Probiotics, Prebiotics and Digestive Enzymes: Reading CFU and Strain Labels

By the nutrima editorial team · Last reviewed October 2026 · How we research and write

Short answer: Probiotics are live microorganisms, prebiotics are nondigestible food components (often fibers such as inulin) that feed microorganisms, and digestive enzymes are proteins that break food down into smaller parts. On a probiotic label, look for the full strain name (genus, species and strain code), the CFU count, and whether that count is stated "at time of manufacture" or "through expiration". NCCIH advises people with serious health problems, a weakened ability to fight infection, or a premature infant to talk with a healthcare provider before using probiotics.

In this guide:

Probiotics, prebiotics, synbiotics and enzymes

These four terms often appear on the same shelf, and sometimes in the same capsule, but they describe very different things.

Term What it is How it appears on a label
Probiotic Live microorganisms, usually bacteria and sometimes yeasts (NCCIH definition) Strain names and a CFU count
Prebiotic Nondigestible food components that selectively feed certain microorganisms (NCCIH definition) A fiber or carbohydrate by name and weight, e.g. inulin 500 mg
Synbiotic A product that combines probiotics and prebiotics (NCCIH definition) Both a CFU count and a prebiotic ingredient
Digestive enzyme Proteins that break down carbohydrates, proteins or fats into smaller parts Enzyme names with activity units, e.g. protease, amylase, lipase

According to NCCIH, the most common probiotic microorganisms belong to the groups Lactobacillus and Bifidobacterium. Other bacteria, and yeasts such as Saccharomyces boulardii, are also used. Probiotics are also found in yogurt and other fermented foods.

NCCIH makes an important point about differences between types: findings about one kind of Lactobacillus do not necessarily apply to another kind of Lactobacillus, or to any Bifidobacterium. That is why the full name on the label matters.

Genus, species and strain: reading the name

The NIH Office of Dietary Supplements (ODS) explains that probiotics are identified by their specific strain, which includes the genus, the species, the subspecies where there is one, and an alphanumeric strain designation. Here is how a typical name breaks down:

Part Example What it tells you
Genus Bifidobacterium The broad group
Species longum The specific type within the group
Subspecies (if any) infantis A further subdivision of some species
Strain designation A code of letters and numbers The exact strain; this is how it is identified in research

Some things you may notice when reading names:

  • Abbreviations. After the first mention, the genus is often shortened to its initial, as in L. acidophilus or B. lactis.
  • Renamed genera. In 2020, scientists split the large Lactobacillus genus into many smaller genera. As a result, you may see Lactobacillus rhamnosus labeled as Lacticaseibacillus rhamnosus, or Lactobacillus plantarum as Lactiplantibacillus plantarum. Older and newer names may appear on different products for the same species.
  • No strain code. Many labels list only genus and species. That tells you the type of organism but not the exact strain.
  • Spore-forming bacteria. Bacillus coagulans and some other Bacillus species form spores, a dormant, protected form of the bacterium. This is one reason storage instructions differ between products.

CFU: what the number means

CFU stands for colony forming units. It is an estimate of how many microorganisms in a serving are alive and able to multiply, based on how many colonies grow when a sample is cultured in a lab. A label might say "20 billion CFU" or "2 x 1010 CFU", which mean the same thing.

ODS notes that many probiotic supplements contain 1 to 10 billion CFU per dose, that some contain 50 billion or more, and that a higher CFU count does not necessarily mean a product has greater health effects. In other words, the CFU number is a quantity, not a ranking.

How CFU relates to the rest of the label:

  • US supplement labels must give the amount of each dietary ingredient by weight, so you may see a probiotic blend listed in milligrams. Many labels also show CFU, which tells you more about the live count than the weight does.
  • In a multi-strain product, the CFU is often given as a single total for the whole blend. The label may not say how the total is divided between strains.
  • Probiotics do not have a % Daily Value, so the %DV column shows an asterisk with "Daily Value not established".

For a broader walkthrough of serving sizes, units and proprietary blends, see our guide to reading a Supplement Facts label.

"At time of manufacture" vs "through expiration"

Probiotics are live, and some of the microorganisms die during storage. That makes the timing of the CFU count important:

Label wording What it means
"At time of manufacture" The count when the product was made. The live count on the day you take it may be lower.
"Through expiration" / "at end of shelf life" The amount the maker states will still be present up to the expiration date, when stored as directed.
No timing stated The label does not say which. You can ask the seller.

ODS recommends looking for products labeled with the number of CFU at the end of the product's shelf life, rather than at the time of manufacture. Whichever wording a label uses, the count assumes you follow the storage directions on the pack.

Prebiotics and fiber types

MedlinePlus describes fiber as a substance in plants and a type of carbohydrate, and notes that food labels may list it as soluble fiber or insoluble fiber. Soluble fiber dissolves in water; insoluble fiber does not. Some fibers are also called prebiotics, because microorganisms in the gut can use them as food.

Ingredient What it is Where you see it
Inulin A soluble fiber (a fructan) found in chicory root, onions, garlic and other plants Synbiotic capsules, powders, gummies
FOS (fructooligosaccharides) Shorter chains of the same building blocks as inulin Probiotic blends, powders
GOS (galactooligosaccharides) Short chains of galactose, often made from lactose Powders, some infant formulas
Polydextrose A soluble fiber made from glucose Strips, gummies, fortified foods
Psyllium husk A soluble fiber from the seeds of Plantago ovata that forms a gel in water Powders, capsules

Practical label notes for fiber products:

  • Fiber is listed in grams. Dietary fiber does have a Daily Value, so you may see a %DV figure.
  • Psyllium products commonly carry instructions to take them with a full glass of water or other fluid. Follow the label's fluid directions closely.
  • MedlinePlus advises adding fiber to your diet slowly, because increasing it too quickly can lead to gas, bloating and cramps.
  • Fiber can affect how some medicines are absorbed. If you take medication, ask your pharmacist how far apart to space them.

