Proprietary Blends Explained: How to Read a Hidden-Dose Label
A single number for several ingredients is legal on a supplement label. It also hides the number you most need. Here is how to read one.
What a proprietary blend is
U.S. labeling rules let a supplement list a group of ingredients under one name, with the total weight of the group and the ingredients in descending order by weight, but without individual amounts. Companies argue this protects their formulas. The FDA does not approve labels before sale[4], and manufacturers must still follow manufacturing and labeling rules[3].
A worked example
Melonex lists "Proprietary Blend 500 mg" containing L-citrulline DL-malate, L-arginine alpha-ketoglutarate and L-arginine HCl. From this you can tell that citrulline malate is the largest part and that the total is 500 mg. You cannot tell whether the capsule holds 400 mg of citrulline malate and 50 mg of each arginine, or a third of each.
Estimating the ceiling
Even without the split, the total sets an upper limit. If every milligram were the most important ingredient, how would it compare with research? For Melonex, the whole blend at the label maximum is 1 gram a day, against 3 to 6 grams of citrulline[2] or 4 to 24 grams of arginine[1] in trials. That comparison answers the most important question even when the label does not.
Watch the salt weight
Many ingredients are listed as salts or complexes: citrulline malate, arginine HCl, magnesium citrate. The listed weight includes the partner molecule. Citrulline malate 2:1 is about two thirds citrulline; arginine alpha-ketoglutarate is about half arginine. Real amino-acid content is always lower than the listed weight.
Questions to send the company
- How many milligrams of each blend ingredient are in one serving?
- For salts, what is the ratio (for example, citrulline to malate)?
- Can you send the certificate of analysis for my lot?
Transparent companies answer. The reply, or the lack of one, is useful information.
When blends meet marketing
A blend becomes a problem when the sales page describes each ingredient's benefits in detail while the label hides whether there is enough of it to matter. Advertising claims are expected to be truthful and substantiated, including claims made through testimonials[5]. If a page promises "optimal dosage" but the label will not say what the dose is, trust the label.
Sources for this page
Every entry links to the original record. The trials used single amino acids, usually at several grams a day; none of them tested the Melonex capsule.
- 1Dong JY, Qin LQ, Zhang Z, et al. Effect of oral L-arginine supplementation on blood pressure: a meta-analysis of randomized, double-blind, placebo-controlled trials. Am Heart J. 2011;162(6):959-965. pubmed.ncbi.nlm.nih.gov/22137067/
- 2Khalaf D, Kruger M, Wehland M, Infanger M, Grimm D. The effects of oral L-arginine and L-citrulline supplementation on blood pressure. Nutrients. 2019;11(7):1679. pubmed.ncbi.nlm.nih.gov/31336573/
- 3Electronic Code of Federal Regulations. 21 CFR Part 111: Current Good Manufacturing Practice in Manufacturing, Packaging, Labeling, or Holding Operations for Dietary Supplements. www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-111
- 4U.S. Food and Drug Administration. Questions and Answers on Dietary Supplements. www.fda.gov/food/information-consumers-using-dietary-supplements/questions-and-answers-dietary-supplements
- 5Electronic Code of Federal Regulations. 16 CFR Part 255: Guides Concerning the Use of Endorsements and Testimonials in Advertising. www.ecfr.gov/current/title-16/chapter-I/subchapter-B/part-255
Ready to run a fair 60-day Melonex trial?
Orders finish on the maker's BuyGoods checkout. Keep a morning blood pressure log, and if the numbers do not move, email support before day 60: opened and empty bottles both qualify.