Proprietary blends on supplement labels: what they actually hide

A bottle that lists "Energy Blend 1,200 mg" with ten herbs and amino acids below it is using a labeling technique called a proprietary blend. The total weight is disclosed but the individual ingredient doses are not. Under the Dietary Supplement Health and Education Act of 1994, this is legal. It is also the single most useful red flag for evaluating a supplement, because it lets manufacturers describe ingredients without committing to clinically meaningful amounts of any of them.

The legal structure that allows it

Section 101.36 of the Code of Federal Regulations requires supplement labels to list the quantity per serving of each dietary ingredient. The proprietary-blend carve-out exempts manufacturers from this requirement provided they list each component of the blend in descending order by weight and disclose a total combined weight [1]. Manufacturers historically argued that ingredient ratios are trade secrets; FDA disagreed but did not move to close the loophole [2]. The result is that products containing ten ingredients in 1,000 mg of blend can list them in any internal proportion, including the one most often used in practice: the first ingredient at 700 mg and the rest as pinch-of-dust amounts to permit listing them on the label.

How underdosing typically works

An analytical study of 67 commercially available muscle-building supplements found that, of 23 products listing creatine in a proprietary blend, only 8 contained the 3-5 g effective daily dose typically used in clinical trials, with the remainder containing 50-500 mg of creatine despite trial-style marketing language [3]. A separate analysis of 24 prebiotic supplements with proprietary fiber blends found that 18 products had inulin doses below the 3 g/day threshold associated with measurable bifidobacterial response [4]. The pattern recurs across nootropic, adaptogen, and "thyroid support" categories.

Reading a label without disclosed doses

Three practical signals matter. First, the ingredient sequence: a blend listed in descending weight order means the first ingredient is the heaviest, and most blends concentrate the bulk of mass in the first one or two ingredients. Second, the total blend weight: a 500 mg blend of ten ingredients cannot contain a 300 mg dose of any single ingredient that requires a higher trial-validated minimum. Third, the active ingredient's known clinical dose range: turmeric extracts standardized to curcuminoids require 500-1,000 mg daily of curcuminoids to match positive trials, while a 1,000 mg total blend that lists curcumin third or fourth almost certainly contains less.

What third-party certification adds

USP-Verified, NSF Certified, and ConsumerLab tested products are required by their certifiers to disclose individual ingredient doses; products with undisclosed proprietary blends cannot earn USP or NSF certification under their current programs [5]. A 2023 cross-sectional study of 1,247 sports supplements showed that proprietary-blend products had higher rates of failing third-party label-accuracy testing (32%) compared with fully disclosed labels (8%) [6].

The exception worth noting

Some standardized herbal extracts have legitimate intellectual-property concerns. Products built around clinically studied extracts such as KSM-66 ashwagandha, Sensoril ashwagandha, Theracurmin, or BCM-95 turmeric typically disclose the standardized extract dose with the trade-name extract treated as a single ingredient. This is the trial-aligned use case for a proprietary marker; it is distinct from the ten-herb blend where individual doses are deliberately obscured.

Bottom line

A proprietary blend on a supplement label is not, by itself, evidence of fraud, but it is a labeling technique that allows clinically meaningless doses to coexist with clinically suggestive marketing. When a product's marketing references a trial-validated ingredient, that ingredient should be listed with a disclosed dose, not buried in a blend. Third-party certified products and single-active-ingredient supplements avoid the issue entirely.