Digestive enzymes and their units

Digestive enzymes in supplements come from plants (such as bromelain from pineapple and papain from papaya), from microbial fermentation (fungal enzymes are common in vegan formulas), or from animal sources (such as pancreatin). Each enzyme acts on a specific type of food molecule:

Enzyme Acts on Common label unit
Amylase Starches DU
Protease Proteins HUT
Lipase Fats FIP or FCC LU
Lactase Lactose (milk sugar) ALU or FCC LacU
Cellulase Cellulose (plant fiber) CU
Bromelain / papain Proteins GDU, PU or FCC PU

Why units matter: an enzyme's weight in milligrams does not tell you its activity. Two products with 100 mg of protease can differ in activity, so activity units are the more useful figure. Units are only comparable when they are the same unit type. Many labels list weight, activity units, or both.

Related ingredients you may see in the same aisle:

  • Ox bile: dried bile from cattle, sold in capsules. Bile is a fluid made by the liver.
  • L-glutamine: an amino acid, usually sold as a powder measured in grams.

A label checklist

  1. Serving size: one capsule, two capsules, one strip, one scoop?
  2. Strain names: genus, species and, ideally, a strain code for each organism.
  3. CFU per serving: the total, and per strain if given.
  4. Timing of the CFU count: at manufacture or through expiration.
  5. Prebiotic ingredients: named, with an amount in mg or g.
  6. Enzymes: named, with activity units.
  7. Proprietary blend: if present, you see the total weight but not each ingredient's share.
  8. Other ingredients and allergens: capsule material, fillers, sweeteners, and any dairy, soy or other allergen statements.
  9. Storage instructions and expiration date.

Storage and refrigeration

Storage instructions vary between probiotic products, depending on the strains, the format and the packaging. Some say "refrigerate", others say "store in a cool, dry place". Follow the instructions printed on the product you have.

  • Heat, moisture and air reduce the number of live microorganisms over time. Keep lids closed tightly, and leave any desiccant packet in the bottle.
  • Do not store probiotics in a hot car, near a stove or in a steamy bathroom.
  • Strips and sachets are usually sealed individually; open them only when you are about to use them.
  • Digestive enzymes and fiber powders should be kept dry. Fiber powders can clump if they absorb moisture.
  • Use the product before the expiration date and keep all supplements out of reach of children.

Who should talk to a doctor first

NCCIH notes that the risk of harmful effects is greater in people with severe illnesses or a weakened ability to fight infection, and that cases of severe or fatal infection have been reported in premature infants given probiotics. The FDA has warned healthcare providers about this risk.

Talk to a doctor before using probiotics, prebiotics or enzyme products if you:

  • Have a serious underlying health condition. NCCIH says anyone in this group should be monitored closely while taking probiotics.
  • Have a weakened ability to fight infection, for example because of a medical condition, chemotherapy or medicines taken after an organ transplant.
  • Are considering a probiotic for a premature infant or a seriously ill hospital patient.
  • Are pregnant, breastfeeding or under 18.
  • Take prescription medicines, including antibiotics.
  • Have a digestive symptom that is new, severe or ongoing. NCCIH advises not to use probiotics as a reason to postpone seeing your healthcare provider about any health problem.

NCCIH also reports that some probiotic products have been found to contain microorganisms other than those listed on the label.

Shop this category

Browse our probiotics, enzymes and fiber collection. A selection, described by what each contains and its format. Check the Supplement Facts on each product page for the full strain list, CFU timing and storage directions:

Related guides: Apple cider vinegar, berberine and green tea extract · Mushroom supplements and mushroom coffee · All nutrima guides

Frequently asked questions

Is a higher CFU count better?

Not necessarily. ODS notes that a higher CFU count does not necessarily mean greater health effects. CFU is a quantity of live microorganisms; the specific strains matter as much as the number.

What is the difference between a probiotic and a prebiotic?

A probiotic is a live microorganism. A prebiotic is a nondigestible food component, often a fiber such as inulin, that microorganisms can use as food. A product with both is called a synbiotic.

What does "CFU at time of manufacture" mean?

It is the live count when the product was made. Because some microorganisms die during storage, the count on the day you use it may be lower. A count stated "through expiration" is what the maker states will remain until the expiration date when stored as directed.

Do probiotics need to be refrigerated?

Some do and some do not. It depends on the strains and packaging. Follow the storage instructions on the product's label.

Why does the strain code matter?

Research is done on specific strains, and NCCIH notes that results for one type do not necessarily apply to another, even within the same genus. A strain code identifies exactly which organism is in the product.

Why did Lactobacillus names change?

In 2020, scientists reclassified the Lactobacillus genus into many smaller genera. For example, Lactobacillus rhamnosus is now Lacticaseibacillus rhamnosus. Labels may use either name.

Who should avoid probiotics without medical advice?

NCCIH highlights people with severe illnesses, people with a weakened ability to fight infection, and premature infants. Anyone with a serious health condition, and anyone pregnant, breastfeeding or under 18, should talk to a doctor first.

Sources

These statements have not been evaluated by the Food and Drug Administration. This product information is not intended to diagnose, treat, cure, or prevent any disease. Talk to your doctor before starting any supplement.