What we liked
- Strain names, not blends, are the first thing to check
- A CFU guarantee to expiry is worth more than a bigger number at manufacture
- Cost per serving is the only price comparison that works across pack sizes
What we did not
- Most labels do not state the CFU guarantee clearly
- Proprietary blends hide the dose, which makes a product impossible to assess
Probiotic labelling is loosely regulated. A bottle can print “50 billion CFU” in enormous type and never tell you which strains are inside, how much of each, or whether any of it was still alive when the bottle reached your kitchen.
Five things on the label are worth your attention. Everything else is marketing.
1. Strain names, not blends
A label that says “Lactobacillus blend, 20 billion CFU” has told you the genus and nothing else. Lactobacillus is a genus containing hundreds of species, and the effects people attribute to probiotics are strain-specific.
What you want to see is the full name: genus, species, and a strain code — something like Lactobacillus rhamnosus GG, where “GG” identifies the specific strain. If a product lists quantities per strain, better still. If the quantities are hidden behind the word “blend”, you cannot assess the dose, so you cannot assess the product.
2. Guaranteed to expiry, not at manufacture
This is the single most useful sentence on a probiotic label, and most products bury it or omit it.
“50 billion CFU at time of manufacture” means the count when it left the factory. Live organisms die over time, faster in heat and humidity. By month eighteen, a meaningful fraction may be gone. “50 billion CFU through the printed expiry date” is a promise about what you actually get when you swallow it.
If the label does not say which one it is, assume the less useful one.
3. Storage
Follow the label, and be honest about your kitchen. A probiotic that says “refrigerate” and lives in a warm cupboard is degrading. Shelf-stable formulas are usually the better choice if you live somewhere humid or travel.
Once a bottle is open, moisture is the main threat. A standard screw-top with no desiccant lets humid air in every time you take a capsule. If the product matters to you, transfer it to an airtight jar.
4. Capsule type
A capsule that dissolves in the stomach releases its contents into acid. A delayed-release or enteric-coated capsule is designed to survive longer. This is worth checking, and it is one of the few claims you can verify cheaply at home: a capsule left in a mild acid solution for 45 minutes should still be intact.
5. Cost per serving
Divide the pack price by the number of servings — not the number of capsules, which is how brands make a 30-day supply look like a 60-day one. Two products sitting at the same shelf price can differ threefold in daily cost.
What to ignore
“Clinically studied” with no citation. It is marketing until there is a study name.
The CFU arms race. Higher counts are not automatically better. A well-documented 15 billion beats an anonymous 100 billion, and very high doses are more likely to cause the first-week bloating people complain about.
Proprietary blends. If the amounts are hidden, the product cannot be reviewed.
When not to take one at all
If you are immunocompromised, recovering from surgery, or being treated for a serious illness, talk to a clinician before adding any live-culture supplement. Live microorganisms are not risk-free for everyone, and this is not a category where a review site should be your only source.
Reference
| What CFU means | Colony-forming units — a count of viable organisms |
|---|---|
| Where the count should be guaranteed | To the printed expiry date, not to manufacture |
| Strain naming standard | Genus + species + strain code |
| Storage | Follow the label; shelf-stable is easier in humid climates |
| Typical general-use dose | Often in the tens of billions of CFU |