Does Kefir Help Treat C. diff?
Kefir, a fermented milk probiotic product, has only anecdotal case series evidence suggesting potential benefit for recurrent C. difficile infection when combined with tapered antibiotic therapy, but it is not recommended as standard treatment and should not replace proven therapies like vancomycin, fidaxomicin, or fecal microbiota transplantation. 1
Evidence for Kefir in C. diff Treatment
The only published evidence for kefir in treating C. difficile infection consists of a single case series that suggested daily kefir administration with staggered, tapered doses of vancomycin or metronidazole may be beneficial for recurrent CDI 1. However, this represents the lowest level of evidence—anecdotal case reports without controlled comparison groups.
Current Standard Treatment Recommendations
First-Line Antibiotic Therapy
For initial C. difficile infection, the evidence-based approach prioritizes:
- Oral vancomycin 125 mg four times daily for 10 days is recommended as first-line therapy regardless of disease severity 2
- Fidaxomicin 200 mg twice daily for 10 days is an effective alternative with lower recurrence rates 2, 3
- Metronidazole 500 mg three times daily for 10 days should be limited to non-severe initial episodes only, as it is considered inferior with increasing treatment failures 1, 2, 4
Recurrent C. diff Infection
For patients with recurrent disease (where kefir has been anecdotally suggested):
- Vancomycin tapered and pulsed regimen (125 mg four times daily for 10-14 days, then twice daily for 7 days, then once daily for 7 days, then every 2-3 days for 2-8 weeks) is recommended for second and subsequent recurrences 2
- Fecal microbiota transplantation (FMT) achieves 90-94% symptom resolution in recurrent CDI and is the most effective option after multiple recurrences 1
Probiotics in C. diff: What the Guidelines Say
The American Gastroenterological Association (AGA) makes no recommendations for the use of probiotics in the treatment of C. difficile infection 1. This is a critical distinction—probiotics may have a role in prevention but not in treatment.
Evidence Quality Issues
The evidence for probiotics as adjunctive treatment is problematic:
- Only 5 placebo-controlled RCTs exist, testing 4 different probiotic formulations with heterogeneous study designs 1
- All studies had uncertain or high risk of bias regarding blinding and selective reporting 1
- Data were too heterogeneous to pool for meta-analysis 1
- One probiotic strain (Lactobacillus rhamnosus ATCC 53103) actually increased recurrence of C. difficile infection compared to placebo (RR 2.63) 1
Limited Evidence for Specific Probiotics
The largest study (134 patients) found Saccharomyces boulardii may reduce diarrhea recurrence (RR 0.59), but the quality of evidence was low 1. A European guideline noted that high-dose vancomycin (500 mg four times daily) followed by S. boulardii reduced failure rates from 50% to 17% in one trial, but this had a 22% dropout rate 1.
Critical Clinical Pitfalls
Do not delay or substitute proven therapies with kefir or other probiotics. C. difficile infection causes 29,000 deaths annually in the United States and can progress to fulminant colitis, toxic megacolon, and death 1. The priority must be:
- Immediate appropriate antibiotic therapy based on disease severity 2, 4
- Discontinuation of inciting antibiotics as soon as possible 2
- Early surgical consultation for patients with systemic toxicity or fulminant disease 1, 2
Prevention vs. Treatment Distinction
While the AGA conditionally suggests certain probiotic strains (including S. boulardii) for prevention of C. difficile infection in patients on antibiotics, this is entirely separate from treating active infection 1. The Infectious Diseases Society of America does not recommend probiotics for prevention in routine settings 4.
Bottom Line for Clinical Practice
Kefir lacks rigorous evidence for treating C. difficile infection. Patients with C. diff should receive vancomycin or fidaxomicin as first-line therapy 2, 3, 4. For recurrent disease after appropriate antibiotic courses, fecal microbiota transplantation has proven efficacy with 90%+ cure rates and should be prioritized over unproven interventions like kefir 1, 4.