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Probiotics

Live beneficial bacteria that restore gut microbiome balance

Evidence Grade: B — Good clinical evidence Gut Health

What is Probiotics?

B
Evidence Grade B: Good clinical evidence Our evidence grades reflect the quality, volume, and consistency of human clinical trials for the primary uses of this ingredient.

Probiotics are live microorganisms that confer health benefits when consumed in adequate amounts. They primarily work by colonising the gut temporarily, competing with pathogenic bacteria, producing short-chain fatty acids (SCFAs) and bacteriocins, modulating immune responses via gut-associated lymphoid tissue (GALT), and strengthening the intestinal epithelial barrier. The gut microbiome contains 100 trillion bacteria from ~1,000 species — imbalances (dysbiosis) are linked to IBS, IBD, obesity, mental health disorders, and immune dysfunction.

Evidence-Based Benefits of Probiotics

IBS symptom relief

Multiple RCTs and meta-analyses show specific probiotic strains (Lactobacillus acidophilus NCFM, Bifidobacterium infantis 35624) reduce IBS pain, bloating, and bowel irregularity. AGA clinical guidelines recommend probiotics for specific IBS subtypes.

Antibiotic-associated diarrhoea prevention

Cochrane review of 23 RCTs found probiotics reduce antibiotic-associated diarrhoea risk by 61%. Lactobacillus rhamnosus GG and Saccharomyces boulardii are the most studied strains.

Immune modulation

70% of the immune system is located in the gut. Probiotic supplementation reduces upper respiratory infection frequency and duration, particularly in children and the elderly.

Mental health (gut-brain axis)

Emerging 'psychobiotics' research shows specific strains reduce anxiety and depression scores. L. rhamnosus and B. longum strains show consistent effects in animal and early human trials.

Vaginal health

Lactobacillus crispatus and L. rhamnosus GR-1 + RC-14 maintain vaginal pH and reduce recurrence of bacterial vaginosis and urinary tract infections.

Cholesterol reduction

Lactobacillus reuteri NCIMB 30242 reduces LDL cholesterol by up to 11.6% and total cholesterol by 9% versus placebo in RCTs.

Best Forms of Probiotics to Buy

Not all forms of probiotics are created equal. Bioavailability — how much the body actually absorbs and uses — varies significantly between forms. Ranked from most to least recommended:

★★★★☆
Multi-strain formulas (10+ strains)
Broader coverage; important to match strains to condition
★★★★★
Single-strain targeted (e.g., L. rhamnosus GG)
Most evidence-based for specific conditions
★★★★☆
Spore-forming (Bacillus coagulans)
Heat-stable; survives stomach acid; no refrigeration needed
★★★★★
Saccharomyces boulardii (yeast)
Non-antibiotic-susceptible; gold standard for antibiotic protection
★★★★☆
Fermented foods (kefir, kimchi, sauerkraut)
Real food matrix; lower CFU count but diverse strains

Dosage Guide

Standard5–50 billion CFU/day depending on condition
Upper LimitNo established UL; generally safe up to 100 billion CFU/day
TimingWith or 30 minutes before a meal (buffered by food reduces stomach acid kill-off). Take 2+ hours apart from antibiotics.
NotesCFU count matters less than strain specificity. Check that your product specifies the exact strain (e.g., Lactobacillus rhamnosus GG, not just 'Lactobacillus rhamnosus'). Third-party tested products should show live CFU count at expiry, not just at manufacture.

Drug & Supplement Interactions

Always inform your doctor or pharmacist if you are taking probiotics alongside prescription medications. Key interactions to be aware of:

Medium
Antibiotics
Antibiotics kill probiotic bacteria. Take probiotics 2+ hours after antibiotics and continue for 2 weeks post-antibiotic course.
High
Immunosuppressants
Severely immunocompromised individuals (organ transplant, chemotherapy) should avoid probiotics — risk of bacterial translocation.

Signs of Probiotics Deficiency

N/A — probiotics are not an essential nutrient, but dysbiosis signs include: bloating, irregular bowel habits, frequent infections, skin issues

Top Food Sources of Probiotics

Kefir (up to 12 strains, 25–30 billion CFU/cup)
Sauerkraut (unpasteurised)
Kimchi
Miso
Tempeh
Kombucha (variable, often lower CFU than claimed)

Safety & Side Effects

⚠ Safety Information

Safe for healthy adults. Rare risk of sepsis in severely immunocompromised patients — avoid in this population. Transient bloating and gas common in first 1–2 weeks as microbiome adjusts. Yeast-based probiotics (S. boulardii) are safe with antibiotics.

This information is for educational purposes only. Always consult a qualified healthcare professional before starting any supplement, especially if you have a medical condition or take medications.

References & Clinical Citations