How to Read a Supplement Facts Label (and Spot a Proprietary Blend)

To read a supplement label, start with the serving size, then check the dose of each active ingredient against the amount research supports, and be wary of any "proprietary blend" that hides individual doses. The Supplement Facts panel tells you almost everything you need to judge a product. The front of the tub mostly tells you what the brand wants you to believe.

This guide walks through the panel line by line, explains how proprietary blends work, and finishes with a checklist you can use in the store or on a product page.

Where to Look: The Supplement Facts Panel

Every dietary supplement sold in the US must carry a Supplement Facts panel. The FDA sets what goes in it and how it's laid out (FDA Dietary Supplement Labeling Guide). Ignore the front of the package for now: words like "clinical", "advanced" and "max strength" have no legal definition.

Here's a simplified example of a pre-workout panel, so you can see each part:

Step 1: Check the Serving Size First

Every amount on the panel is per serving, and a serving isn't always one scoop or one capsule. A multivitamin might be two capsules; a protein powder might be two scoops. Two things to check:

• How many units make one serving. A "1,000 mg" capsule product with a three-capsule serving is really 333 mg per capsule.
• Servings per container. This is how you work out what a product really costs. Divide the price by the number of servings, and compare cost per serving, not cost per tub.

Step 2: Compare Each Dose With What Research Supports

This is where most products win or lose. An ingredient only does something if there's enough of it. Some common examples:

The 400 mg caffeine limit comes from the FDA's caffeine guidance. If a pre-workout lists a long ingredient list but only 1 g of citrulline, it's relying on the ingredient's name, not its effect. Our ranking of clean pre-workout powders only includes products with fully listed doses.

Step 3: Look at the Form ("as …")

Many ingredients come in different forms, and the panel tells you which one in brackets, for example "Magnesium (as magnesium glycinate)" or "Vitamin B12 (as methylcobalamin)". Forms matter for two reasons:

• Absorption and tolerance. Some forms are absorbed better or are easier on the stomach. Magnesium oxide, for example, is cheap and well known for causing loose stools at higher doses.
• The evidence. For creatine, monohydrate has hundreds of studies behind it. Pricier forms like HCl don't have better evidence, as our creatine monohydrate vs HCl comparison explains.

For minerals, the amount listed is the mineral itself (the "elemental" amount), not the weight of the whole compound.

Step 4: Read %DV Carefully

The % Daily Value column shows how much of a day's recommended amount one serving provides. Two things to know:

• A dagger (†) or asterisk means no Daily Value exists. That's normal for creatine, caffeine, amino acids and herbs. It doesn't mean the dose is good or bad.
• More than 100% isn't automatically better. Water-soluble vitamins like B12 are often listed at 1,000% or more and are generally harmless at those levels. But some nutrients, such as vitamin A, iron and zinc, have upper limits, so very high %DVs in a multivitamin plus a separate supplement can add up. The NIH Office of Dietary Supplements lists upper limits in its fact sheets.

Step 5: Spot a Proprietary Blend

A proprietary blend is a group of ingredients listed under one name, often something like "Pump Matrix" or "Energy Complex", with one total weight for the whole blend and no individual doses. It looks like this:

What the rules require

Under FDA rules, a proprietary blend must show the blend's name, its total weight per serving, and the ingredients inside it, listed in descending order by weight. Individual amounts aren't required (21 CFR 101.36).

Why that's a problem

• You can't tell if any ingredient is at an effective dose. In the example above, the whole blend is 4.2 g. That's less than the 6 g of citrulline research uses on its own, and it has to fit five more ingredients too.
• You can't tell how much caffeine or other stimulant you're taking. That matters if you also drink coffee or are sensitive to stimulants.
• You can't compare products. Two blends with the same ingredients can have very different amounts of each.

How to read one anyway

Use the descending-order rule. The first ingredient is the largest, and each one after it is the same or smaller. If the blend's total weight is small and the first ingredient is a cheap filler, the ingredients further down are likely tiny amounts.

