Probiotic CFUs: What “At Manufacture” and “Through Expiration” Mean on a Label

A probiotic count “at time of manufacture” tells you how many live organisms the maker counted when the product was made. A count “through expiration” (also worded “at end of shelf life”) tells you how many the maker says will still be there on the printed date, if you store the product as directed. Only the second one speaks to the bottle you are holding. If a label gives only the first, or prints a number with no timing words at all, read it as a starting figure, not a promise about what you will get later.

This guide explains what each phrase means, what the numbers can and cannot tell you, and gives you a label annotation card you can fill in for any probiotic, whether it is a capsule, gummy, powder or drink mix. It is a general label-literacy guide. For a look at how one product's label measures up, see our PrimeBiome review, which notes that the product's label shows no live-organism count and no named strain.

What the two phrases mean

CFU stands for colony-forming units. The International Probiotics Association (IPA), an industry association, describes CFU as the accepted unit for labeling how many live probiotics a product contains (IPA, 5 Essentials for Quality Probiotic Label). The number alone does not tell you when it was counted. These are the three patterns you will see:

“10 billion CFU at time of manufacture.” (Example wording, not a real product.) This is the count when the product was made. It does not say what is left by the time you open it.
“10 billion CFU through expiration date,” or “at end of shelf life.” The maker is claiming that amount will remain until the printed date under the stated storage conditions. The IPA says an expiration date should show how long the product holds its claimed count when stored as directed, and that products should contain the declared amount at the end of shelf life, not just at manufacture. Best-practices guidelines from the IPA and the Council for Responsible Nutrition (CRN) make the same labeling recommendation, and trade press describes those guidelines as voluntary (Food Business News). They are not an FDA rule.
“10 billion CFU” with no timing words. The label does not say when the count applies. You cannot tell which of the two situations you are in.

Why a manufacturing count cannot guarantee the end-of-shelf-life count

Probiotics are living organisms, and their numbers change. The International Scientific Association for Probiotics and Prebiotics (ISAPP) explains that most probiotic strains lose cells over the course of shelf life, and some strains lose them faster than others (ISAPP, Decoding a Probiotic Product Label). The IPA adds that probiotics are generally sensitive to temperature and humidity, and that the effect depends on the strain, the formulation, the dosage form and the packaging. So two products that start at the same number can end up at different numbers on their expiration dates.

Makers can plan for this. A CRN white paper, quoted on an IPA page about storage, says probiotics are often manufactured with extra organisms so the claimed amount is present at the end of shelf life when stored as directed. That is why the timing words matter. From the package you cannot tell how much extra, if any, a maker added. You can only tell whether the maker is willing to state the count through the date.

Many labels leave this out. ISAPP reports on two surveys of products sold in the Washington, DC area. In the supplement survey, 45% of products did not give a measure of potency through the end of shelf life. That is one region's survey, not a national figure, but it shows that a missing timing statement is common.

What U.S. labeling guidance does and does not say

FDA's Dietary Supplement Labeling Guide, still posted by FDA and dated April 2005, says expiration dating is not required on dietary supplements. A firm may include a date if valid data show it is not false or misleading (FDA Guide, Chapter I). The guide also says its contents are nonbinding recommendations. Its general-labeling and nutrition-labeling chapters do not address how live-organism counts should be stated.

In plain terms, a missing date or a missing timing phrase is a gap in the information you are given. The guide does not treat dating as mandatory, so checking falls to you.

The label annotation card

Use this card once per product. Copy the exact wording from the package, not from the seller's web page, because the package is what you will be holding.

1. Strain name

Write down: the genus, species and strain code for every organism, exactly as printed.
Gap if: the label lists only a genus or a group name. ISAPP notes labels sometimes list only “bifidobacteria” or “lactobacilli.”
For how strain codes work and why they matter, see our guide to the strain identifier on a probiotic label. This article stays on counts and dates.

