Guide
How to choose a good probiotic
A good probiotic names its strains, dates its CFU count and matches a tested dose. Our label lists species only and counts CFU at the time of manufacture, and we show where that falls short.
A good probiotic names its strains (genus, species and a strain code), states how many live cells each carries and when they were counted, and matches a dose that a trial of that strain used. Most labels fall short of one of these, including ours: species only, 20 billion CFU at the time of manufacture.
1. Look for strain codes, not just species
A probiotic's name has three parts: genus, species and strain, such as Bifidobacterium animalis subsp. lactis BB-12 or Lacticaseibacillus rhamnosus GG. The code at the end is what identifies the organism a trial tested. A review of 249 trials covering 22 types of probiotic found that efficacy was strain-specific and purpose-specific, and that many products lack confirmatory trials. A label that says only "L. acidophilus" gives you no way to connect it to any trial.
Names change too. The Lactobacillus genus was reclassified in 2020, so the same organism can appear as L. rhamnosus on one label and Lacticaseibacillus rhamnosus on another. Match the species and the code, not the spelling of the genus.
2. Check how many live cells, and when they were counted
CFU counts live microbes. The count can fall in storage, so the useful number is the count through the end of shelf life; a label that says "at the time of manufacture" is giving the count when the capsule was made. In a laboratory survey of probiotics sold in one market, almost none met their label claim, 11% had no viable cells and 27% varied significantly between batches. It is one market, not ours, but it is why a dated count and a certificate of analysis matter.
3. Compare the dose with a trial of that strain
A trial of one named strain in 64 healthy young adults used 10 billion CFU a day for 4 weeks. The point is the comparison: your product's strain, at your product's per-strain count, against a trial's. A dose-response review found that whether more does more depends on the outcome, so a bigger CFU number is not evidence of a better product. See how much probiotics per day.
4. Match the strain to your purpose
If you are buying for a reason, look for the strain's trial on that reason. If a page cites studies of "probiotics" without naming a strain, they are not evidence for the product. If the reason is a medical condition, ask a clinician. We review what trials found, with their limits, in probiotics benefits: what the research does and doesn't show.
5. Read storage, format and other ingredients
Some products are shelf-stable and some need refrigeration; follow the storage line for the one you buy, because live organisms can lose potency if stored wrongly. We found no head-to-head study of shelf-stable against refrigerated products to cite. Read the other ingredients as well: check for gelatin in the capsule, any added fiber or prebiotic you want to avoid, and allergens. If you need a dairy-free product, a label with no dairy ingredient does not tell you what the cultures were grown on, so ask the maker.
6. Price per serving, and testing
Divide the price by servings, and compare at the same count and strain. Ask whether a certificate of analysis exists for viable count and strain identity, and whether it covers the lot you are buying.
How our label measures up
Electric Tiger Probiotic 20 Billion CFU lists 20 billion CFU at the time of manufacture per capsule, from 13 listed organisms (L. acidophilus, L. salivarius, L. plantarum, L. rhamnosus, B. lactis, B. bifidum, L. fermentum, L. reuteri, B. longum, L. gasseri, B. animalis, L. paracasei and B. breve), as one 317 mg row. Against the checklist:
| Check | Electric Tiger Probiotic 20 Billion CFU |
|---|---|
| Strain codes | None printed. Species only, so no strain-specific research is attached to it. |
| Count per organism | None printed. One total for the whole row. |
| Count timing | 20 billion CFU at the time of manufacture; the count at purchase or expiry is not stated. |
| Dose vs a trial | No trial can be matched, because no strain is named. |
| Other ingredients | Cellulose (vegetable capsule) and brown rice flour; no added fiber or prebiotic. |
| Storage | Store cool and dry. |
| Price per serving | As low as $14.39 a bottle on subscription, 30 capsules, about $0.48 a serving. |
| Testing | We hold no certificate of analysis for viable count, so we do not claim third-party testing. |
Where it falls short is the first four rows. If a strain-level label matters to you, choose a product that prints strain codes and per-strain counts.
Questions people ask
Which probiotics are best, or best to take?
There is no best product in general. The right one for you is a named strain with a trial for your purpose, at a tested dose, from a maker who dates the count.
Which probiotics work best, or are best for gut health?
Probiotic effects are strain-specific, and 7 placebo-controlled trials in healthy adults showed no change in stool bacteria diversity. We have no basis to rank products.
Are there best probiotics for women or for men?
Marketing by audience does not change the checklist. The same checks apply.
Where can I buy probiotics, and where can I get them from food?
Pharmacies, health stores and online sellers all carry them; use the checklist wherever you buy. Fermented foods such as yogurt and kimchi are a different category from probiotics, according to ISAPP's definition of fermented foods, and are not labelled with strain codes in the same way.
Should I read reviews of a particular brand?
Reviews rarely report strain codes or dated counts. Read the label first.
Is there a probiotic for travel, or one that is dairy-free?
For travel purposes, we have no verified evidence to cite and ask you to check with a clinician. For dairy-free, see point 5.
Is a coupon or a lower price a sign of quality?
No. Compare price per serving at the same strain and count.
Related reading: what are probiotics and how to choose a good acidophilus.
Sources
- Choosing an appropriate probiotic product for your patient: An evidence-based practical guide A review of 249 trials found probiotic effects depend on the exact strain and the purpose, and many products have no trial of their own.
- Compositional Quality and Possible Gastrointestinal Performance of Marketed Probiotic Supplements A lab survey of probiotics sold in one market found almost none met their label claim and 11% had no viable cells.
- The effect of Lactobacillus paracasei subsp. paracasei L. casei W8® on blood levels of triacylglycerol is independent of colonisation In 64 healthy young adults, 10 billion CFU a day of one named strain for 4 weeks raised that strain's group in stool but did not change overall gut composition.
- A review of dose-responses of probiotics in human studies A review found that whether a higher probiotic dose does more depends on the outcome, and for most outcomes studied there was no clear relationship.
- Alterations in fecal microbiota composition by probiotic supplementation in healthy adults: a systematic review of randomized controlled trials A review of 7 placebo-controlled trials in healthy adults found probiotics did not change the diversity of stool bacteria.
- The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on fermented foods Experts define fermented foods by how they are made, and say they are not the same thing as probiotics.
*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.
