Probiotics
Brief description
Probiotics are live bacteria or yeast (microbes) that may have positive effects on or inside your body. They add to the existing supply of friendly microbes and may help to control harmful types of bacteria.
Not all probiotics are the same, some types of bacteria may be more beneficial than others. Additionally, probiotics are not regulated by the FDA, so there is no burden of proof for its benefit from any manufacturer(1).
Probiotics can naturally be found in:
Yoghurt and/or Kefir
Cottage cheese
Miso
Kombucha
Sauerkraut or kimchi
Pickles.
Evidence base
Irritable bowel Syndrome (IBS): Supplementation of probiotics was able to improve symptoms of IBS(2-5), in particular, abdominal pain(2, 3, 5), straining(2) and bloating(3, 5).
They seem to have a greater short rather than long-term benefit on IBS-symptoms(4), with B.Coagulans(2) and or Bacillus probiotics(4) demonstrating the most effective relief of IBS symptoms versus others.
Other studies however, reported weak evidence of probiotics on IBS symptoms(5, 6) and no significant improvement in quality of life(3, 5).
Conclusion – Possible short term improvement in symptoms may be experienced.
Prevention of Antibiotic Associated diarrhoea (AAD): A systematic review of 42 studies (n=11305 participants) found probiotics plus antibiotics reduced the risk of AAD by 37% (risk ratio (RR)=0.63 (95% CI 0.54 to 0.73), p<0.00001). Lactobacillus and bifidobacteria genera were found to be most effective(7).
Improved gut-barrier function: A systematic review of 26 randomised trials found probiotic supplementation improved intestinal barrier function, alleviates inflammation and microbial dysbiosis (imbalance of microbes in the gut)(8).
However, it is unclear clinically how this translates to improved health outcomes.
Recommended serving & duration.
No clear consensus on optimal dosage or duration. Lactobacillus and bifidobacterial seem to be most effective depending on outcome.
But lack of research to support “immune function”, and it is unclear how improvements in “gut barrier function” improve health clinically.
Safety & tolerability
Depending on source of probiotics, generally considered safe and well tolerated – especially if from whole foods rather than supplements.
References
Clinic C. Probiotics Cleveland Clinic2024 [Available from: https://my.clevelandclinic.org/health/treatments/14598-probiotics.
Zhang T, Zhang C, Zhang J, Sun F, Duan L. Efficacy of Probiotics for Irritable Bowel Syndrome: A Systematic Review and Network Meta-Analysis. Front Cell Infect Microbiol. 2022;12:859967.
Konstantis G, Efstathiou S, Pourzitaki C, Kitsikidou E, Germanidis G, Chourdakis M. Efficacy and safety of probiotics in the treatment of irritable bowel syndrome: A systematic review and meta-analysis of randomised clinical trials using ROME IV criteria. Clin Nutr. 2023;42(5):800-9.
Chen M, Yuan L, Xie CR, Wang XY, Feng SJ, Xiao XY, et al. Probiotics for the management of irritable bowel syndrome: a systematic review and three-level meta-analysis. Int J Surg. 2023;109(11):3631-47.
Wang Y, Chen N, Niu F, Li Y, Guo K, Shang X, et al. Probiotics therapy for adults with diarrhea-predominant irritable bowel syndrome: a systematic review and meta-analysis of 10 RCTs. Int J Colorectal Dis. 2022;37(11):2263-76.
Goodoory VC, Khasawneh M, Black CJ, Quigley EMM, Moayyedi P, Ford AC. Efficacy of Probiotics in Irritable Bowel Syndrome: Systematic Review and Meta-analysis. Gastroenterology. 2023;165(5):1206-18.
Goodman C, Keating G, Georgousopoulou E, Hespe C, Levett K. Probiotics for the prevention of antibiotic-associated diarrhoea: a systematic review and meta-analysis. BMJ Open. 2021;11(8):e043054.
Zheng Y, Zhang Z, Tang P, Wu Y, Zhang A, Li D, et al. Probiotics fortify intestinal barrier function: a systematic review and meta-analysis of randomized trials. Front Immunol. 2023;14:1143548.
