Nutrition and wellness, with the sources attached
Whether a probiotic turns up in stool depends on the strain, except above 10 billion live bacteria a day, when every strain was recovered. The trials that found benefit did not need the bacteria to stay.
Fiber's benefit rests on studies covering seventeen million people and peaks between 25 and 29 grams a day. Probiotic evidence is a set of small, strain-specific trials.
The band where risk fell furthest was 25 to 29 g a day, and what mattered was the total. Which kind of fiber, the soluble and insoluble split printed on the label, barely predicted anything.
Inulin and galacto-oligosaccharides feed bacteria you already have, and about 2.4 grams a day tripled Bifidobacterium in one trial in children. The gas some people get is the same reaction.
Two uses hold up in the trials: diarrhea while you are on antibiotics, and the C. difficile infection that can follow. In children on antibiotics, the dose mattered more than the strain name on the front of the box.
