What is in a probiotic product
These products contain live microorganisms, mostly bacteria from the genera Lactobacillus and Bifidobacterium, sometimes with Streptococcus thermophilus, Lactococcus lactis or the yeast Saccharomyces boulardii. Many also contain FOS (fructooligosaccharides), a type of fibre, listed separately in milligrams. Some add other ingredients, such as cranberry fruit in the Swanson women's formula.
How to read CFU
CFU stands for colony-forming units. It is the count of live cells that the manufacturer states for the product. Check whether the number is given per capsule or per daily dose. NOW Foods Probiotic-10 states 25 billion CFU per capsule and 50 billion CFU in a daily dose of 2 capsules. Some labels give one total, and others list CFU for each strain, as Swanson Epic Pro does. A label may also give the weight of the bacterial blend in milligrams, such as 20 mg. That weight is not the CFU count.
How to read strain names
A full name has three parts: the genus, the species and the strain code. In Lactobacillus paracasei Lpc-37, Lactobacillus is the genus, paracasei is the species and Lpc-37 is the strain. Two products can contain the same species but different strains, and only the code lets you see whether two labels list the same culture. Some labels give the species only, without codes. Since 2020 many Lactobacillus species have new genus names, for example Lacticaseibacillus rhamnosus, so newer labels may use those names.
| Product | Strains | CFU per daily dose | Strain codes on label |
|---|---|---|---|
| NOW Foods Probiotic-10 | 10 | 50 billion (2 capsules) | no |
| Swanson Epic Pro 25 Strain | 25 | 30 billion (1 capsule) | for most strains |
| Swanson Women's Daily with cranberry | 15 | 35.1 billion (2 capsules) | yes |
| Swanson 16 Strain with FOS | 16 | listed per strain (1 capsule) | no |
| Swanson Probiotic-4 | 4 | 3 billion (1 capsule) | no |
| Swanson Oral Probiotic, BLIS K12 | 5 | 3 billion (1 lozenge) | BLIS K12 only |
| Swanson Probiotic for Kids | 4 | 3 billion (1 lozenge) | no |
How to take and store
Take the dose on the label. NOW Foods suggests taking the capsules between meals or on an empty stomach, while Swanson Probiotic-4 is taken in the evening with a meal. Lozenges are sucked, not swallowed. Storage matters with live cultures: Swanson Probiotic-4 should be kept at 17 to 22 °C, the BLIS K12 lozenges in the refrigerator after opening and the kids' lozenges chilled.
Who should ask a doctor
Most labels in this category say the products are not recommended during pregnancy or breastfeeding. NOW Foods and the Swanson women's formula ask you to consult a doctor if you take medicines or have a medical condition, and NOW Foods names specific medicines on its label.
Probiotic benefits: why we do not list them
Probiotics are among the most searched supplements, usually together with the word benefits. In the EU, a food supplement may carry only health claims that the European Commission has authorised and listed in the EU Register of nutrition and health claims. The European Food Safety Authority (EFSA) has assessed a large number of claims for bacterial cultures, and none has been authorised. In many of those opinions the cultures were not described precisely enough down to the strain, which is one more reason why strain codes on a label are worth checking. For a shop this means we may not say what a culture does in the body. We compare what is on the label: which strains, how many CFU per daily dose, how to store the product and the price per day. The NCCIH page under Sources summarises what research has looked at, in plain language.
Questions
Which probiotic is best?
No label lets you pick one best product, and we cannot rank them by effect. Compare what you can read: strains with codes or without, CFU per daily dose rather than per capsule, extra ingredients such as FOS or cranberry, storage needs and the price per day.
When should I take probiotics?
It depends on the product. NOW Foods suggests taking its capsules between meals or on an empty stomach, while Swanson Probiotic-4 is taken in the evening with a meal. Follow the label of the pack you have.
Are there probiotics for children?
Swanson Probiotic for Kids is a lozenge with 4 strains and 3 billion CFU in one lozenge. It should be kept chilled.
Is more CFU better?
CFU is a count, not a measure of effect. The EU has not authorised any health claim for bacterial cultures, so we compare products by count, strains and price per day.
Why does one product need refrigeration and another does not?
Manufacturers set storage conditions for their own cultures and packaging. Follow the instructions on the pack you buy.
Sources
- NCCIH: Probiotics, usefulness and safety
- ISAPP consensus statement on the scope and use of the term probiotic (PubMed)
- EUR-Lex: Regulation (EU) No 432/2012 (permitted health claims)
- EFSA: Health claims
Content reviewed by Inese Kalniņa, dietitian.
2026-09-02