Introduction

Irritable bowel syndrome (IBS) is a common chronic digestive disorder characterized by recurrent abdominal pain and bowel habit changes. Prevalence of IBS is on the rise in the United States, with recent estimates reporting that 6.1% adults struggle with the condition. IBS is a clinical and public health concern because it substantially diminishes quality of life and contributes to work absenteeism, reduced productivity, and considerable healthcare costs. (Dean 2005)(Tetali 2024)

These burdens on quality of life and healthcare systems, coupled with high rates of patient-reported treatment dissatisfaction, highlight the need for accessible and evidence-based approaches that can be integrated into routine clinical care. (Lacy 2024) This protocol summarizes the findings of the Council for Responsible Nutrition’s (CRN’s) Supplements to Savings report to provide a starting foundation for such an approach.

Ingredients

Probiotics 

Dosing: At least one billion colony-forming units (CFU) per day, minimum of four weeks (Zhang 2023) 

Supporting evidence:

• A systematic review and meta-analysis of 43 randomized controlled trials (RCTs) concluded that probiotics effectively improve IBS symptoms; however, no definite conclusions could be drawn on the optimal species and strains. Over 20% more people taking probiotics reported relief of global IBS symptoms, abdominal pain, bloating, and flatulence than those taking a placebo. (Ford 2014)
• According to this more recent systematic review and meta-analysis, probiotics are effective and safe for treating IBS and are correlated with a significant improvement in global IBS symptoms and quality of life compared to placebo. The analysis of 20 studies (3,011 patients) concluded that high-dose probiotics (>10 billion CFU per day) and multi-strain formulations were associated with greater benefit, particularly for abdominal pain and distension. (Yang 2024) 
• In a randomized triple-blind placebo-controlled trial, patients with IBS (n=340) took either one billion or ten billion CFU of Lactobacillus acidophilus NCFM or a placebo daily for 12 weeks. While there were no significant differences in IBS symptom severity scores (IBS-SSS) at the end of the trial between the three groups, a post-hoc analysis did reveal that probiotics at either dose effectively reduced moderate-to-severe abdominal pain compared to the placebo. Pain scores fell by 20.8 ± 22.8, 29.4 ± 17.9, and 31.2 ± 21.9 in the placebo, active low-dose, and active high-dose groups, respectively. (Lyra 2016)
• In this multicenter RCT, 362 patients with IBS were randomized to receive a placebo or encapsulated Bifidobacterium infantis 35624 at a dose of one million, 100 million, or 10 billion CFU per day for four weeks. B. infantis at a dose of 100 million CFU per day was significantly superior to placebo and all other probiotic doses for relieving abdominal pain, bloating, bowel dysfunction, incomplete evacuation, straining, and gas, with improvement in global symptom assessment exceeding placebo by more than 20%. (Whorwell 2006)
• A probiotic mixture containing Lactobacillus rhamnosus GG, L. rhamnosus LC705, B. breve Bb99, and Propionibacterium freudenreichii ssp. shermanii JS (8–9 billion CFU daily with equal amounts of each strain), reduced the total IBS symptom score—covering abdominal pain, distension, flatulence, and borborygmus—by 42% after six months, compared with only a 6% reduction in the placebo group. The trial included 103 patients who met Rome I or II diagnostic criteria for IBS. (Kajander 2005)
• Female patients with diarrhea-predominant IBS (IBS-D) and constipation-predominant IBS (IBS-C) (n=113) experienced improvements in quality of life, as well as stool frequency and consistency, after 12 weeks of daily probiotic therapy. The intervention provided 50 billion CFU daily, consisting of live Lactobacillus acidophilus CL1285, L. casei LBC80R, and L. rhamnosus CLR2. (Preston 2018) 

 

Probiotics in the Fullscript catalog