One downside w/ probiotics. “Bacteroides fragilis metabolises exopolysaccharides produced by bifidobacteria” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4946188/

and fragilis fuels colon cancer https://www.nytimes.com/2018/02/01/health/colon-cancer-bacteria.html?ref=todayspaper

“Patients with familial adenomatous polyposis harbor colonic biofilms containing tumorigenic bacteria” http://science.sciencemag.org/content/359/6375/592

the same fragilis is antibiotic resistant Antimicrobial resistance in the Bacteroides fragilis group in faecal samples from patients receiving broad-spectrum antibiotics. https://www.ncbi.nlm.nih.gov/pubmed/28445776

the same fragilis may or may not cause symptoms Dientamoeba fragilis colonization is not associated with gastrointestinal symptoms in children at primary care level. https://www.ncbi.nlm.nih.gov/pubmed/27784723

Dientamoeba fragilis: A Family Cluster of Disease Associated With Marked Peripheral Eosinophilia https://academic.oup.com/cid/article/57/6/845/329548

This is one of the best articles highlighting this microbe ( w/ some contrary evidence from northern Europe). “Dientamoeba fragilis, the Neglected Trichomonad of the Human Bowel” https://cmr.asm.org/content/29/3/553