Dietary fructooligosaccharides affect intestinal barrier function in healthy men

Area of Science:

• Human Gut Microbiome Research
• Dietary Fiber Studies
• Gastrointestinal Health

Background:

• Previous rat studies indicated dietary fructooligosaccharides (FOS) promote Salmonella colonization by increasing gut permeability and fecal water cytotoxicity.
• The effects of FOS on human intestinal physiology, particularly in relation to invasive pathogens, remain less understood.

Purpose of the Study:

• To investigate whether fructooligosaccharides (FOS) exert similar effects on human intestinal parameters as observed in rats.
• To assess the impact of FOS consumption on fecal water cytotoxicity, mucin excretion, and intestinal permeability in healthy human subjects.

Main Methods:

• A double-blind, placebo-controlled, crossover study involving 34 healthy men consuming 20g FOS or placebo daily for 2 weeks, with a 2-week washout period.
• Measurements included fecal microbiota, lactic acid, mucin excretion, intestinal permeability marker (chromium EDTA), and gastrointestinal symptom scoring.
• In vitro bioassays assessed fecal water cytotoxicity.

Main Results:

• FOS consumption significantly increased fecal wet weight, beneficial bacteria (bifidobacteria, lactobacilli), and lactic acid production.
• FOS intake led to increased flatulence, bloating, and doubled fecal mucin excretion, indicating mild mucosal irritation.
• Contrary to rat studies, FOS did not alter fecal water cytotoxicity or intestinal permeability in humans.

Conclusions:

• Fructooligosaccharides (FOS) fermentation in humans supports beneficial gut bacteria and produces lactic acid.
• FOS consumption causes mild gastrointestinal symptoms and increased mucin excretion, suggesting a moderate mucosal irritant effect in humans.
• The significant increase in intestinal permeability and fecal water cytotoxicity observed in rats was not replicated in humans.