Your bowl of laban is alive, in a sense. Traditional fermented foods have always carried bacteria, and the idea that some microbes can be good for us is much older than the supplement industry. The word probiotic, however, has a specific meaning. An expert panel of the International Scientific Association for Probiotics and Prebiotics, writing in Nature Reviews Gastroenterology and Hepatology in 2014, reaffirmed the definition first set out by the FAO and the WHO: live microorganisms that, when given in adequate amounts, provide a health benefit to the person taking them.
Why strains matter
Bacteria have a three-part name. Take Lactobacillus rhamnosus GG as an example: Lactobacillus is the genus, rhamnosus is the species and GG is the strain. The classification of some of these bacteria has been updated, so you may see new genus names on labels.
The strain matters because, as the US National Center for Complementary and Integrative Health puts it, effects vary by strain, so a benefit from one strain does not mean another will help. NCCIH adds that in most cases it is still unknown which strains work, what dose is needed and who is most likely to benefit. A label that lists only species names tells you less than one that gives full strain designations.
What CFU means
CFU stands for colony forming units, an estimate of how many live microbes are capable of multiplying. When reading CFU on a pack, keep these points in mind:
- A higher number is not automatically more useful
- The effective amount depends on the strain and the purpose
- Look for a CFU count guaranteed through the expiry date, since counts can fall over time
- Heat can harm live bacteria, so follow the storage directions closely in summer
What the research says
Research on probiotics is large but uneven. The clearest example is diarrhoea during antibiotic treatment in children. A Cochrane review published in 2019 pooled 33 trials with 6,352 children taking antibiotics and found that those also given probiotics were less likely to develop diarrhoea, with the rate falling from 19 percent to 8 percent, a result the reviewers rated as moderate-certainty evidence. Higher daily doses appeared to work better than lower ones, and none of the trials that tracked side effects attributed serious harm to probiotics. NCCIH summarises other areas as mixed or insufficient, with no clear benefit shown for general wellness in healthy people. Results differ from person to person, partly because everyone's gut bacteria are different. Some people notice nothing at all. Others have temporary gas or bloating when starting.
Probiotics are not a replacement for fibre, varied food or medical care.
Fermented foods at home
Yoghurt, laban and kefir can be enjoyable parts of your diet, particularly if the product contains live cultures. Heating them, as in many cooked yoghurt dishes such as mansaf sauce, kills most of the bacteria, though the food remains nourishing. Pickles vary: those made with vinegar generally do not contain live cultures.
When to be cautious
NCCIH warns that the risk of harm from probiotics is greater in people with severe illness or weakened immune systems, and that premature infants given probiotics have developed severe infections. Talk to a doctor before using them if you have a weakened immune system, a serious illness, a central line or recent major surgery, and ask a paediatrician before giving them to infants. If you are pregnant or breastfeeding, check first. Do not self-manage these symptoms; see a doctor if you have:
- Blood in your stool or black stools
- Unexplained weight loss
- Persistent diarrhoea or abdominal pain
- Fever along with digestive symptoms
Sources
- The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic · Nature Reviews Gastroenterology & Hepatology
- Probiotics: Usefulness and Safety · National Center for Complementary and Integrative Health (NCCIH), NIH
- Probiotics for the prevention of pediatric antibiotic-associated diarrhea · Cochrane Database of Systematic Reviews
This article is general health information for educational purposes and is not medical advice. It does not promote any product. Talk to your doctor or pharmacist before starting a supplement, especially if you are pregnant, breastfeeding, have a health condition or take medication.