How to read a probiotic Supplement Facts panel: CFU, strains, and what a blend hides
A probiotic label has more ways to be technically accurate and practically unhelpful than almost any other kind of supplement. I reviewed dozens of them. This is the checklist I used, applied to the oral probiotic category, with ProDentim's publicly listed formulation as the running example because it is the one readers ask about.
CFU: what the number is and is not
CFU stands for colony-forming units. It is a count of viable bacteria, meaning bacteria capable of growing into a colony on a lab plate. It is the probiotic equivalent of a dose, and it is the first number to find.
Two things about it that labels rarely make clear.
First, the count is per serving, not per bottle. One tablet, one serving, 3.5 billion CFU in the ProDentim case. That is in the normal range for an oral product. Gut probiotics often carry 10 to 50 billion because they have to survive stomach acid; something you chew and let dissolve in your mouth does not, and the numbers in the oral trials I have seen are mostly in the 1 to 10 billion range.
Second, and this is the one that matters: the count is only meaningful if you know when it was measured. Live bacteria die in the bottle. A product can leave the factory at 5 billion and be at 2 billion by the best-by date. The FDA permits companies to list CFU and does not force them to say whether the number is at manufacture or guaranteed through expiration. The good labels say "guaranteed through expiration" or "at time of expiration." The ordinary labels say nothing, and the convention in the industry is that an unqualified number means "at time of manufacture," which is the most flattering way to count.
| What the label says | What it promises | What to assume |
|---|---|---|
| 3.5 billion CFU, no qualifier | The count when the batch was made | Less by the time you open it |
| 3.5 billion CFU at time of manufacture | Same, stated honestly | Same |
| 3.5 billion CFU through expiration | At least that count until the best-by date | The company overfilled to cover die-off |
The official product page for ProDentim gives the number without a qualifier. That is typical, not a red flag, but it is a question I would email the company.
Strain designations: genus, species, and the code after
A probiotic ingredient has three parts to its name, and the third is the one that matters most.
Lactobacillus is the genus. Paracasei is the species. Both are broad. There are thousands of distinct strains of L. paracasei in the world, some with trial data, most without. The strain is the specific culture, identified by a code: a number, a letter string, or a trademark. Bifidobacterium lactis BL-04 is a strain. "Bifidobacterium lactis" on its own is a species, and a label that stops at the species is telling you less than it seems to.
Why this matters: the clinical trials are done on strains, not species. Scan the abstracts in a PubMed search on L. reuteri and gingivitis and you will see each one names its strain. A study showing that L. reuteri strain X reduced gum bleeding says nothing about L. reuteri strain Y. When a sales page says "clinically proven," the question is whether the trial used the exact strain in the bottle. Often the answer is that the trial used a related strain from the same species and the page is rounding up.
On the ProDentim page, one of the three strains carries a code (BL-04, which is a trademarked strain from one of the large culture suppliers, with published safety and immune data). The other two, L. paracasei and L. reuteri, are listed at the species level on the sales page. I would want to see the strain codes on the bottle panel before I could say which trials apply. That is the single most useful question to put to any probiotic company: which strain, by code?
The proprietary blend
A proprietary blend is a group of ingredients listed together under one total weight. The rules, which you can read in the FDA's labeling guide, require the blend's total weight and the ingredients in descending order of weight. They do not require the amount of each ingredient. That is the point of the format, from the manufacturer's side: it protects the formula from being copied. From the reader's side, it means you know that ingredient A outweighs ingredient B, and nothing else.
For a probiotic this has a specific consequence. If three strains are listed under one CFU total, you do not know how that total is split. It could be a third each. It could be 90 percent of the cheapest strain and a sprinkle of the one with the trials. Both are legal. Both read the same on the label.
I am not accusing anyone of anything. I am telling you what the format conceals, because I used to sit on the other side of it. When a brand sent us a blend formula, the per-strain split was in the batch record, and it was never on the label, and it was often not what a consumer would have guessed.
"Other ingredients" and what they tell you
Below the panel is a list that begins "Other ingredients." This is everything in the product that is not an active, in descending order by weight. For a chewable tablet it usually includes a sweetener or sugar alcohol, a flavor, a flow agent so the powder runs through the press, a binder, and sometimes a coating.
Read this list for two things. The first is sugar, which in an oral product aimed at teeth would be absurd, and which I have seen anyway. The second is the length. A short list, four or five items, suggests a simple tablet. A long list suggests a lot of engineering to make something taste or hold together, and that is worth a thought.
The ProDentim page lists its non-strain ingredients, inulin, malic acid, tricalcium phosphate and peppermint, as part of the formula rather than as "other ingredients," which is a presentational choice. I cover each of those in the third article, including which ones are doing a job for you and which are doing a job for the tablet press.
The disclaimer and what it means
Every supplement that makes a structure-function claim ("supports healthy gums") must carry the sentence: "This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease." It is required by law. It is not a confession. It means the company is making the kind of claim that the rules allow without pre-approval, and that no agency has reviewed the evidence. The NCCIH probiotics page explains the regulatory status of probiotics specifically.
If a product makes a disease claim, "treats gingivitis," "cures bad breath," it has stepped into drug territory and is not allowed to. Watch for it. The honest products stay on the support side of the line, even when the website gets excited.
The checklist, condensed
- Find the CFU per serving. Ask whether it is at manufacture or through expiration.
- Find the strain codes, not just the species. Ask for them if they are missing.
- If there is a blend, understand that you do not know the split.
- Read the other ingredients for sugar and for length.
- Confirm the disclaimer is present and that the claims are support claims, not disease claims.
- Check the best-by date on the actual bottle, and buy the freshest.
Applied to the product in question: the ProDentim product page gives you the CFU total, the three strain names with one code, the four supporting ingredients, and the required disclaimer. What it does not give you, and what I would ask for before buying any probiotic, is the per-strain codes, the per-strain split, and the end-of-life CFU guarantee. Those three answers tell you more than any testimonial.