One of the largest randomized controlled trials using probiotics as an intervention was recently published in the British Journal of Nutrition (Eskesen et al. 2015). The study was on 1248 healthy subjects with low defecation frequency and abdominal discomfort and tested the effect of Bifidobacterium animalis subsp. lactis, BB-12 on defecation frequency and global relief of gastrointestinal symptoms. The strain BB-12 is the most broadly studied probiotic Bifidobacterium strain.
The study details:
- N=1248 healthy 18–70-year-old subjects, with a low defecation frequency (2–4 d/week) and complaints of general abdominal discomfort, but without diagnosed GI disease or syndrome
- 2-week run-in period, 4 week treatment
- This was a dose study. Three-arms: 1×109 cfu, 1×1010 cfu and inactive placebo, in capsules
- Primary endpoints: defecation frequency and gastrointestinal well-being
- Secondary endpoints: symptom severity scores for abdominal pain and bloating
- The trial was registered through the International Standard Registered Clinical study registry
The study found that the probiotic improved defecation frequency but there were no differences for GI well-being. No dose effect was found – 1 billion BB-12 were as effective as 10 billion – suggesting a ceiling effect was observed.
This study points to difficulty in conducting research on probiotics for digestive health destined for consumption by the general population. First, subjects being recruited are healthy, with some digestive complaints, but not disease. Such digestive complaints are likely rooted in different etiologies, resulting in an unavoidable heterogeneity of the study population. Second, there is a high placebo rate; to see a measurable effect a product needs to exceed the placebo rate. Third, there are likely several factors that impact whether a subject will respond to a probiotic, such as the subject’s colonizing microbiota, diet and underlying cause of symptoms. Lastly, probiotics by nature are complicated. Probiotics are living organisms, not single molecule drugs. They have the potential to affect many host systems as they traverse the intestinal tract, including immune system, central nervous system, epithelial barrier, luminal metabolism, colonizing host microbiota and more. Such factors make these studies challenging.
In short, this study was a well-conducted effort to determine the impact of a probiotic on GI function in healthy subjects. One billion Bifidobacterium animalis subsp. lactis BB-12 per day is a safe and effective means to speed up defecation frequency for people with this problem.
Eskesen D, Jespersen L, Michelsen B, Whorwell PJ, Müller-Lissner S, Morberg CM. Effect of the probiotic strain Bifidobacterium animalis subsp. lactis, BB-12®, on defecation frequency in healthy subjects with low defecation frequency and abdominal discomfort: a randomised, double-blind, placebo-controlled, parallel-group trial. Br J Nutr. 2015 Sep 18:1-9.