SIBO Testing with Lactulose

“The findings of the lactulose breath test in irritable bowel syndrome patients have been used to suggest that most patients have small intestinal bacterial overgrowth (SIBO), and this association has spawned the widespread use of antibiotics in IBS. The study by Bratten and colleagues demonstrates that this test does not discriminate between IBS patients and healthy controls when criteria from recent clinical IBS studies are applied. ” [2008]

I recently added some more studies and found that the list of bacteria that will consume lactulose is quite large — with both good and bad listed.

Taxonomy Rank Effect
Bifidobacteriaceae family Increases
Lactobacillaceae family Increases
Streptococcaceae family Increases
Bifidobacterium genus Increases
Lactobacillus genus Increases
Lactobacillus genus Increases
Streptococcus genus Increases
Streptococcus genus Increases
Aerococcus viridans species Increases
Bacteroides fragilis species Increases
Bacteroides ovatus species Increases
Bacteroides thetaiotaomicron species Increases
Bacteroides uniformis species Increases
Bacteroides vulgatus species Increases
Bifidobacterium adolescentis species Increases
Bifidobacterium bifidum species Increases
Enterobacter aerogenes species Increases
Enterococcus faecalis species Increases
Escherichia coli species Increases
Lactobacillus acidophilus species Increases
Lactobacillus brevis species Increases
Lactobacillus casei species Increases
Lactobacillus rhamnosus species Increases
Parabacteroides distasonis species Increases
Peptoclostridium difficile species Increases
Peptostreptococcus anaerobius species Increases
Proteus mirabilis species Increases
Proteus vulgaris species Increases
Streptococcus thermophilus species Increases

Bottom Line

Recently I posted about another probiotic that gave positive lactulose breath test when given to healthy individuals. I look at the list above and see many bacteria that are often in yogurt or available as probiotics.

In short, not only have studies on human discredited this test — but logic also discredit it. It is totally unclear which bacteria is overgrown!