A CFU count tells you how many bacteria were in the capsule when it was made — not how many are alive when you swallow it, and not whether those particular bacteria have been studied for anything. The strain designation is the part of the label that carries information.
Probiotics are the one supplement category where the headline number has become almost purely competitive. Ten billion became twenty, then fifty, then a hundred, and none of that escalation reflected a finding that more is better. It reflected the fact that a bigger number is easier to print than an explanation.
Why 40 billion is not four times 10 billion
CFU stands for colony-forming units — a count of viable organisms. The problem is not that the number is fake. It is that a count without a strain attached is not a dose of anything.
Different strains have been studied at wildly different amounts, from around a billion to well over a hundred billion, depending on the organism and what the trial was measuring. So a 50 billion product containing organisms nobody has studied is not a stronger version of a 10 billion product built on a strain with trials behind it. They are not on the same scale, and there is no exchange rate between them.
Genus, species, strain — the last one is the whole thing
Take Lactobacillus rhamnosus GG. Lactobacillus is the genus, rhamnosus the species, and GG the strain — a specific, banked, traceable organism. Essentially all of the research attaches to that third part.
This matters more than it sounds. Two products can both say "Lactobacillus acidophilus" and contain organisms that behave differently, because species-level identity is a loose category. A label naming only genus and species has told you roughly what family the bacteria belong to and nothing about what they do. A label naming La-14, or Bl-04, or Lp-115 has told you exactly which organism is in the capsule, which means you can go and read about it.
What the label is and isn't telling you
| What it says | What that tells you | What it leaves out |
|---|---|---|
| "50 Billion CFU" | How many organisms were counted at some point | Which organisms, when they were counted, and how many survive to expiry |
| "15 strains" | Variety, presented as a virtue | Whether any of the fifteen is present at an amount anyone has studied |
| "L. acidophilus" | The species | The strain — so nothing you can look up |
| "L. acidophilus La-14" | The exact organism, traceable to published work | Nothing. This is what a useful probiotic label looks like |
| "Guaranteed through end of shelf life" | The count you are buying is the count you will get | Nothing — this is the guarantee you want |
| "Proprietary blend, 800mg" | The combined weight | How the CFU total is divided between the strains |
The second number: when the count was counted
Live cultures die over time, faster when warm. So the CFU figure on a bottle is only meaningful alongside the point at which it is guaranteed.
"At time of manufacture" means the count was taken in the factory, and whatever happened during shipping, warehousing and the months on your shelf comes out of it. "Guaranteed through end of shelf life" means the manufacturer is standing behind the number at the expiry date, which is the only version that describes what you will actually swallow. A product with a smaller number guaranteed to expiry can easily beat a bigger number guaranteed at manufacture.
Storage is the other half of it. Some formulations need refrigeration and some are built to be shelf-stable; neither is inherently better, but a refrigerated product left in a hot delivery van has lost something the label cannot tell you about.
Which should you actually buy?
- If you are choosing on the biggest CFU number — stop, and choose on the strain list instead. The CFU figure is the least informative number on the panel.
- If you want a strain the research used — find the designation, then buy a product that names it. Whose logo is on the bottle matters much less than whether the code is printed.
- If you just want something general and daily — a moderate count of named strains with an end-of-shelf-life guarantee is fine, and it does not need to be expensive. This is most people.
- If you are travelling or have just finished a course of antibiotics — Saccharomyces boulardii is a yeast rather than a bacterium, measured differently and worth researching specifically rather than assuming a bacterial product covers it.
- If you are immunocompromised, or have a central line — do not self-prescribe live cultures. This is a documented risk, not a precautionary disclaimer, and it is a conversation to have with a clinician.
Reading a probiotic label in ten seconds
- Look for strain codes. Letters and numbers after the species name. If they are absent, nothing else on the label can be checked.
- Find the guarantee point. "At manufacture" or "through end of shelf life". If it does not say, assume the former.
- See whether CFU is split by strain. A single total across ten strains hides how little of each is in there.
- Check the storage instruction. Then check whether the seller shipped it that way.
- Read the expiry date, not the manufacture date. On this one product category, that difference is the product.
What we do
Verelia Probiotic 40 Billion with Prebiotics contains four strains named at strain level — Lactobacillus acidophilus La-14, Bifidobacterium lactis Bl-04, Lactobacillus plantarum Lp-115 and Lactobacillus paracasei Lpc-37 — at 40 billion CFU total, in a shelf-stable capsule with a marine polysaccharide delivery system and 24mg of fructooligosaccharide. Two capsules daily, 60 capsules, 30-day supply.
Two things to be straight about. The bottle leads with the number this article has just told you not to shop on, and it does that because it is the number people search for — we would rather say so than pretend otherwise. And the four strains sit inside an 800mg proprietary blend, so the 40 billion is a combined figure and the split between the four is not disclosed. That is the same criticism we made of other people's labels three paragraphs ago, and it applies here.
What the label does do is name all four organisms precisely enough that you can go and read about each of them, which is the part we would defend.
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. Live cultures are not appropriate for everyone — speak to your healthcare provider before starting a probiotic, particularly if you are immunocompromised, seriously unwell, or have an indwelling catheter or central line.
Comments