Specific diets less effective at preventing IBS, researchers say


“IBS is a very complex disease involving many factors, but our results indicate that the effects of specific diets are not as great as previously thought”

Many IBS sufferers avoid certain types of food and often exclude gluten. However, a recent study from Chalmers University of Technology and Uppsala University, Sweden, has not demonstrated a relationship between high intake of gluten and increased IBS symptoms. The researchers did find that a certain type of carbohydrate called “fodmaps” can aggravate intestinal problems, however, overall results indicate they also have less influence than previously thought.

“IBS is a very complex disease involving many factors, but our results indicate that the effects of specific diets are not as great as previously thought,” said Elise Nordin, PhD student in Food Science at Chalmers and lead author of the scientific article, published in the American Journal of Clinical Nutrition.

Irritable bowel syndrome affects around three to five percent of the world's population, and involves stomach pain, diarrhoea and constipation. In this study, which included 110 people with IBS, the researchers examined how people were affected by serving them rice puddings prepared in different ways. One was rich in gluten while the other contained large amounts of fodmap carbohydrates, which are fermentable carbohydrates, common in dairy products, types of bread and certain fruits and vegetables.

In addition to the specially prepared rice puddings, the researchers also served a neutral one that served as a placebo.

The participants in the double-blind study ate the puddings for one week per category.

The subjects' gastrointestinal systems were provoked through high doses (1.5 times daily intake in a normal population) of fodmaps or gluten. The fodmaps aggravated the symptoms, but not to the extent that the researchers had expected based on results from previous studies. Gluten, however, 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,” says Per Hellström, Professor of Gastroenterology at Uppsala University who held medical responsibility for the study.

Many IBS patients exclude gluten from their diet, despite the lack of scientific evidence. Results from previous research are inconsistent. Foods rich in gluten, such as bread, are often also rich in fodmaps – one theory has therefore been that it is the fodmaps in these foods, not the gluten, that causes the IBS symptoms. This shows the importance of studies for separating the effect of fodmaps and gluten.

The study is part of a project in which the researchers are looking for biomarkers in the intestinal flora or in the blood to be able to predict health outcomes. The researchers want to investigate whether individuals can be divided into metabotypes - groups based on how their metabolism and intestinal flora respond to different diets, and whether these groups show different IBS symptoms.

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“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,” says Professor Rikard Landberg, who leads the Division of Food and Nutrition Science at Chalmers University of Technology.