PracticeUpdate.com
RESEARCH · August 06, 2014
TAKE-HOME MESSAGE
- In this review and meta-analysis, 14 records, which included 1182 patients with functional constipation, were evaluated retrospectively to determine the effect of probiotics on gut transit time, stool output, and constipation symptoms. The authors found that both Bifidobacterium lactis and Lactobacillus casei Shirota probiotics reduced whole-gut transit time by 12.4 hours. Stool frequency and consistency were significantly increased with use of B. lactis but not L. casei Shirota.
- The authors conclude that probiotics, and B. lactis in particular, improve whole-gut transit time, stool frequency, and stool consistency. They note that a drawback of this study is the high heterogeneity and risk bias of the data and advocate for adequately powered randomized clinical trials to determine the most effective probiotic regimens.
Expert Comment
Primary Care
David Rakel MD, FAAFP
Probiotics for constipation
Probiotics have traditionally been thought to be most beneficial for reducing the duration and severity of diarrhea, but this meta-analysis shows benefit for constipation as well. The average time it takes a meal to go from the mouth to the rectum is 30 to 40 hours. In those who have trouble with constipation, this time often exceeds 72 hours. This study showed that probiotics can reduce this time by 12.4 hours and increase the number of bowel movements by 1.3 per week. This is about half as potent as stimulant and osmotic laxatives. The probiotics were found to have side effects no worse than placebo, and patient compliance in these studies was high.
The probiotic that was associated with the most regularity was Bifidobacterium lactus. This was found to be more beneficial than Lactobacillus. If you recommend probiotics for constipation, remember the “B” genus: “Bifidobacterium for bowel movements.” Of note, two of the authors received training funding and two received grant support from Nestec, the research arm of Nestle, which produces probiotics.
The exact mechanism of action is unknown, but is thought be related to the ability of the probiotic to interact with fiber to create short-chain fatty acids (eg, butyric acid and lactate) that lower the pH of the gut lumen, stimulating peristalsis.
Before starting your constipated patient on long-term osmotic or stimulant laxatives, consider the following recommendations:
- Regular movement and exercise
- Maintaining hydration (2–3 L/day or enough to urinate five times daily)
- Eating a breakfast containing 20 g fiber each morning. An example includes: 1/2 cup bran (10 g), three dried figs (10 g), made palatable with soy/almond milk (1 g fiber), 1 tbsp brown sugar for taste, and 1 tbsp of cinnamon (slows absorption of sugar).
- Eating other high-fiber foods, including one apple or pear (5 g), 1 cup raspberries (8 g), 1 cup raisin bran (5 g), two Brazil nuts (2.5 g), 23 almonds (3.5 g), 1 cup peas (16 g), 1 cup black beans (15 g), one artichoke (10 g), and 1 cup broccoli (5 g).
- Adding a viscous or soluble fiber if your patient doesn’t get enough fiber. Examples include: 1 to 3 tsp psyllium in 8 to 10 oz of water one to two times daily; 1 tbsp ground flax seed sprinkled over salads or placed in a smoothie twice daily. Telling your patient to be sure to drink enough water with this fiber; too little water can worsen constipation.
- Adding a probiotic that contains B. lactus at a dose of 1 capsule (109 colony-forming units) twice daily.
ABSTRACT
BACKGROUND
Functional constipation is a prevalent, burdensome gastrointestinal disorder whose treatment remains challenging. Probiotics have been increasingly investigated in its management.
OBJECTIVE
The aim was to investigate the effect of probiotics on gut transit time, stool output, and constipation symptoms in adults with functional constipation via a systematic review and meta-analysis of randomized controlled trials (RCTs).
DESIGN
Studies were identified by searching 4 electronic databases, back-searching reference lists, contacting authors, and hand-searching abstracts. RCTs that reported administration of probiotics in adults with functional constipation were included. Two reviewers independently performed the screening, data extraction, and bias assessment. Outcome data were synthesized by using weighted mean differences (WMDs) or standardized mean differences (SMDs) with the use of a random-effects model.
RESULTS
A total of 660 records were identified of which 14 were eligible (1182 patients). Overall, probiotics significantly reduced whole gut transit time by 12.4 h (95% CI: -22.3, -2.5 h) and increased stool frequency by 1.3 bowel movements/wk (95% CI: 0.7, 1.9 bowel movements/wk), and this was significant for Bifidobacterium lactis (WMD: 1.5 bowel movements/wk; 95% CI: 0.7, 2.3 bowel movements/wk) but not for Lactobacillus casei Shirota (WMD: -0.2 bowel movements/wk; 95% CI: -0.8, 0.9 bowel movements/wk). Probiotics improved stool consistency (SMD: +0.55; 95% CI: 0.27, 0.82), and this was significant for B. lactis (SMD: +0.46; 95% CI: 0.08, 0.85) but not for L. casei Shirota (SMD: +0.26; 95% CI: -0.30, 0.82). No serious adverse events were reported. Attrition and reporting bias were high, whereas selection bias was unclear due to inadequate reporting.
CONCLUSIONS
Probiotics may improve whole gut transit time, stool frequency, and stool consistency, with subgroup analysis indicating beneficial effects of B. lactis in particular. However, caution is needed with the interpretation of these data due to their high heterogeneity and risk of bias. Adequately powered RCTs are required to better determine the species or strains, doses, and duration of use of probiotics that are most efficacious.
The American Journal of Clinical Nutrition
The Effect of Probiotics on Functional Constipation in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials