between products, see our supplements buying guide, and for powders, the protein powder buying guide.

Ready to compare? Browse the supplements and protein collections with this checklist in hand.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.