What a CFU count does and does not tell you

Exhibit 01

What a colony-forming unit actually is

The CFU figure is the only amount printed anywhere on this panel for a dietary ingredient, and it is in a unit most readers have never had defined for them.

NIH ODS gives the definition in one sentence: “The number of viable cells in a probiotic supplement is indicated by the number of colony-forming units (CFU) listed on the label.” ^{NIH ODS}

The number of viable cells in a probiotic supplement is indicated by the number of colony-forming units (CFU) listed on the label.

Three things follow, and all three matter later. A CFU is a count, not a mass: it answers how many, not how much. It counts viable cells, so it is a figure about living material and therefore about storage, age and handling as well as about what was put in. And it is per dose as declared, which here means per 1 gummy, because the serving is 1 Gummy and the bottle holds 30.

What a CFU is not is a dose in the sense a reader usually means. NIH ODS is direct about how hard a probiotic label is to read for that purpose: “it can be difficult to determine which products offer verifiable health benefits due to the wide variety of probiotic strains and doses found in probiotic products and inconsistent labeling practices” ^{NIH ODS} That is the state of the published evidence for the category, not a statement about this product.

Exhibit 02

What this panel prints, and what it does not

The line itself, with everything the panel does and does not attach to it.

Two things on that line are done correctly and this post says so first. The dagger is right: the footnote reads † Daily Value Not Established, no Daily Value exists for a probiotic species, so no percentage can be calculated and none is printed. And the organism is named to species rather than to genus.

What is not there is a weight. Not in milligrams, not in grams, not anywhere on the panel or in the Other Ingredients line. The weight of Bacillus coagulans is first on the list of things this label does not publish: The panel quantifies it in CFU and in nothing else. 21 CFR 101.36(b)(3)(ii)(A) requires other dietary ingredients to be expressed in metric measures.

Nor is there a strain. The panel names the species and stops, which is the reason the ODS sentence quoted above bites: a reader with a species name and a cell count is working a level above the one published probiotic research is usually reported at.

Exhibit 03

The band NIH ODS describes, and both halves of it

One federal sentence puts a number beside a CFU count, and it describes the marketplace rather than setting a threshold. It is quoted here with the sentence that follows it, because the two were published together and separating them changes what they say.

Many probiotic supplements contain 1 to 10 billion CFU per dose, but some products contain 50 billion CFU or more.

However, products with higher CFU counts are not necessarily more effective than products with a lower CFU count.

Set the printed figure against the first. 500 Million CFU is 500,000,000 colony-forming units, and the lower end of the band ODS describes is a billion, so this bottle sits below the band by a factor of about 2.

Now the second sentence, the one that stops the first from being a verdict: “However, products with higher CFU counts are not necessarily more effective than products with a lower CFU count.” ^{NIH ODS}

Both halves of that comparison travel together on this site, always, because either one on its own misleads. A band describing what products contain is not an effective dose and not a minimum. It tells a reader where this label sits among other labels, which is a fact about labels. ODS declines to turn it into a fact about effect, and so does this post.

Exhibit 04

A count where the regulation asks for a weight

The CFU figure is also in the wrong unit for the line it sits on, and that part is quoted regulation rather than interpretation.

21 CFR 101.36(b)(3)(ii)(A) governs the amounts of other dietary ingredients on a Supplement Facts panel: “These amounts shall be expressed using metric measures in appropriate units.” ^{21 CFR 101.36} A colony-forming unit is not a metric measure of quantity in that sense. It is a count.

Two things have to be said about that guidance and this post says both. It is draft and non-binding, so it is not a rule this panel has broken, and anyone presenting it as one is overstating it. And the underlying regulation it offers discretion against is binding, and asks for a metric weight this panel does not carry.

So the position is narrow. The weight of Bacillus coagulans in a Renew31 gummy is not published. The count is published, the unit the regulation names is not, and FDA considered and declined the request to make the count sufficient on its own.

Exhibit 05

And the fact that settles it: no federal dose for this species

Everything above compares a printed count against sentences about probiotics in general. This last step is what stops any of it becoming a verdict about this bottle.

So there is no figure to hold 500 Million CFU against for this organism, in either direction. It cannot be called low, because nothing published says what low would be for this species, and it cannot be called sufficient for the same reason. The comparison with the band ODS describes is a comparison with other products, not with a dose.

That is less satisfying than a verdict. It is also the only answer the sources support. No published trial on the finished Renew31 formula was supplied with this stock and none appears in any source this desk opened. Every reference on this site describes a single named ingredient, a category of products, or a labelling regulation.

The cautions page carries the rest of the published cautions, who it is for sets out who the material names, and the batch page weighs the lot code and the certificate reference against the documents nobody supplied.