May 10, 2016
2 min read

Data lacking on effect of probiotics on gut microbiome of healthy adults

You've successfully added to your alerts. You will receive an email when new content is published.

Click Here to Manage Email Alerts

We were unable to process your request. Please try again later. If you continue to have this issue please contact

Available randomized controlled trial data do not support any effect of probiotic supplementation on the gut microbiota of healthy adults, according to research published in Genome Medicine.

“According to our systematic review, no convincing evidence exists for consistent effects of examined probiotics on fecal microbiota composition in healthy adults, despite probiotic products being consumed to a large extent by the general population,” Nadja Buus Kristensen, a PhD student at The Novo Nordisk Foundation Center for Basic Metabolic Research at University of Copenhagen, said in a press release.

Kristensen and colleagues performed a literature search in August 2015 and included seven randomized controlled trials in their final analysis, which were published between February 2013 and October 2015 and evaluated the effects of probiotic supplementation vs. placebo on fecal microbiota in healthy adults using shotgun metagenomics sequencing, 16S rRNA sequencing or phylogenetic microarray methods.

Study cohorts ranged from 21 to 81 individuals. Five of the studies evaluated probiotics belonging to the genus Lactobacillus, one evaluated Bifidobacterium and Lactobacillus combined, and one evaluated Bacillus, which were administered in biscuits, milk-based drinks, sachets or capsules at doses ranging from about 109 to 1011 colony-forming units for 21 to 42 days.

“The quality of the included studies is high in regard to risk of bias and the methods of assessing fecal microbiota configuration,” the researchers wrote. “However, blinding of health care providers, data collectors, and outcome assessors were either not performed or unclearly reported in three of the seven included studies, which may have caused performance and detection bias. Two studies only investigated the effect of the probiotic treatment on a subgroup of participants, which is also a potential source of bias.”

The primary measures of treatment effects included microbial richness, abundance, evenness, alpha- and compositional dissimilarity (or beta-diversity). A meta-analysis was not performed due to heterogeneity of study designs and methods.

No effects on fecal microbiota composition were observed in any of the studies compared with placebo with the exception of one study that found probiotic treatment significantly modified beta-diversity.

“While there is some evidence from previous reviews that probiotic interventions may benefit those with disease-associated imbalances of the gut microbiota, there is little evidence of an effect in healthy individuals,” Oluf Pedersen, MD, professor at the University of Copenhagen said in the press release. “To explore the potential of probiotics to contribute to disease prevention in healthy people there is a major need for much larger, carefully designed and carefully conducted clinical trials. These should include ideal composition and dosage of known and newly developed probiotics combined with specified dietary advice, optimal trial duration and relevant monitoring of host health status.” – by Adam Leitenberger

Disclosure s : The researchers report no relevant financial disclosures.