Through expiry vs at manufacture: what a probiotic CFU claim means

Picture two probiotic bottles side by side, both promising 25 billion CFU. One adds three small words: "through expiration date." The other doesn't. Those words can be the difference between what was in the bottle the day it was made and what's in the capsule the day you swallow it.

Here's how the two claims compare, why the difference exists, and what independent testing of probiotic products has found.

Why the count can change after a probiotic is made

Probiotics are living microbes, and in a dried supplement they're in a kind of suspended state. Keeping them alive on a shelf is a real manufacturing challenge. Dietary supplements and other dry products are expected to stay stable for up to 24 months at room temperature and humidity, and that depends on careful choices in how strains are grown, dried and formulated (Fenster et al., 2019).

The goal, as that review describes it, is a product that still delivers the required dose at the end of its shelf life (Fenster et al., 2019). Whether a label is written with that end point in mind is exactly what "through expiry" versus "at manufacture" tells you.

The two claims, side by side

"At time of manufacture"

• Tells you how many live microbes were in the product on the day it was made.
• Doesn't tell you how many remain after shipping, warehouse storage and weeks in your kitchen.
• Can make a product look stronger on paper than it is on the day you take it.

"Through expiration" or "guaranteed through expiry"

• Tells you the minimum count the maker commits to until the expiration date, as long as the product is stored as directed.
• Means the manufacturer has to plan for losses over the product's whole shelf life, not just the first day.
• Matches what pediatric gastroenterology experts in Europe have called for: probiotic content that meets the label "throughout the shelf life of the product" (Kolaček et al., 2017).

If a label shows a CFU number with no time point at all, it's safest to read it like the "at manufacture" version until the company tells you otherwise.

Do products actually match their labels?

Not always, which is why the wording matters:

• In a check of 13 probiotic products sold in the US in 2009, only 4 (31%) matched their label claims for the amount of live bacteria, the species present and the absence of contamination with other species (Drago et al., 2010).
• In a study of 26 supplements containing live bacteria sold in Slovenian pharmacies, 3 (12%) contained too few viable bacteria (Mohar Lorbeg et al., 2021).
• A European expert working group that summarized quality studies from around the world found deviations from labels were "surprisingly common." Problems included misidentified strains, bacteria that weren't viable, counts that couldn't be verified and occasional contamination (Kolaček et al., 2017).

These studies don't mean every product falls short. They mean a number printed on a bottle is only as good as the testing, formulation and storage behind it.

What "through expiry" can't promise

• It depends on storage. The guarantee is tied to the storage conditions on the label. A bottle kept in a steamy bathroom isn't covered by the same promise.
• It isn't a benefit claim. A guaranteed count tells you the microbes should be there. It doesn't tell you those strains were studied for your symptom.
• It's still the company's own promise. Independent testing adds another layer. Experts in probiotic quality have recommended third-party evaluation to certify quality and label accuracy, supported by standards from established organizations such as the United States Pharmacopeia (Jackson et al., 2019).

How to check a label in 30 seconds

1. Find the CFU number and look right next to it for "at time of manufacture" or "through expiration."
2. Check the expiration date, and plan to finish the bottle before it.
3. Read the storage instructions and make sure you can realistically follow them.
4. Look for full strain codes, so you can compare the dose with the studies on those strains.
5. If nothing is stated, ask the company how it tests its counts. A good one can answer.

The bottom line

"At manufacture" describes a starting point. "Through expiry" describes what you should still be getting at the end. Neither tells you whether a probiotic will help, but only one tells you what's likely to be in the capsule you actually take. For reference, Daily Biotic lists 25 billion CFU guaranteed through expiry across three named strains.

If you're taking a probiotic for ongoing symptoms and nothing is improving, or you notice red flags like blood in your stool or unexplained weight loss, check in with your doctor rather than switching products again.

Sources

1. Fenster K, Freeburg B, Hollard C, Wong C, Rønhave Laursen R, Ouwehand AC. The production and delivery of probiotics: a review of a practical approach. Microorganisms. 2019;7(3):83. PMID 30884906
2. Kolaček S, Hojsak I, Berni Canani R, et al. Commercial probiotic products: a call for improved quality control. A position paper by the ESPGHAN Working Group for Probiotics and Prebiotics. J Pediatr Gastroenterol Nutr. 2017;65(1):117-124. PMID 28644359
3. Drago L, Rodighiero V, Celeste T, Rovetto L, De Vecchi E. Microbiological evaluation of commercial probiotic products available in the USA in 2009. J Chemother. 2010;22(6):373-7. PMID 21303743
4. Mohar Lorbeg P, Golob M, Kramer M, Treven P, Bogovič Matijašić B. Evaluation of dietary supplements containing viable bacteria by cultivation/MALDI-TOF mass spectrometry and PCR identification. Front Microbiol. 2021;12:700138. PMID 34349743
5. Jackson SA, Schoeni JL, Vegge C, et al. Improving end-user trust in the quality of commercial probiotic products. Front Microbiol. 2019;10:739. PMID 31105649

This article is for general information and isn't medical advice. Talk to your healthcare provider before starting a supplement, especially if you have a medical condition or take prescription medication.