Constipation is usually a disorder of the motor activity of the colon. The importance of the intestinal microbiota for bowel habit and gut function is highlighted by alterations in subjects with constipation, e.g. lower levels of lactobacilli and bifidobacteria (Khalif et al. 2005).
The composition of the microbiota is also associated with motility of the gastrointestinal tract (Barbara et al. 2005). Microbial production of short chain fatty acids and metabolism of bile acids is important for lowering gut pH and stimulating motility.
A review of 21 studies with 2,656 constipated subjects displayed a benefit of probiotics: stool frequency and intestinal transit time was significantly improved by supplementation with lactobacilli or bifidobacteria (Miller et al. 2017).
IBS and constipation studies with L. casei Shirota include human trials and mechanistic studies (Aoki et al. 2014, Cassani et al. 2011, Koebnick et al. 2003, Mazlyn et al. 2013, Sakai et al. 2015, Tsuji et al. 2014). Also relevant are human trials that show L. casei Shirota consumption to be associated with positive effects on stool consistency and transit time (Krammer et al. 2011, Sakai et al. 2011).
Effect on constipation symptoms (adults) - Koebnick et al. (2003) Can J Gastroenterol 17:655-659.
Method: In this double-blind, placebo-controlled, randomised trial conducted in Germany, 70 chronically constipated adults drank one bottle a day of probiotic fermented milk (minimum 6.5 x109 L. casei Shirota) or placebo for four weeks. Efficacy was assessed by a weekly medical examination and patient questionnaire (gastrointestinal symptoms; wellbeing; bowel habit). The severity of constipation, flatulence and bloating was graded as severe, moderately severe, mild, or no symptoms.
Results: Starting from the second week of drinking, a significant improvement of certain constipation symptoms was observed for those in the probiotic group (all P<0.001).
Study: Constipation - Transit time
Effect on transit time - Krammer et al. (2011) Coloproctology 33:109-113.
Methods: In this double-blind, placebo-controlled trial, 24 patients with chronic constipation (transit time >72h) received a drink containing L. casei Shirota (6.5 x 109 CFU) or placebo, daily for 4-weeks. A Hinton Test with radiopaque markers was performed on all participants at baseline and after the intervention to assess the colonic transit time. General gastrointestinal symptoms were recorded using a weekly questionnaire.
Results: L. casei Shirota led to a significant acceleration of the colonic transit time from 95.6 to 76.5 hours (P=0.05). This effect was most marked in the sigmoid and rectal transit times (P<0.007). The change in transit time from 98.8 to 87.1 hours in the placebo group was not statistically significant (P=0.282).
Conclusion: L. casei Shirota can shorten the colonic transit time in patients with slow transit constipation.
Besides the frequency of bowel movements and increasing faecal bulk, stool consistency is an important part of healthy bowel habits. Stool consistency is mainly determined by the faecal water content. Harder and dryer stools are often perceived as gastrointestinal discomfort without necessarily being associated with constipation or IBS.
Interestingly, stool consistency strongly associates with known microbiome markers. For example, microbial diversity in the gut decreases with higher Bristol Stool Scale scores (6-7) –indicating a more liquid stool. Furthermore, the different enterotypes are distinctly assigned to Bristol Stool Scale ranges (Vandeputte et al. 2016).
Studies with L. casei Shirota investigate human bowel habits including parameters like stool frequency, transit time and stool consistency (Krammer et al. 2011, Sakai et al. 2011, Tilley et al. 2014).
Study: Constipation - Stool consistency
Effect on stool consistency - Tilley et al. (2014) Int J Probiotics Prebiotics 9(1/2):23-30.
Method: In this double-blind, placebo-controlled randomised study, 120 adults suffering from mild constipation (defined as four or less complete bowel movements per week ) were assigned a daily drink with L. casei Shirota (6.5 x109 CFU) or placebo, for 4-weeks. Stool consistency was analysed using a patient questionnaire based on the visual Bristol Stool Scale.
Results: Compared to placebo, subjects taking L. casei Shirota experienced a significant improvement in stool consistency; the stools became softer. Both groups showed an improvement in defecation frequency.