A new study has shown that a specialised IBS diet plan that avoids certain types of food and often excludes gluten is not as necessary as previously believed.
IBS (irritable bowel syndrome) affects around 3-5% of the world’s population and involves symptoms such as stomach pain and constipation. However, a specialised IBS diet plan is often prescribed to reduce these symptoms.
Researchers from Chalmers University of Technology and Uppsala University in Sweden have found no correlation between high gluten intake and increased IBS symptoms. The researchers did find that a certain type of carbohydrate called ‘fodmaps’ can aggravate intestinal problems; however, the overall results indicate that they also have less influence than previously thought.
Is an IBS diet plan still beneficial?
The new study included 110 people with IBS, and the researchers examined how people were affected by serving them rice puddings prepared in different ways to mimic the IBS triggers. The first rice pudding variety was rich in gluten, and the other one contained large amounts of the carbohydrate of the fodmap variety, which is fermentable carbohydrates.
Many foods are rich in fodmaps, including dairy products, types of bread and certain fruits and vegetables. Additionally, the researchers created a neutral rice pudding as a placebo that would be suitable for an IBS diet plan.
Participants ate the rice puddings rich in fodmaps, gluten, and the IBS diet plan friendly version with no aggravating ingredients, in a random order, for one week per category. The study was double-blind, meaning neither the participants nor researchers knew who ate which pudding and when.
“Diet studies are difficult to conduct double-blind, as it can often be obvious to the participants what they are eating. This is a big obstacle, as the knowledge that something has been added to or removed from the diet can affect the result. The fact that we succeeded in creating diets that were completely blind, together with a large number of participants, makes our study unique,” explained Elise Nordin, PhD student in Food Science at Chalmers and lead author of the scientific article, published in the American Journal of Clinical Nutrition.
The subjects’ gastrointestinal systems were provoked through high doses (1.5 times daily intake in a normal population) of fodmaps and gluten. The fodmaps aggravated the symptoms, but not to the extent that the researchers had expected based on results from previous studies. Gluten, on the other hand, was found to have no measurable negative effect on the subjects’ perceived symptoms.
“Our results are important and indicate that the psychological factor is probably very important. IBS has previously been shown to be linked to mental health. Simply the awareness that one is being tested in a study can reduce the burden of symptoms,” said Per Hellström, Professor of Gastroenterology at Uppsala University who held medical responsibility for the study.
Distinguishing between the effect of gluten and fodmaps
In previous studies, researchers have mainly excluded fodmaps from the subjects’ diets, and this has shown a clear reduction in IBS symptoms. However, these studies have had a few participants and have not been conducted double-blind, making it difficult to evaluate the results objectively.
Many patients following an IBS diet plan excluded gluten from their food intake, despite the lack of scientific evidence. Results from previous research are inconsistent. Foods rich in gluten, such as bread, are often rich in fodmaps. One theory has highlighted that the fodmaps in these foods, not gluten, cause IBS symptoms. This shows the importance of studies for separating the effect of fodmaps and gluten.
Examining how the diet can be individually adapted
The new study is part of a larger project in which the researchers are looking for biomarkers in the intestinal flora or in the blood to predict health outcomes. The researchers wanted to investigate whether individuals can be divided into metabotypes – different groups based on how individuals’ metabolism and intestinal flora respond to different diets, and whether these groups show different for individuals following an IBS diet plan or not.
“Finding objective biomarkers that can determine if an individual belongs to a certain metabotype for IBS symptoms could make life easier for many individuals with IBS. There are many indications that it is possible to use objective markers for more individually tailored dietary advice,” commented Professor Rikard Landberg, who leads the Division of Food and Nutrition Science at Chalmers University of Technology.
The new IBS study also clearly shows large individual variation when it comes to how different people are affected by a specific diet.
“Even if at group level we only see a moderate effect from fodmaps and no effect of gluten provocation, it may well still be the case that some individuals react strongly to these foods. That is why it is important to account for individual differences,” said Elise Nordin.