Study under review: The efficacy and safety of probiotics in patients with irritable bowel syndrome: Evidence based on 35 randomized controlled trials.
Irritable bowel syndrome (IBS) is a functional disorder of the gastrointestinal system affecting approximately 5-20% of the general population. People with IBS experience abdominal discomfort and/or a change in the number of bowel movements and stool consistency in response to a variety of triggers, such as diet changes, infection, or stress. IBS is not defined by an anatomical abnormality or measurable biomarker in the human body. Rather, it is characterized by its symptoms, clinically diagnosed using the Rome IV criteria, and classified into one of four subtypes depending on which symptoms are predominant: diarrhea (IBS-D), constipation (IBS-C), mixed diarrhea and constipation (IBS-M), or undetermined/unspecified (IBS-U). These subtypes are shown in Figure 1. Additional symptoms include bloating, urgency, and flatulence. Although not life-threatening, the discomfort and embarrassment associated with IBS greatly impacts quality of life, resulting in missed workdays, reduced work productivity, and social anxiety.
The pathophysiology of IBS is not yet fully understood, and identifying the root cause for each person can be difficult. Theories range from impaired brain-gut interactions and gastric motility, to stress, dietary allergies/intolerances, intestinal infections, alterations in gut immune activation, and intestinal permeability. In the absence of a proper understanding of the underlying cause, treatment is focused primarily on relieving symptoms. Therapies include emotional and lifestyle modifications (cognitive behavioral therapy, hypnotherapy, stress management, sleep hygiene), dietary interventions (restrictive or elimination diets, high-fiber intake), and medications (laxatives, anticholinergic agents, anti-diarrheal medications, antidepressants, antibiotics). However, not everyone responds to these treatment modalities, and there is no consistent “cure” for IBS, to date.
In an effort to explore alternative treatment options, research on the role of the gut microbiome in IBS is growing, and some data suggest that alterations in gut bacteria can trigger or exacerbate IBS symptoms. This idea stemmed from observations of IBS occurring after certain types of acute GI infections (post-infectious IBS). When compared to healthy controls, the microbiome of people with IBS often, but not always, shows significant differences in composition, such as a reduction in Bifidobacterium and an imbalanced Firmicutes to Bateroidetes ratio. Thus, probiotics, defined as a “live microorganism that, when administered in adequate amounts, confers a health benefit on the host,” offer promise in effectively treating IBS for some people, and several researchers have explored the effects of probiotic supplementation on the expression of IBS symptoms.
The study under review is a meta-analysis that sought to compile and evaluate all the currently available data on the efficacy and safety of probiotic use in people with IBS, focusing exclusively on randomized controlled trials (RCTs).
Irritable bowel syndrome (IBS) affects up to 20% of the general population and has a significant impact on quality of life. The cause is not yet fully understood, and current treatments are not always effective or tolerable for everyone. Studies suggest the gut microbiome plays a significant role in the manifestation and modulation of IBS, making probiotics a promising option for effective treatment. This meta-analysis of RCTs aimed to examine the efficacy and safety of probiotic use in people with IBS.
Other Articles in Issue #66 (April 2020)
Supercharging muscle protein synthesis through essential amino acids
Adding essential amino acids to whey may boost muscle protein synthesis, but the dose matters!
Mini: Summarizing the evidence on milk consumption and your health
We quickly review the evidence of milk and dairy consumption on various health endpoints — blood pressure, cancer, bone health, heart disease, diabetes, and more.
Can sweet and salty mouth rinses provide a taste of victory?
This study provides a pinch of evidence that mouth rinses could affect performance, but more evidence is needed to sweeten up confidence in this finding.
Deep Dive: Fruit, vegetables, and cardiovascular risk factors
An apple a day probably isn’t enough to keep the cardiologist away, but the evidence suggests that 3-5 servings of fruits and veggies may help a little bit.
Evaluating the differences between big breakfasts and big dinners
More calories are burned after breakfast than after dinner, but does it matter?
Berberine supplementation reduces a major colorectal cancer risk factor
Colorectal cancers are the second-most common cause of cancer death, which makes the results of this large two-year study a pretty big deal if they hold up to replication.
Op-Ed: Science in the 21st Century: Notes from an industry harlot
Stu Phillips drops by to give his perspective on the role of industry funding in modern-day research.