Probiotics (multi-strain)
Live bacteria that colonise the gut transiently. Most benefit comes from strain-specific use cases — generic 'probiotic' isn't a single intervention.
Strong for: antibiotic-associated diarrhea (any time you take antibiotics, take a probiotic 2 hours apart), C. difficile prevention (S. boulardii), IBS-D symptom relief, ulcerative colitis remission (VSL#3 / Visbiome), and traveller's diarrhea (L. rhamnosus GG). Weaker / mixed: general 'gut health,' immune support, mood. Effects: 2–4 weeks for symptom-targeted use.
Probiotics are live microorganisms — usually Lactobacillus and Bifidobacterium species, sometimes Saccharomyces yeasts — that, when consumed in adequate amounts, confer a health benefit. They mostly don't permanently colonise the gut; their effects come from transient activity (modulating local immunity, producing short-chain fatty acids, displacing pathogens, supporting the mucus layer). The key insight: effects are strain-specific, not species-specific or generic. A study showing Lactobacillus rhamnosus GG works for traveller's diarrhea says nothing about a random L. rhamnosus product. For most healthy people without GI issues, the marginal benefit is small. The big wins are during/after antibiotics, in IBS, and for specific conditions matched to specific strains.
- Form
- Refrigerated multi-strain blends with named strains and CFU counts at expiration (not at manufacture). Spore-based (Bacillus coagulans, B. subtilis) — heat-stable, no refrigeration. Branded condition-specific formulations: VSL#3 / Visbiome (IBS, UC), Seed DS-01 (general / travel), Florastor (S. boulardii — antibiotic diarrhea), Culturelle (L. rhamnosus GG).
- Dose
- 5–50 billion CFU/day from a labelled, multi-strain product. Higher doses (100–450 billion, VSL#3 territory) for IBS or UC. CFU number matters less than strain identity.
- Timing
- With food or shortly before — buffers stomach acid that would otherwise kill the bacteria. AM or PM.
- Schedule
- Daily during a course (typically 4–12 weeks). Long-term continuous use is fine but the marginal benefit drops once gut flora rebalances. Resume during/after antibiotics or travel.
- Side effects
- Initial bloating, gas, mild GI upset (first 1–2 weeks as flora rebalance). Rarely: histamine release (in mast-cell-sensitive individuals — some Lactobacillus strains produce histamine).
- Interactions
- Take 2 hours apart from oral antibiotics (the antibiotic kills the probiotic).
- Contraindications
- Severe immune compromise (organ transplant on immunosuppressants, neutropenia from chemotherapy, advanced HIV) — risk of probiotic-derived sepsis. Central venous catheter in place (rare risk of fungemia from S. boulardii). Critical illness in ICU (mixed evidence). Histamine intolerance (avoid histamine-producing strains).
- Lab markers
- Stool microbiome analysis (uBiome / Viome / Doctor's Data style) — interpretive utility debated. Symptom tracking is more practical for most.
- Food sources
- Fermented foods contain live cultures: yogurt, kefir, sauerkraut, kimchi, miso, tempeh, kombucha, traditional pickles (brine, not vinegar). Eating these regularly delivers a steady, varied supply of live bacteria — often more effective than capsules for general 'gut health.'
Pairs with
Prebiotics (inulin, GOS, PHGG — the fibres that feed gut bacteria). Fermented foods (yogurt, kefir, sauerkraut, kimchi — naturally probiotic). L-glutamine (gut lining support). Saccharomyces boulardii alongside antibiotics specifically.
within Probiotics & gut