Another meta-analysis of 34 studies (N=4138) also found probiotic therapy can prevent AAD.10 The pooled RR for AAD was 0.53 (95% CI, 0.44-0.63) for patients treated with probiotics compared to placebo, with an NNT of 8 (95% CI, 7-11). 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 (95% CI, 0.20-0.69) and the NNT was 5 (95% CI, 4-10).10 However, the 2013 PLACIDE trial (N=17,420) found no significant decrease in AAD rates in hospitalized patients over age 65 years being treated with antibiotics who received probiotics (RR=1.04; 95% CI, 0.84-1.28).22
Clostridium difficile-associated diarrhea. As we know, antibiotics can disrupt the normal GI flora and permit overgrow 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, 95% CI, 0.24-0.49).12 Adverse events occurred in 9.3% of patients taking probiotics, compared with 12.6% of controls (RR=0.82, 95% CI, 0.65-1.05).12
Conversely, a 2008 review of 4 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; 95% CI, 0.35-0.98).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 over age 65 years; 0.8% of patients who received probiotics developed CDAD, compared to 1.2% in the placebo group (RR=0.71, 95% CI, 0.34-1.47).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 Problems with this treatment include adverse effects such as 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 when treating 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 5 RCTs (N=1307), S. boulardii significantly increased the H. pylori eradication rate when used as an adjunct to triple therapy (RR=1.13; 95% CI, 1.05-1.21) and reduced the rate of treatment-related adverse effects (RR=0.46; 95% CI, 0.3-0.7).13 In a third meta-analysis of 10 trials (N=1469), Lactobacillus supplementation increased H. pylori eradication rates (OR=2.1; 95% CI, 1.4-3.1) while decreasing the overall incidence of adverse effects (OR=0.3; 0.1-0.8).15
For inflammatory bowel disease, probiotics are unlikely to help
Current therapies for Crohn’s disease and ulcerative colitis, such as corticosteroids and other immunosuppressive agents, are effective but have significant adverse events.18 Researchers explored whether probiotics might help treat these diseases by improving immune response, the balance of microbes in the GI tract, and the intestinal barrier.18
Crohn’s disease. In a meta-analysis that was able to identify only one small RCT (N=11), 80% of patients receiving probiotic treatment went into remission, compared to 83% in the placebo group (OR=0.80; 95% CI, 0.04–17.20).16 Researchers concluded there was insufficient evidence for the use of probiotics for inducing remission in Crohn’s disease.
Another meta-analysis of 7 small studies (N=160) found no significant evidence supporting probiotic use for maintaining remission in Crohn’s disease compared with aminosalicylates or azathioprine.17 One small study in this review found there was a benefit to combining S. boulardii with a reduced level of standard maintenance therapy when compared to standard therapy alone, but this difference was not statistically significant.17
Ulcerative colitis. A systematic review of 4 RCTs (N=244) that compared conventional treatment alone to conventional treatment plus probiotics for remission or clinical improvement in patients with active ulcerative colitis found no significant differences between groups.18 Another meta-analysis of 4 studies (N=587) found that compared to placebo or treatment with mesalazine, probiotics had no benefit for maintaining remission in ulcerative colitis.19 The rate of relapse was 40.1% in the probiotics group compared to 34.1% in the mesalazine group. The number of adverse effects was similar in both groups.