2. Amount

Write down: the number, the unit (CFU), and the serving it applies to. FDA's guide defines one serving as the maximum amount the label recommends per eating occasion. If the directions say 1 to 3 capsules, the serving is 3.
Look for timing words next to the number: “at time of manufacture,” “through expiration” or “at end of shelf life,” or nothing.
Multi-strain products: a single total does not show how much of each strain is in the product, according to ISAPP.
Milligrams or blend weights: a weight is not a live-organism count. The IPA says milligrams do not correspond to the activity of the formula, and FDA's guide says a proprietary blend lists a combined weight for the blend.

3. Date

Write down: the exact words and which date it is: expiration, “best by,” or a manufacture or lot date.
The IPA separates an expiration date, which should show how long the claimed count lasts when stored as directed, from a manufacture date, which only records when the product was made.
Gap if: there is no date, or only a lot code. Other date wordings, such as “best by,” may not carry the same promise, so ask the maker what its date covers.

4. Storage language

Write down: the storage directions word for word. Examples of wording you may see include “store in a cool, dry place” or “refrigerate after opening.”
Why it belongs on the card: a count claim goes with the storage conditions named alongside it. The IPA says correct storage helps keep the organisms viable until the expiration date.
Gap if: there are no directions, or they are vague about temperature, humidity or opened packages.

5. What the package does not state

Tick off what is missing: timing words with the count, any date, strain names, storage directions, and a contact for the maker. (A 2002 FAO/WHO working-group list, reported by ISAPP, includes corporate contact details among the items a probiotic label should carry.)
Watch for a count that appears on a web page or ad but not on the package.
A gap is not a verdict on safety or quality. It means the claim cannot be checked from the package.
If there are gaps, ask the maker: Is the count stated through the expiration date? What date is printed on this lot, and what does it cover? What storage conditions does the count assume?

Fill-in version

Product and package size: ______
Strain names (genus, species, strain code): ______
Amount and serving: ______ CFU per ______
Timing words next to the amount: manufacture / expiration / none
Date printed and what it is: ______
Storage directions: ______
Not stated on the package: ______
Questions for the maker: ______

Two invented example labels

These are made-up labels to show how the card works. They are not real products and no testing is implied.

Label A: “20 billion CFU at time of manufacture. Best by 06/2028. Store in a cool, dry place.” The card shows a manufacturing count only, so the amount in the last months before the date is not stated. “Best by” is also not clearly an expiration date. This label leaves two questions for the maker.
Label B: “10 billion CFU per capsule through expiration date when stored as directed. Exp. 06/2028. Refrigerate after opening.” The count, date and storage line fit together, so each field has an answer. That is a clearer statement than Label A's, though you still cannot confirm it by reading.

Label A's bigger number cannot be compared with Label B's smaller one. They were counted at different times.

What a count through expiration still does not tell you

It is the maker's statement. Reading a label cannot verify it.
It is not evidence of benefit. The National Center for Complementary and Integrative Health (NCCIH) says that in most cases researchers still do not know which probiotics help, how much people would need, or who is most likely to benefit (NCCIH, Probiotics: Usefulness and Safety, last updated August 2019).
It does not confirm what is in the product. NCCIH notes that some probiotic products have been reported to contain microorganisms other than those listed on the label.
It is not an approval. NCCIH explains that many probiotics are sold as dietary supplements, which do not need FDA approval before they are marketed.

Who should check with a clinician first

Probiotics contain live organisms. NCCIH says the risk of harmful effects is greater in people with severe illnesses or weakened immune systems, and that the FDA warned health care providers in 2023 about severe, potentially fatal infections in premature infants given probiotics. NCCIH advises talking with a health care provider before using a probiotic supplement, especially if you have health problems. If that may apply to you or someone you care for, see our review of probiotic safety in immunocompromised patients, and bring your completed card to your pharmacist or clinician. This article is general information, not medical advice. See our medical disclaimer.

Your next step

Pick one probiotic you already own or are considering and fill in the card from the package. If the amount has no timing words and the date is missing, you have learned what the package does not tell you, and you know what to ask the maker. If the amount, date and storage directions all line up, you have a clearer claim to evaluate, not proof that the product works for you.

By DrBayer.com Editorial Team