Probiotic CFU and strains: how to read a probiotic label
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To read probiotic CFU and strains on a label, look for three things: the full name of each strain (genus, species and a strain code such as GG or LA85), the number of colony-forming units (CFU) per daily serving, and whether that number is guaranteed until the expiry date or only at manufacture. A bigger CFU number is not automatically better: research shows that results depend on the specific strain, not the headline count.
Probiotic CFU and strains: the essentials in 30 seconds
| On the label | What to look for | Red flag |
|---|---|---|
| Strain name | Genus + species + strain code (e.g. Lacticaseibacillus rhamnosus GG) | Only "Lactobacillus blend" or species without a code |
| CFU | A number per daily serving, e.g. 10 billion CFU per 2 capsules | A total per bottle, or only milligrams |
| Timing of the count | "At expiry" or "through end of shelf life" | "At time of manufacture" |
| Typical range | Many products: 1–10 billion CFU per dose (NIH) | Assuming 50 billion is five times better than 10 |
| Storage | Clear instructions (room temperature or refrigerate) | No storage guidance at all |
What CFU means on a probiotic label
CFU stands for colony-forming units: an estimate of how many live, viable microbes a serving contains. The NIH Office of Dietary Supplements notes that many probiotic supplements contain 1 to 10 billion CFU per dose, and some contain 50 billion or more.
The same NIH fact sheet adds a point that marketing tends to skip: products with higher CFU counts are not necessarily more effective than products with lower counts. The amount that matters is the one used in studies of that specific strain, which is why the strain name comes before the number.
Two practical checks: make sure the CFU figure refers to the daily serving (if the dose is 2 capsules, divide accordingly), and in the US remember that labeling rules only require the total weight of the microorganisms in milligrams. According to NIH, that weight has no relationship with the number of live microbes.
CFU at manufacture vs. at expiry
Probiotics are living organisms, and their numbers fall over time with heat, humidity and oxygen. A count stated "at time of manufacture" tells you what went into the capsule, not what is left when you take it months later.
NIH advises looking for products labeled with the number of CFU at the end of shelf life and avoiding those that only list CFU at manufacture. If the label doesn't say which, it's a fair question to ask the seller before buying.
Storage matters too: follow the label. Some strains need refrigeration; others are designed to stay stable at room temperature if kept cool and dry.
Probiotic strains: genus, species and strain code
A probiotic's full name has three parts. Take Lacticaseibacillus rhamnosus GG: Lacticaseibacillus is the genus, rhamnosus the species, and GG the strain designation. NIH uses this as its example of how probiotics are identified.
The strain code is not a detail. A 2018 systematic review by McFarland and colleagues analyzed 228 randomized trials and found strong evidence that probiotic results are both strain-specific and specific to the condition studied: some strains showed an effect while other strains of the same species did not. That's why a study on one strain can't be borrowed to describe another.
What this means when you compare products
- A label that lists only species (for example "L. acidophilus") is not wrong, but it makes it impossible to match the product to published research.
- More strains is not automatically better. Look for strains with their own studies, not long lists.
- If a product mentions research, check that it was done on the same strain code.
Why probiotic names changed in 2020
If you see unfamiliar names, it's not a typo. In April 2020, a taxonomic revision published in the International Journal of Systematic and Evolutionary Microbiology split the old genus Lactobacillus and described 23 new genera. Many labels still use the older names.
| Older name | Current name |
|---|---|
| Lactobacillus rhamnosus | Lacticaseibacillus rhamnosus |
| Lactobacillus paracasei | Lacticaseibacillus paracasei |
| Lactobacillus plantarum | Lactiplantibacillus plantarum |
| Lactobacillus acidophilus | Lactobacillus acidophilus (unchanged) |
The organism is the same; only the label name changes. Bifidobacteria were not affected.
What EU rules allow us to say about probiotics
The word has a scientific definition: the 2014 ISAPP expert consensus describes probiotics as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. That is exactly why European regulators read the word as a claim.
We're a European company, and in the EU a food or supplement can only be linked to health effects the European Commission has authorized. For probiotic supplements, there is no authorized health claim. Several EU authorities have treated the word "probiotic" itself as an implied health claim, while others, such as Spain since October 2020 and Italy, accept the term on labels as long as no unauthorized claim goes with it.
