Proprietary blend
A proprietary blend is a group of nonnutrient dietary ingredients listed together under one name on a US supplement label, with the total weight of the blend declared but not the amount of each ingredient in it.
What it means in practice
US labeling rules let a supplement list a blend of dietary ingredients under the term "Proprietary Blend" or another descriptive term or fanciful name [2]. The ingredients in the blend must be declared in descending order of predominance by weight, and the amount shown for the blend is the total weight of those ingredients [2].
A 2023 perspective in The Journal of Nutrition, by authors from the NIH Office of Dietary Supplements, FDA and the Consumer Healthcare Products Association (a supplement and over-the-counter medicine trade association), explains the reason for the format: DSHEA allows nonnutrient dietary ingredients to be listed as proprietary blends so that companies can protect their unique formulas [1]. In the same paper, the authors note that the weight of the blend and the names of its ingredients must be declared, but not the amounts of the individual ingredients [1].
Why it matters when reading nootropics research
Trials report the amount of an ingredient that participants took. A blend label does not give that number for each ingredient. The same perspective, whose authors include one from a trade association, states that the amount of an ingredient in a proprietary blend is not available from the label "for calculating exposures in assessments of intakes or for determining doses in clinical trials" [1].
So a blend cannot be checked against the doses used in studies from the label alone. The order of ingredients shows which weighs more than which [2], but not by how much. An ingredient listed last could be present at a very small amount, and the label would look the same.
When a NootropicsWork page compares a product with doses used in studies, it uses the amounts printed on the dated label. Where a blend hides an amount, the page says the amount is not disclosed instead of estimating it.
References
- Saldanha LG, Dwyer JT, Hardy CJ, et al. Perspectives on the Use of Proprietary Blends in Dietary Supplements. J Nutr. 2023.
- Electronic Code of Federal Regulations (eCFR). 21 CFR 101.36 Nutrition labeling of dietary supplements. eCFR title 21 up to date as of 2026-11-09.