Guide
Probiotics explained: genus, species, strain and CFU
NIH defines probiotics as live microorganisms that provide health benefits when they are taken in sufficient amounts. Research is done on a named strain at a measured number of colony-forming units, and NCCIH says effects do not carry across from one organism to another. This page covers the four levels of identity, why a CFU count declines, what prebiotics and synbiotics are, and who should be careful.
By the Sodatide Editorial Desk · Medically reviewed by Dr. Meetal Mehta, Physician · Revised
- What a probiotic is
- The four levels
- Counts, and why they fall
- Prebiotics and synbiotics
- Safety and caution
- Reading a label
- Where this bottle lands
Definitions
A probiotic is an organism, and an amount of it
Two sources, read on September 30, 2026, and quoted rather than summarised.
NIH defines the word in one sentence: “Probiotics are live microorganisms (such as bacteria and yeasts) that provide health benefits when they are taken in sufficient amounts.” Almost everything difficult about this category is contained in the last five words of it.
A vitamin is a molecule, the same molecule in every bottle that contains it. A probiotic is not like that. It is a population of living things, which means it has an identity, a quantity and a shelf life, and all three have to be printed before a reader can do anything with the word.
NCCIH adds the regulatory frame: “Many probiotics are sold as dietary supplements, which don't require FDA approval before they are marketed.” That is not an accusation about any product. It describes the shelf, and it is why the rest of this page is about what a label has to earn rather than what an agency has checked.
Identity
Four levels, and a finding attaches to the last two
Genus, species, strain and amount. Choose a level to see what it is and what it is not.
Level one: the genus
The first word of the name, and the broadest. Lactobacillus, Bifidobacterium and Saccharomyces are genera: large families of organisms that share a general shape and not much else. A genus is closer to a surname than to a description of a person.
A label printing only a genus has told you the family and nothing about the member.
Level two: the species
The second word, set beside the first: L. rhamnosus, B. longum. This narrows the family to one kind of organism, and it is where most conversation about probiotics happens.
It is still not where research is done. Two organisms of the same species can behave differently enough that a finding about one is not a finding about the other.
Level three: the strain
The identifier after the species, often a short code of letters and digits. It is what a trial tests, because it is where an organism becomes a specific thing.
NCCIH is explicit about why that matters: “Different types of probiotics may have different effects,” in NCCIH’s words. “For example, if a specific kind of Lactobacillus helps prevent an illness, that doesn't necessarily mean that another kind of Lactobacillus or any of the Bifidobacterium probiotics would do the same thing.”
Level four: the amount
Colony-forming units per serving: how many live organisms are in the thing you swallow. NIH describes what a label of this kind usually carries: “The Supplement Facts label on a dietary supplement that contains probiotics lists the total weight of the microorganisms in the product. Many product labels also list the number of colony-forming units (CFUs) in a serving.”
The amount is not a detail alongside the identity, it is part of the definition. A probiotic with no published amount is a claim without a subject.
The levels are cumulative. A strain code is useless without the species above it, and a count is useless without something to count. A label reaching all four has given you enough to go and read the research yourself.
The count
What a CFU number is, and why the date attached to it matters
Colony-forming units measure how many organisms in a sample are alive enough to reproduce. It is a count of viable cells rather than a weight, which is why a probiotic label carries a different kind of number. NIH describes both: “The Supplement Facts label on a dietary supplement that contains probiotics lists the total weight of the microorganisms in the product. Many product labels also list the number of colony-forming units (CFUs) in a serving.”
The second thing NIH publishes about that number is the part most labels leave out: “The number of CFUs in a probiotic can decline over time. Therefore, the number of CFUs that a product contained when it was manufactured does not necessarily reflect the number of CFUs that the product contains when it is purchased or used.”
So a CFU figure is a measurement with a date on it, printed or not. A buyer holding a bottle is always further along that curve than the factory was, which is why storage instructions on a probiotic are part of the dose rather than housekeeping.
Prebiotics and synbiotics
Two more words from the same two sources
A prebiotic is food
NCCIH describes prebiotics as nondigestible food components that selectively stimulate the growth or activity of desirable microorganisms. No organism is being added; something is being fed.
A synbiotic is both together
NCCIH again: synbiotics are products that combine probiotics and prebiotics. A description of a design, not a claim about a result.
Why the distinction is practical
A prebiotic can be weighed. A probiotic has to be counted and kept alive, so a product combining them needs two different kinds of figure on its label.
What neither word settles
Whether any of it does anything for you. A shape is not evidence.
Safety
What the two sources say about risk, in their own words
Neither page is alarming and neither is blanket reassurance. Which sentence applies depends on who is reading.
What NIH says about healthy people
In healthy people, probiotics may cause gas, but they rarely cause infections or other health problems. A reassuring sentence, bounded by its first three words.
