Probiotics
Probiotics are live microorganisms that, when taken in adequate amounts, fall under the widely used international definition of the term. The word does not name a single substance: it covers a large number of microorganisms that differ from one another at strain level. Most products on the market use bacteria of the genera Lactobacillus and Bifidobacterium, along with some yeasts.
Probiotics are classified by genus, species and strain rather than by chemical structure, which sets them apart from every other ingredient on these pages. The naming system has three parts — for example Lacticaseibacillus rhamnosus GG, where the first term is the genus, the second the species and the last an alphanumeric strain code. The literature is consistent that probiotic properties are strain-specific, so data from one strain cannot stand in for another even within the same species. Probiotics are also quantified in colony-forming units, or CFU, which counts live organisms rather than a weight in milligrams. This page describes the ingredient itself and is not a statement about any particular product. Dietary supplements are not intended to prevent, treat or cure any disease.
About this ingredient
Probiotics are not nutrients; they are organisms. Only a few genera account for most of what is used in supplements and functional foods: Lactobacillus and the genera split out from it, Bifidobacterium, Streptococcus, Bacillus, and the yeast genus Saccharomyces. What complicates the picture is that taxonomy changes. In 2020 the former genus Lactobacillus was divided into several new genera on genomic evidence, among them Lacticaseibacillus and Limosilactobacillus, so an older and a newer name on two labels may refer to the same organism.
Dietary sources
Probiotics are not an essential nutrient, so there is no Thai RDI and no EU nutrient reference value. In an ordinary diet these organisms occur in fermented foods that have not been heated after fermentation: yoghurt declaring live cultures, cultured milk drinks, kimchi, pickled vegetables, miso and tempeh. In Thai cooking they occur in naturally fermented pickled vegetables and pla som. Two things are worth noting. Fermented foods that are heated afterwards, such as bread and canned products, contain no live organisms. And most fermented foods do not state which strains they contain or in what numbers, so they cannot be compared directly with a supplement that declares a strain and a CFU count. Commercial raw material is produced by culturing selected strains and then freeze-drying them, which leaves the organisms dormant until they meet moisture again.
Forms & absorption
Probiotic raw materials differ in three respects: the strain, the CFU count, and how viability is preserved. Most clinical trials use doses in the range of about 1 × 10⁸ to 1 × 10¹⁰ CFU a day, with many settling around 1 × 10⁹. The main obstacles are stomach acid and bile, so strains are typically selected for acid and bile tolerance. Spore-forming strains such as Bacillus coagulans are inherently more heat- and acid-resistant and are therefore shelf-stable at room temperature. Products come as capsules, sachets and drinks; some require refrigeration and some do not, depending on the strain and the drying technology. Advice on whether to take them with food varies by product, so the label is the guide.
Research status
Human research on probiotics is extensive and growing quickly, but it has a feature that makes it harder to summarise than research on ordinary nutrients: effects are specific to a strain and to an indication, so a result from one strain does not extend to another, even within the same species or genus. Reviews and practice guidance therefore stress that a recommendation must rest on evidence for the specific strain named, not for the genus or species. The practical consequence is that a product declaring only a species name, with no strain code, cannot be tied to any particular study. No claim has been approved by the Thai FDA for the products on this site. This page therefore presents probiotics here as an ingredient, not as a benefit.
Safety & considerations
Probiotics are the exception among the ingredients on these pages: they do not appear in the annex to the Thai FDA guidance on the use of key ingredients in dietary supplements dated 8 July 2024, because probiotic microorganisms are governed by a separate notification that lists the strains permitted in food. This page therefore states no maximum daily figure for probiotics, and readers should follow the amount printed on the label of the product in front of them. On safety, the literature agrees that probiotics have a good record of use in healthy adults, but that safety assessment has to be done strain by strain, because bacteraemia and sepsis from lactobacilli have been documented in immunocompromised or critically ill hospitalised patients. If you are immunocompromised, have a central venous catheter, are caring for an infant, are pregnant or breastfeeding, or take prescription medicines, speak to a doctor or pharmacist before starting. Dietary supplements are not intended to prevent, treat or cure any disease.
Quality markers
Five things are worth checking on a probiotic label. First and most important: whether all three parts are declared — genus, species and strain code. A product naming only a species cannot be tied to any published study. Second, the CFU count and the point at which it is counted; some labels state the number at manufacture and others at end of shelf life, and those are different numbers. Third, for multi-strain products, whether CFU is given per strain or only as a total. Fourth, the storage condition, which should say whether refrigeration is needed, since these are living organisms and their numbers fall with time and temperature. Fifth, the expiry date, which carries more meaning here than on an ordinary product. Every dietary supplement sold in Thailand also carries an FDA (อย.) registration number on the label.
- NIH Office of Dietary Supplements – Probiotics Fact Sheet for Health Professionals ↗
- Zheng et al. (IJSEM 2020) – Genomic reclassification of the genus Lactobacillus ↗
This page is general educational information about a nutrient — it describes the nutrient itself and is not a statement about any particular product. Dietary supplements are food, not medicine, and have no effect in preventing or treating disease. The references listed above are public-institution sources, not product claims.
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