Reviewed by: HU Medical Review Board | Last reviewed: March 2023 | Last updated: April 2023
While experts are unsure on the underlying cause of IBS, some believe it is a combination of several factors, including, but not limited to, bacterial overgrowth, microscopic inflammation, hypersensitivity, and alterations in gut motility (or movement of the muscles in the intestinal tract).1,2
In order for our gut to function properly, we need a specific balance of “good” bacteria living in our gastrointestinal tract. These bacteria help boost our immune system, aid in nutrient and drug processing and play a role in maintaining the function of our intestinal barriers.3,4
Some experts believe that a disruption in the normal human gut-bacteria relationship may contribute to the development and symptoms of IBS.4,5 Specifically, several studies have shown that individuals with IBS may have fewer numbers of lactobacilli and bifidobacteria (two health-promoting bacterial organisms).1
What are prebiotics?
In addition to using IBS-specific medications, some individuals may also try alternative or complementary therapies in an effort to control symptoms. Common alternative therapies for IBS are probiotics and prebiotics. Probiotics are supplements that contain “good” bacteria, like lactobacilli and bifidobacteria species.1 These supplements deliver health-promoting bacteria directly to the gastrointestinal system.
Prebiotics, on the other hand, can be described as the food source for these bacteria. Prebiotics can be taken as supplements, or can be obtained from some of the foods we eat. They are fermentable and non-digestible by the human body, and therefore, can be used by our health-promoting gut bacteria to enhance growth and activity.
Commonly used and discussed prebiotics include oligofructose, fructans (inulin and fructooligosaccharides), galactooligosaccharides, and resistant starch.1,2,6 These are all carbohydrates that the human body can’t break down, but bacteria can. When prebiotics and probiotics are combined together, they are called synbiotics.
Research on prebiotics in the treatment of IBS
Like many complementary and alternative therapies, there is no strong scientific consensus on the effectiveness of prebiotics in treating IBS or its symptoms. Studies that have been completed thus far have provided mixed results. Currently, there is much more research that exists surrounding probiotics and their potential health benefits than prebiotics or synbiotics. Some studies have found that prebiotics may have no effect on IBS symptoms, or may even worsen symptoms for some individuals.1
Results from other studies have found that some symptoms may improve with prebiotic therapy while other symptoms may be unchanged or worsen at the same time. Symptom changes or improvements may vary based on the type of prebiotic taken and the dosage administered. As an example, lower doses of prebiotics may be helpful in alleviating symptoms like flatulence and bloating, while at high doses, these symptoms may be worsened as the bacteria continue to utilize the prebiotics at higher rates, creating more gastrointestinal disruption.1,5
One relatively recent study on mice suggested that prebiotic administration prior to the initial development of IBS and its symptoms may prevent the onset of the condition in the first place.4 However, further evidence is needed to strengthen this association.
Although a greater number of studies are arising that focus on our gut bacteria and its relationship to our overall health, data on prebiotics and synbiotics are lacking and mixed at this time. Much more investigation is needed to determine the relationship between prebiotics and IBS symptom management.2
Sources of prebiotics
Prebiotics can be taken in supplement form, or can be obtained in foods that we eat. Examples of foods that contain prebiotics may include:
- Whole grains
- Legumes (beans, lentils, chickpeas)
- Chicory root
When considering prebiotics
It is important to note that prebiotics are FODMAPs, which may be restricted in individuals following a low FODMAP diet to help improve symptoms.8 However, long-term low FODMAP diets may not be recommended for individuals with IBS. It’s important to consult your doctor or a nutritionist before trying any new dietary changes or supplements.
Additionally, prebiotics are not considered pharmaceutical drugs and are not regulated by the United States FDA (Food and Drug Administration). This means, there can be great variability in what is actually contained in each prebiotic supplement based on what brand it is. This is another reason to check in with your doctor before trying any new dietary change or supplement, especially if you are unsure how it may affect you and your body.
Other treatment options
In addition to prebiotics, there are other complementary and alternative treatment options that may be utilized by individuals with IBS alongside a traditional, FDA-approved medication regimen. These include probiotics, exercising, and increasing fiber intake or making other dietary changes. Some trial and error may be required to find the best balance for you.
Before beginning treatment for IBS, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you take. This includes over-the-counter drugs.