Study under review: Systematic review with metaanalysis: the efficacy of probiotics in inflammatory bowel disease.
Inflammatory bowel disease (IBD) is a collective term that includes both Crohn’s disease (CD) and ulcerative colitis (UC). The differences between these two types of IBD can be seen in Figure 1. IBD affects as many as 450 people out of every 100,000 in the United States. While the cause of IBD and its rising numbers is still unclear, it is thought to be due to complex interactions between genetic, immune, and environmental factors. Recent evidence also suggests that the gut microbiome may be of particular importance.
Typical changes in the gut microbiota seen in IBD include an increase in the abundance of bacterial species associated with increased inflammation, a decrease in bacterial species linked to reduced inflammation, and a decrease in the diversity of bacteria. Differences have also been found between the bacteria found in inflamed and noninflamed parts of the gut in people with IBD. The use of antibiotics, which can disrupt the normal bacteria in the gut, has been associated with an increased risk of developing CD. These separate lines of evidence seem to point gut bacteria playing a role in IBD.
Given this possible role, it’s plausible that the disease could be mitigated with probiotics. Probiotics are live microorganisms, usually either bacteria or yeasts, that can provide health benefits when taken in large enough amounts. In laboratory studies using a mouse model of IBD, probiotics have been shown to produce anti-inflammatory effects and improve the integrity of the gut wall, which suggests potential for the treatment for IBD in humans. However, the results of clinical trials using probiotics to treat IBD have so far been mixed, with some studies showing a benefit and others reporting no effect. This may be the result of different bacterial species or strains in the probiotics used, other differences in the way the studies were carried out, or random chance.
Several meta-analyses have now attempted to pool the evidence from all the published clinical trials examining the benefit of probiotics on people with IBD. However, there were issues with many of these. Some have combined data from studies using probiotics and synbiotics, which are a combination of probiotic bacteria and prebiotic fiber, making it harder to separate out the effects of probiotics alone. Others used data from both children and adults, which makes it hard to see the effects in children or adults on their own. Furthermore, recent research examining the quality of meta-analyses that have investigated the effects of probiotics in IBD found that many have been of relatively low quality, and that better quality meta-analyses were required.
The study under review is a systematic review and meta-analysis of RCTs investigating the benefit of probiotics in different subgroups of people with IBD. Where possible, the authors sought to identify the effect of individual probiotic preparations in inducing remission in active Crohn’s disease and ulcerative colitis. They also examined the ability of probiotics to maintain remission for participants with inactive disease, and prevent relapse of CD after surgery carried out to treat the disease.
Inflammatory bowel disease (IBD), an umbrella term which includes both Crohn’s disease (CD) and ulcerative colitis (UC), is an increasingly common disease associated with changes in the microbiota and immune system of the gut. With their ability to modulate the intestinal microbiome and downstream effects on the immune system, probiotics have the potential to benefit patients with IBD. However, the results of pertinent randomized controlled trials (RCTs) have been mixed. The study at hand is a systematic review and meta-analysis of all the currently available RCTs assessing the effectiveness of probiotics in adult patients with IBD.
Other Articles in Issue #35 (September 2017)
Interview: Brad Dieter, PhD
In this interview, we pick Brad’s brain on a number of topics, including diabetic kidney disease, science writing, and the possibility of nominative determinism involving his last name!
Interview: Margaret Leitch, PhD
In this interview with experimental psychologist Margaret Leitch, we discuss the psychology of weight loss, the utility of statistics for researchers, and maternal nutrition.
Fish Oil Supplementation for Insulin Resistance: Nothing but a Fish Burp?
Fish oil has been studied a lot for numerous health claims, including improving insulin resistance. But quantity does not necessarily equal quality.
Can the Mediterranean Diet curtail inflammation in Type 2 diabetes?
Evidence suggests that the Mediterranean diet can be beneficial for people with diabetes. Those benefits may also extend to inflammation.
Can alpha-lipoic acid supplementation shed some pounds?
The evidence for alpha-lipoic acid's effect on weight loss is conflicting. This meta-analysis casts some light on the issue
A bit of caffeine may help the antidepressants go down
Antidepressants typically take a while to start working. Can caffeine help them kick in faster?
Stepping up weight loss: Can walking help dieters shed fat?
Walking doesn't do much for fat loss on its own. But there's reason to suspect it could boost the benefits of a caloric deficit.