Who the same page flags
NIH adds that probiotics might also cause problems such as bacterial infections in people who are already seriously ill or who have weak immune systems.
What the category is not
NCCIH notes that many probiotics are sold as dietary supplements, which do not require FDA approval before they are marketed.
Where a decision belongs
With a clinician who knows your history, not with a checkout, and more so where a product does not say which strains are in it.
If any of this describes you, ask before you buy
NIH's caution is about people who are already seriously ill or who have weak immune systems. Anyone in hospital care or on immune-suppressing treatment is reading a different sentence from a healthy adult. Take the bottle to the appointment rather than the web page.
Reading a label
Five things to look for, in the order they are worth looking for
This works on any probiotic on any shelf, and is deliberately not about one product.
Find the organism names, and count the words
Three pieces should be there: genus, species and strain. Two of the three is common, and none at all means there is nothing to look up.
Find the number beside them
A CFU figure, per serving rather than per gram. NIH notes that a Supplement Facts label for a product containing probiotics lists the total weight of the microorganisms, and that many also give the colony-forming units in a serving.
Ask which date the number belongs to
A count at manufacture and a count at the end of shelf life are different numbers, and NIH says the first does not necessarily reflect what is in the bottle when it is bought.
Read the storage line as part of the dose
Live organisms are perishable in a way a vitamin is not. A label asking for refrigeration is telling you the count is sensitive to how the product is kept.
Read the cautions before the claims
NIH says probiotics rarely cause problems in healthy people, and separately that they might cause bacterial infections in people already seriously ill or with weak immune systems.
Where this bottle lands
The only section of this page that is about Sodatide
Run the five steps above against the label this site publishes and the first one ends it. The bottle prints Probiotic Blend and three species: no strain code and no CFU count, though the panel gives every amount. The label page sets it out line by line.
The consequence is narrow and worth stating precisely. It does not mean the organisms are absent, ineffective or unsafe. It means nothing published about probiotics can be attached to them in either direction. The one line conceding that an amount matters is the brand’s storage advice: refrigerate after opening to preserve the potency of the probiotics.
If a strain list and a CFU count are ever published, this page keeps its shape and the label page is rewritten around them. Documents to the website desk (address in the footer).
Read the label before the price
If you have read this page and still want to try it, three bottles is $69 each with 60 days to change your mind.
See the packs, from $49 a bottle
Order desk: listed in the footer · opening hours not published
Questions
Probiotics explained: common questions
What is a probiotic, exactly?
NIH defines probiotics as live microorganisms, such as bacteria and yeasts, that provide health benefits when they are taken in sufficient amounts. The amount sits inside the definition rather than beside it.
Why is the strain more important than the genus?
Because effects do not transfer. NCCIH says that if a specific kind of Lactobacillus helps prevent an illness, that does not necessarily mean that another kind of Lactobacillus or any of the Bifidobacterium probiotics would do the same thing.
What does CFU mean, and why do the numbers fall?
Colony-forming units: a count of how many live organisms a serving holds. NIH notes that the number of CFUs in a probiotic can decline over time, so the number at manufacture does not necessarily reflect the number at purchase or use.
What is the difference between a prebiotic and a probiotic?
A prebiotic is food, not an organism. NCCIH describes prebiotics as nondigestible food components that selectively stimulate the growth or activity of desirable microorganisms. Synbiotics combine the two.
Are probiotics safe to take?
NIH says that in healthy people, probiotics may cause gas, but they rarely cause infections or other health problems. It also says they might cause problems such as bacterial infections in people who are already seriously ill or who have weak immune systems.
Does the FDA approve probiotic supplements?
NCCIH puts it plainly: many probiotics are sold as dietary supplements, which do not require FDA approval before they are marketed.
How does this apply to Sodatide?
It applies by not applying. The label fills in the first two levels above, genus and species, and leaves the strain and the count blank, so published findings can be matched to the capsule only at species level.
References
- National Institutes of Health, Office of Dietary Supplements. Probiotics: Fact Sheet for Consumers. https://ods.od.nih.gov/factsheets/Probiotics-Consumer/
- National Center for Complementary and Integrative Health. Probiotics: What You Need To Know. https://www.nccih.nih.gov/health/probiotics-what-you-need-to-know
Every source above was opened and read on September 30, 2026. None of them tested Sodatide itself. They describe the named ingredients and the product category, which is a different thing from testing this finished formula.
Keep reading
Next on this site
Reading a gut supplement label
The checklist that follows from this page, with this product scored against it.
What the label prints
The full Supplement Facts panel, typed out, and the two things it leaves out.
Cautions and who should ask first
The NIH risk sentence in full, and the groups the label itself rules out.