As of 2001, probiotics have been defined by the World Health Organization’s (WHO) as “live micro-organisms which, when administered in adequate amounts, confer a health beneﬁt on the host.”
The health benefit of probiotics has seen its reach extend beyond the gut and across organs and metabolic systems. Still, little is known about what is actually an “adequate amount.”
Fortunately, Dr. Arthur Ouwehand, R&D Group manager at Danisco in Finland (and also an International Probiotics Association board member) has compiled a methodical review of studies investigating the dose-response relation of probiotics in human interventions. Ouwehand divided the studies as follows: meta-analyses, meta-analyses on specific probiotic strains, and tests with two or more doses of a probiotic in the same study.
Some of the probiotic effect using meta-analyses:
- In antibiotic associated diarrhea (AAD), a dose-response effect was suggested.
- In Clostridium difficile-associated diarrhea, no dose-response effect was seen.
- In necrotising enterocolitis, prevention of atopic dermatitis and slow intestinal transit, no dose-response relation was identified.
- In colorectal cancer and relief of irritable bowel syndrome, no dose-response relation was seen.
- In blood pressure modulation, higher doses of probiotics were more effective than lower doses.
Meta-analyses of specific strains
- a break-point for effectiveness of Lactobacillus rhamnosus GG in the treatment of acute gastroenteritis in children
- no dose-response was observed for two other probiotics assessed.
Tests with two or more doses
- fecal recovery and risk reduction of AAD
Ouwehand determined that probiotic dosing effectiveness in immune markers, general health, and bowel function did not show clear dose-response relations.
Nevertheless, he established that the clearest case for dose-response was with AAD where a higher dose of probiotics resulted in less AAD.
Ouwehand concluded that “…the absence of evidence for a dose-effect does not imply evidence of absence of a dose-effect. More and better quality studies will help in answering this question.”
He added that he would like to see studies with doses outside the commonly studied. Read this comprehensive review.