A proprietary blend on a supplement label bundles several ingredients under a single name, with one total weight for the whole bundle. The label does not have to give the weight of each ingredient inside it. This guide shows what you can and cannot learn from that panel.
What the law asks the label to show
US rules for dietary supplement labels sit in 21 CFR 101.36. They say a blend may carry the name "Proprietary Blend" or a fanciful name of the maker's choosing. The blend name sits on one line of the Supplement Facts panel. On that same line, in the amount column, the label must show the total weight of all the ingredients in the blend.
Under that line, the ingredients are listed in a column or a row, indented. They must appear in descending order of predominance by weight. So the ingredient that weighs the most is named first, and the one that weighs the least is named last.
Sources: 21 CFR 101.36(c), Cornell Legal Information Institute copy of the Code of Federal Regulations; FDA, Dietary Supplement Labeling Guide, Chapter IV, Nutrition Labeling.
What the total weight tells you
The total is the weight of everything in the blend added together. Say a blend line reads 600 mg and lists five ingredients. Those five ingredients share 600 mg. No single one can weigh more than the whole.
That total also puts a ceiling on each part. If one ingredient is a name you care about, you know its weight is under the blend total. You can compare that ceiling with the amount shown for a product that lists the same ingredient on its own line.
The total also helps you compare products. Two blends that list the same ingredients can have very different totals. A bigger total does not prove a better product, but a tiny total shared by many ingredients means each one is present in a small amount.
Sources: FDA, Dietary Supplement Labeling Guide, Chapter IV; 21 CFR 101.36(c).
What the order of ingredients tells you
Order is the second clue. Because the list runs from heaviest to lightest, the first name makes up more of the blend than the second, and the second more than the third. Most of the total is usually in the first few names.
The order does not tell you how much heavier one is than the next. The first ingredient could be 90 percent of the blend or 25 percent. A name near the end of the list could be a trace amount. A long list with one famous ingredient at the bottom is worth a second look.
Read the order as a ranking, not a measurement. It narrows the guess. It does not replace a number.
Sources: 21 CFR 101.36(c); FDA, Dietary Supplement Labeling Guide, Chapter IV.
What a proprietary blend does not have to show
The FDA labeling guide says the individual weight of each ingredient in the blend is not required when the ingredient has no Daily Value. Those ingredients carry a symbol that points to the note "Daily Value not established." So the panel can hide the split inside the blend.
There is one important exception. A dietary ingredient that has a Reference Daily Intake or Daily Reference Value must be listed on its own line with its weight. Vitamin C is one example. If a vitamin or mineral with a Daily Value is inside a blend, the rule asks for it to be declared separately.
Notice what is missing. No rule in these pages asks a maker to prove the amounts to the buyer. The label states a total and an order. Whether the real product matches the label is a different question, and a label cannot answer it.
Sources: FDA, Dietary Supplement Labeling Guide, Chapter IV; 21 CFR 101.36(b)(2) and (c).
A short checklist for reading one
Use these steps when a label shows a blend. They take about a minute.
- Find the blend line and read its total weight.
- Count the ingredients under it. Divide the total by that count for a rough average share.
- Read the order. Note which names sit first and which sit last.
- Check whether any ingredient with a Daily Value is listed on its own line, as the rule asks.
- Compare the total with a similar product that lists each ingredient by weight.
- Look for a third-party test report, since only a test can tell you what is in a given lot.
The average in step two is only a rough guide. Real shares are uneven, because the order runs from most to least. Treat it as a way to spot a long list sharing a small total, not as the true amount of any one ingredient.
This is general information, not medical advice. Before you start a blend product, ask a pharmacist to check it against any prescriptions you use, and ask your doctor if a condition could be affected.
Sources: FDA, Dietary Supplement Labeling Guide, Chapter IV.
Sources
- 21 CFR 101.36, Nutrition labeling of dietary supplements: https://www.law.cornell.edu/cfr/text/21/101.36
- FDA, Dietary Supplement Labeling Guide, Chapter IV, Nutrition Labeling: https://www.fda.gov/food/dietary-supplements-guidance-documents-regulatory-information/dietary-supplement-labeling-guide-chapter-iv-nutrition-labeling