Study under review: Does a diet low in FODMAPs reduce symptoms associated with functional gastrointestinal disorders? A comprehensive systematic review and metaanalysis
Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder that affects approximately 11% of the global population. It is associated with abdominal pain, bloating, excessive flatulence, and altered bowel habits, severely lowering a person’s quality of life. Functional gastrointestinal disorders like IBS are not caused by structural abnormalities such as ulcers or tumors. Rather, they occur as a result of an abnormally functioning GI tract. This makes it difficult to accurately diagnose a person because no biomarker can indicate whether or not someone is suffering from IBS. Thus, clinicians have to rely on the reports of patients and on a set of criteria that have evolved over time for diagnosis.
Although the cause of IBS is still not well understood, researchers have put forth several hypotheses. Some of these theories include infections of the GI tract, psychological stress, abnormalities in gut motility, and gut-brain axis problems. Unfortunately, no cures currently exist for IBS. It is managed through various treatments such as 5-HT agonists/antagonists, antispasmodics, and antidepressants. These drugs can improve primary symptoms in some people, but they are unable to fully resolve disorders like IBS that are characterized by multiple symptoms. In addition to their limited use, there are several side effects associated with these drugs, so long-term use is not ideal.
As a result of these issues, researchers have investigated several alternative treatments as potential treatments for IBS. Patients suffering from IBS often report that particular foods worsen their symptoms more than others. Therefore, researchers have investigated various dietary interventions.
Dietary interventions that restrict specific food components, such as low-FODMAP diets, have been explored in several trials. FODMAP is an acronym that stands for "Fermentable, Oligo-saccharides, Di-saccharides, Mono-saccharides, and Polyols." These are short-chain carbohydrates that are poorly digested and absorbed in the small intestine. As a consequence, they travel to the large intestine, where they are fermented by the bacteria that colonize it. This breakdown of carbohydrates by bacteria results in the formation of gasses such as hydrogen and methane in all individuals. However, this phenomenon seems to be excessive in IBS sufferers. Therefore, restricting foods that are rich in these short-chain carbohydrates (some of these are listed in Figure 1) can potentially alleviate many of the symptoms prominent in people with IBS.
Source: The Monash University Low FODMAP diet
A previous systematic review conducted in 2015 showed that a low-FODMAP diet was somewhat effective in reducing the severity of symptoms associated with IBS. Six studies were included in that review and of those six, three were randomized controlled trials. The authors concluded that although a low-FODMAP was somewhat effective in treating IBS symptoms, more controlled trials with longer durations were needed to gauge the efficacy and safety of a low-FODMAP diet in treating IBS symptoms. The current study extends upon that review with further research, and also performs a meta-analysis to quantitatively summarize the findings.
Irritable bowel syndrome is a functional gastrointestinal disorder associated with abdominal pain, distension, and altered bowel habits. It is theorized to have a variety of causes. It is currently considered incurable by most medical practitioners, and is most commonly managed through the use of pharmaceuticals. Several alternative treatments have been explored as a result of this and one of these treatments, a low-FODMAP diet, has shown some effectiveness in reducing the severity of the symptoms associated with IBS.
Other Articles in Issue #26 (December 2016)
Gelatin + vitamin C + exercise = joint benefits?
Exercise can help remodel soft tissue, including the collagen in joint tissue. Researchers already knew that vitamin C and gelatin are involved in collagen formation, and here they are tested along with exercise in a randomized trial.
What happens to diets when you control food quality?
Dieters often control their intake of either carbs or fat. But when dieting, the overall quality of food you eat can also change. Do low-fat and low-carb diet effects differ, even if you control for food quality?
Can diet soda ruin your diet?
Evidence is still quite mixed when it comes to diet soda effects on weight loss (or gain). Observational evidence often contradicts with trial evidence. This study adds to the body of evidence, specifically on those with type 2 diabetes.
Interview: Dr. Taylor Wallace, PhD
Dr. Wallace has done research in a variety of areas, including anthocyanins in plants. Here, we ask him about topics ranging from food additives to supplement side effects.
Can probiotics help with Alzheimer’s?
With an aging population, more and more people know someone with Alzheimer’s. As a disease of the brain, symptoms could be helped by supporting an organ that plays directly into brain health: the gut.
Curcumin for a clear nose
There are two types of people in the world: those who get seasonal allergies, and those who don’t. If you sneeze and wheeze, this trial on curcumin for allergic rhinitis provides must-read information.
Interview: Grant Tinsley, PhD
Remember that neat intermittent fasting study in the previous issue of NERD? We were lucky enough to interview one of the study authors, Grant Tinsley.