Some more thoughts looking at the 10 billion or more per day dosage.
You can also see they can recover this strain from tissue biopsies, not just the feces.
They’re basically saying 1 billion per day at 8 weeks might not be enough for effect.
Fecal excretion of Bifidobacterium infantis 35624 and changes in fecal microbiota after eight weeks of oral supplementation with encapsulated probiotic
using B. infantis 35624 transformed with a rifampicin resistance gene as a marker for enumeration, the investigators demonstrated that the strain had established itself in the colon of these patients, reaching levels of 105–108 cfu, depending on the individual; the strain could be recovered from fecal samples and colon biopsies.
Consequently, our study does not allow firm conclusions about the impact of B. infantis 35624 supplementation on the GI tract microbiota. However, exploratory studies from our laboratory, which characterized fecal microbiota using terminal restriction fragment polymorphism (t-RFLP) analysis of microbial DNA, showed that controlled daily administration of 1010 cfu B. infantis 35624 in milk for three weeks helped normalize the intestinal microbiota. The analysis of fecal samples from 24 subjects (13 with IBS and 11 controls) revealed 3 DNA fragments associated exclusively with IBS, 29 fragments that differed in proportion between IBS patients and healthy controls prior to treatment and a probiotic-associated shift to equivalent proportions of 16 of these 29 fragments in the microbiota of both groups (unpublished data). Hence, more robust and comprehensive surveys (and, possibly, longer interventions) may be needed to detect potential changes in GI tract microbiota associated with B . infantis 35624 supplementation
We conclude that further fecal microbiota studies with more comprehensive microbial surveys and additional doses of B. infantis 35624 administered for longer durations are needed to further explore the role of the intestinal microbiota composition and metabolic processes
I think ive posted this one before,