Can probiotics influence microbiota composition? A review of randomized controlled trials

[A.B.]

Alterations in fecal microbiota composition by probiotic supplementation in healthy adults: a systematic review of randomized controlled trials

Conclusions
This systematic review of the pertinent literature demonstrates a lack of evidence for an impact of probiotics on fecal microbiota composition in healthy adults.

http://genomemedicine.biomedcentral.com/articles/10.1186/s13073-016-0300-5

I do wonder if things might be different in sick adults. Still it doesn't look good.

 

[Skippa]

Any similar trials for prebiotics?

 

[alicec]

The results don't surprise me at all. Most of the commonly used probiotic species are not ones that colonise the gut, nor do they reflect the composition of the gut flora.

This doesn't mean that probiotics do nothing. They do exert effects on the immune system as they transit through the gut and probably play a role in crowding out other (undesirable) species.

There have been a number of studies showing that prebiotics do indeed influence the composition of the gut flora. I am not aware of a comprehensive review though I haven't particularly looked for one. Maybe someone else has come across one.