Probiotics – do they benefit healthy people?
A systematic review has found that probiotics have little effect on the gut microbiota of healthy people.
The study was undertaken by researchers at the Novo Nordisk Foundation Center for Basic Metabolic Research at the University of Copenhagen and published in Genome Medicine.
It involved a review of seven randomised controlled trials to investigate the effect of probiotics on the faecal microbiota of healthy adults. The probiotics products administered were biscuits, milk-based drinks, sachets, or capsules for periods of 21 to 42 days.
The researchers looked at reported effects on the overall structure of faecal microbiota including the number of species present, the evenness and whether the healthy people taking probiotics had different changes of bacteria living in their guts compared to the placebo groups.
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The researchers investigated the trials for reported effects of probiotics on the overall structure of the fecal microbiota of healthy adults, including the number of species present, the evenness (distribution of species within the populations) and whether the probiotics groups of study participants as a result of the intervention had different changes in bacteria living in their gut than the placebo groups.
“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,” PhD student and junior author Nadja Buus Kristensen said.
Of the seven original trials, only one found observed changes in the bacterial composition of faecal microbiota.
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The authors note that various limitations include small sample size, use of different probiotic strains, variations of diet and variation in susceptibility of probiotics between individuals could mask the true impact of probiotic intake.
Oluf Pedersen, professor at the University of Copenhagen and senior author of the paper said: “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. 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.”