Probiotics: what the label can and can't tell you

This article is general information, not medical advice. Talk to a doctor or pharmacist about your own situation, especially if you're pregnant, immunocompromised or giving anything to an infant.

"Probiotic" is a category, not a product#

Probiotics are live microorganisms. Studies look at specific strains for specific purposes, and results for one strain don't apply to others. A label that only says "Lactobacillus" tells you the genus. A useful label gives the genus, species and strain code, such as a letter-and-number combination after the species name.

Look for the strain#

If a company cites research, check that the research was done on the same strain at a similar dose. Some strains have studies behind them for particular uses. Many don't. A product made with a generic "blend" and no strain information is hard to assess.

Read the dose#

Doses are given in colony-forming units (CFU), often in billions. A higher number isn't automatically better. What matters is the dose used in studies of that strain. Check that the label states the amount at the end of shelf life, not just at manufacture, since live organisms decline.

Storage#

Some products need refrigeration. Others are formulated for room temperature. Follow the instructions, and check the date.

Format#

Capsules, drops, chewables and drinks all exist. Delivery can matter because organisms must survive stomach acid. Companies should say how they protect them.

Health claims#

Claims for supplements are regulated differently from medicines. In the EU and UK, only authorised health claims may be made, and few probiotics have approved ones. In the US, supplements can make structure and function claims but not claims to treat disease, and they carry a standard disclaimer. A product promising to cure something is a red flag.

Food versus supplements#

Fermented foods such as yoghurt with live cultures, kefir, sauerkraut and kimchi contain beneficial microbes, though they differ from the studied strains in supplements. A varied diet with plenty of fibre also supports gut bacteria.

What we'd do#

Check the strain, dose and storage, then see whether there is research that matches your reason for taking it. Ask a pharmacist if unsure. And check the price per daily dose, not per bottle.