PROBIOTICS MAY HELP WITH SOME TYPES OF DIARRHEA
Acute infectious diarrhea. Viruses, bacteria, and parasites cause acute infectious diarrhea, and probiotics are thought to act against these pathogens by competing for available nutrients and pattern-recognition receptors in the GI endothelium, acidifying the local environment, and increasing immune responses within the GI tract. In a meta-analysis of 63 studies (N = 8,014) that used multiple strains and dosages of probiotics, investigators found probiotics shortened the duration of acute infectious diarrhea by approximately 24 h.7 Probiotics also reduced both the risk for diarrhea lasting longer than four days (relative risk [RR], 0.41) and stool frequency on day 2 of illness (mean difference of 0.80 stools).
Traveler’s diarrhea. The incidence of traveler’s diarrhea is > 50% for travel to high-risk areas such as the Middle East, North Africa, Latin America, and Southeast Asia, and 5% to 10% when traveling to areas such as North America, Northern Europe, the United Kingdom, Australia, and New Zealand.8 Traveler’s diarrhea may be caused by ingesting food and liquids contaminated with fecal material. Symptoms include diarrhea, cramps, and nausea that, if untreated, typically last from two to six days but can last for as long as a month.8
In a meta-analysis of 12 studies (N = 5,171) that evaluated various probiotic strains, researchers found probiotics effectively prevented traveler’s diarrhea in US and European travelers who visited a variety of vacation spots (pooled RR, 0.85).8 No serious adverse events were reported.
Radiation-induced diarrhea. Radiation treatments to the abdomen and pelvis can damage the lower GI tract and cause diarrhea. The pooled results from a meta-analysis that included six studies (N = 1,449) significantly favored the use of probiotics over placebo for decreasing the incidence of radiation-induced diarrhea (odds ratio [OR], 0.44).9 Probiotic use also was associated with decreased loperamide use (OR, 0.29) and decreased incidence of watery stools (OR, 0.36), but these outcomes did not reach statistical significance.
Antibiotic-associated diarrhea. Antibiotic use has long been associated with the development of diarrheal illness, sometimes due to the acceleration of GI motility (eg, erythromycin) or by causing osmotic diarrhea by decreasing GI bacteria that assist in carbohydrate breakdown.11 A meta-analysis that evaluated 63 randomized controlled trials (RCTs) (N = 11,811) showed that probiotics are effective for treating and preventing antibiotic-associated diarrhea (AAD).1 There was a statistically significant reduction in AAD among patients who received probiotics (RR, 0.58; number needed to treat [NNT], 13). Most of the studies in this meta-analysis used a Lactobacillus probiotic alone or in combination with another probiotic. Researchers did not analyze whether the efficacy varied by patient population, probiotic used, causative antibiotic, or duration of treatment.1 Another meta-analysis of 34 studies (N = 4,138) also found probiotic therapy can prevent AAD.10 The pooled RR for AAD was 0.53 for patients treated with probiotics compared to placebo, with an NNT of 8. The effects remained significant when results were grouped by probiotic species, patient age, and duration of antibiotic treatment. Among a subgroup of patients in this meta-analysis who were being treated for Helicobacter pylori, the pooled RR of AAD was 0.37 and the NNT was 5.10 However, the 2013 PLACIDE trial (N = 17,420) found no significant decrease in AAD rates in hospitalized patients older than 65 being treated with antibiotics who received probiotics (RR, 1.04).22
Clostridium difficile–associated diarrhea. As we know, antibiotics can disrupt the normal GI flora and permit overgrowth of Clostridium difficile, which can result in C difficile–associated diarrhea (CDAD).12 This can occur with oral, parenteral, and even topical antibiotics.11 Researchers have investigated whether probiotics can prevent this opportunistic C difficile overgrowth.
A 2012 meta-analysis of 20 trials (N = 38,180) found probiotic prophylaxis prevented CDAD in both inpatients and outpatients while not increasing the incidence of significant adverse effects.12 Probiotics decreased the incidence of CDAD by 66% (pooled RR, 0.34).12 Adverse events occurred in 9.3% of patients taking probiotics, compared with 12.6% of controls (RR, 0.82).12
Conversely, a 2008 review of four studies (N = 336) concluded there is insufficient evidence for using probiotics to treat CDAD, either as monotherapy or adjunct therapy.11 One trial in this meta-analysis (N = 124) found patients who received the probiotic Saccharomyces boulardii in addition to antibiotic therapy were significantly less likely to experience CDAD recurrence than those who received placebo (RR, 0.59).11 However, this benefit was not found in the other trials in this meta-analysis.11
The PLACIDE trial found probiotics did not prevent CDAD in hospitalized patients older than 65; 0.8% of patients who received probiotics developed CDAD, compared to 1.2% in the placebo group (RR, 0.71).22
Helicobacter pylori infection. The triple-therapy regimen of a proton pump inhibitor plus the antibiotics clarithromycin and amoxicillin is the recommended treatment for H pylori infection.13 Associated adverse effects include diarrhea and decreased eradication rates, in part due to antibiotic resistance. Certain Lactobacillus species have been shown to inhibit or kill H pylori in vitro,13 and evidence from several meta-analyses suggests probiotics should be an adjunct therapy for the treatment of H pylori.
In a meta-analysis of 10 RCTs (N = 963), fermented milk-based probiotics improved H pylori eradication rates by 5% to 15%.14 In another meta-analysis that evaluated five RCTs (N = 1,307), S boulardii significantly increased the H pylori eradication rate when used as an adjunct to triple therapy (RR, 1.13) and reduced the rate of treatment related adverse effects (RR, 0.46).13 In a third meta-analysis of 10 trials (N = 1,469), Lactobacillus supplementation increased H pylori eradication rates (OR, 2.1) while decreasing the overall incidence of adverse effects (OR, 0.3).15
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