Probiotics
Live micro-organisms (mainly Lactobacillus and Bifidobacterium bacteria) which, taken in sufficient quantity, bring a benefit to gut and immune health.
Probiotics are defined by the WHO as « live micro-organisms which, when administered in adequate amounts, confer a health benefit on the host ». The most studied strains include Lactobacillus rhamnosus GG, Saccharomyces boulardii, Bifidobacterium longum and Lactobacillus plantarum.
Documented effectiveness:
- After antibiotics, L. rhamnosus GG or Saccharomyces boulardii reduce the risk of diarrhoea by 40-60% (Cochrane 2024)
- 80-95% effectiveness against recurrent Clostridium difficile infections (faecal transplant)
- Improvement in symptoms of anxiety or depression in some people (early studies, needing confirmation)
A fresh angle: for probiotics to work, you need:
- At least 10⁹ CFU (colony-forming units) per dose
- Identified strains (not a vague « flora » mix)
- At least 8-12 weeks of use (colonisation takes time)
- A favourable environment: food rich in prebiotics, no chronic stress, no concurrent antibiotics (which would kill them)
The great myth: probiotics do not replace a healthy lifestyle. A personalised 2022 study shows that probiotics colonise in some people, while in others they simply pass through and disappear, so the individual’s genotype matters a lot.
Selection rule: do not choose by « feeling ». Identify the problem (after antibiotics? IBS dysbiosis? anxiety?) and choose a strain validated for that problem.