Our rule: if a product hides its doses behind a blend, skip it unless you have a strong reason to trust the brand. Plenty of good products list every dose.

Step 6: Read the "Other Ingredients"

Below the panel is the list of other ingredients: fillers, flavors, sweeteners, colors and capsule materials. Most are harmless, but it's where you'll find:

• Sweeteners (sucralose, acesulfame K, stevia, sugar alcohols), useful to know if they upset your stomach.
• Artificial colors, which some people prefer to avoid.
• Allergens, such as milk, soy or gluten. Check the separate "Contains" statement too.

Protein powders: watch for amino spiking

Some protein powders have been caught adding cheap amino acids like glycine or taurine, which raise the measured protein content without adding useful protein. If you see free amino acids listed alongside the protein, check that the protein grams per scoop still make sense. Third-party testing is the best protection, which is why our cleanest protein powders favors tested brands.

Step 7: Understand the Claims and the Disclaimer

You'll usually see a box with this text: "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."

That disclaimer is required whenever a product makes a structure/function claim, such as "supports muscle recovery" or "supports immune health". It means the FDA hasn't reviewed the claim. Supplements don't need FDA approval before they're sold, so claims like "clinically proven" are only as good as the study behind them, if there is one.

Step 8: Look for a Third-Party Seal

The label can't tell you whether the product actually contains what it lists. Independent testing can. Look for:

• NSF Certified for Sport: tests for label accuracy, contaminants and hundreds of substances banned in sport.
• Informed Sport or Informed Choice: tests for banned substances.
• USP Verified: checks identity, strength, purity and manufacturing.

A seal isn't required, and some good brands publish their own lab reports instead. But "lab tested" printed on the tub, with no report or certifier named, doesn't count. Creatine gummies show why this matters: in independent tests, many contained far less creatine than labeled.

Your Label-Reading Checklist

1. Serving size: how many scoops or capsules, and how many servings per container?
2. Doses: is each main ingredient at a dose research supports?
3. Forms: are the forms well absorbed and backed by evidence?
4. %DV: are any nutrients well over their upper limit, especially if you take other supplements?
5. Proprietary blends: are any doses hidden? If so, is there a good reason to trust the brand?
6. Other ingredients: any sweeteners, colors or allergens you want to avoid?
7. Claims: do bold claims link to real research?
8. Testing: is there a third-party seal or a published lab report?

FAQ

Are proprietary blends illegal?

No. They're legal as long as the blend lists its total weight and its ingredients in descending order by weight. The problem is that you can't see how much of each ingredient you're getting.

Does a Supplement Facts label mean the FDA approved the product?

No. The FDA sets the labeling rules, but supplements don't need FDA approval before they're sold. Brands are responsible for making sure their products are safe and accurately labeled.

Why do some vitamins show over 1,000% of the Daily Value?

Some vitamins, especially B12, are poorly absorbed in large doses, so brands often include far more than 100%. For water-soluble vitamins that's generally harmless. For nutrients with upper limits, such as vitamin A, iron and zinc, check the total across all your supplements.

What's the difference between Supplement Facts and Nutrition Facts?

Supplement Facts is used on dietary supplements and can list ingredients without a Daily Value, like creatine or herbs, plus their forms and plant parts. Nutrition Facts is used on regular foods. Some protein bars and drinks are sold as foods, so they use Nutrition Facts instead.

Where can I look up a supplement's label before buying?

The NIH's Dietary Supplement Label Database lets you search the labels of thousands of US products, which is handy for comparing products side by side.

The Bottom Line

Skip the front of the tub and go straight to the Supplement Facts panel. Check the serving size, compare each dose with what research supports, look at the forms, and treat proprietary blends as a reason to look elsewhere. Then look for a third-party seal to make sure the label is telling the truth. It's the same process we use for every product we review; read more about how we evaluate supplements.