The only authorized claim for live bacteria in Regulation 432/2012 applies to yogurt, not supplements:
"Live cultures in yoghurt or fermented milk improve lactose digestion of the product in individuals who have difficulty digesting lactose." The yoghurt or fermented milk must contain at least 108 CFU of live starter microorganisms (Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus) per gram.
Regulation (EU) 432/2012
Probiotics are not nutrients, so neither EFSA nor NIH sets a tolerable upper intake level for them. That's why the right dose is the one on the label, based on the strain.
How to read a probiotic label in 6 steps
- Find the serving: "per capsule" or "per 2 capsules". Every number refers to it.
- Read each strain's full name: genus, species and code. Note which ones have no code.
- Check the CFU per serving, not per bottle, and whether it's in CFU or only in mg.
- Look for "at expiry": a count guaranteed through shelf life beats one at manufacture.
- Check the storage instructions and the best-before date.
- Work out the cost per day: price divided by real servings, not by capsules.
Check first: NIH notes that probiotics are unlikely to cause harm in healthy people and side effects are usually minor, but serious infections have been reported in people who were severely ill or immunocompromised, and in preterm infants. If you're pregnant, breastfeeding, taking medication, have a weakened immune system or a medical condition, or want to give probiotics to a child, talk to a healthcare professional first.
FAQ: probiotic CFU and strains
How many CFU should a probiotic have?
There's no single right number. Many supplements contain 1 to 10 billion CFU per dose, and NIH notes that higher counts aren't necessarily more effective. The useful amount is the one studied for that specific strain.
Is a 50 billion CFU probiotic better than a 10 billion one?
Not automatically. Results depend on the strain and what it was studied for, so a well-identified strain at a studied dose tells you more than a bigger headline number.
What does the strain code on a probiotic label mean?
It's the letters or numbers after the species, such as GG or LA85. It identifies one specific strain, and research on probiotics is strain-specific.
Does "CFU at time of manufacture" matter?
Yes. Live microbes decline over time, so a count at manufacture can be higher than what's left at expiry. Prefer labels that guarantee CFU through the end of shelf life.
Why does my probiotic say Lactiplantibacillus instead of Lactobacillus?
In 2020 the genus Lactobacillus was split into 25 genera, adding 23 new ones. Lactiplantibacillus plantarum is the same organism once called Lactobacillus plantarum.
Can I take probiotics while pregnant or on medication?
Check with a healthcare professional first. The same applies if you have a weakened immune system or a medical condition, or before giving probiotics to children.
Ivalro probiotics
Ivalro ships to the US and the EU; our probiotic costs €23.90 for 60 capsules, 30 days at 2 capsules a day (about €0.80 per day), and its page lists the four species and the total CFU.
Probiotic 40 Billion CFUFour species plus FOS fiber, 60 capsules.View product →
Digestive BlendL. acidophilus LA85 with inulin and enzymes.View product →
The same logic applies to any supplement: read how to read a supplement label, or browse digestion and microbiome.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Dietary supplement. Not intended to replace a varied and balanced diet or a healthy lifestyle. Do not exceed the recommended daily dose.
Ivalro editorial team. Written from EU regulations and published scientific reviews, linked below. Last reviewed: October 2026. For information only: not a substitute for advice from a healthcare professional.
Sources
- EU Regulation 432/2012 — authorized health claims (including live yoghurt cultures)
- NIH Office of Dietary Supplements — Probiotics: Fact Sheet for Health Professionals
- McFarland et al. Strain-specificity and disease-specificity of probiotic efficacy: a systematic review and meta-analysis (Front Med, 2018)
- Zheng et al. A taxonomic note on the genus Lactobacillus: description of 23 novel genera (IJSEM, 2020)
- Hill et al. ISAPP consensus statement on the scope and appropriate use of the term probiotic (Nat Rev Gastroenterol Hepatol, 2014)
- ISAPP — "Probiotic" on food labels in Europe: Spain adopts a pioneering initiative (2020)
