Specific diets are less important for IBS

Dec 22, 2021

Many IBS sufferers avoid certain diets and often exclude gluten. However, a large new study from Chalmers University of Technology and Uppsala University, Sweden, does not show 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, the overall results indicate that they also have less influence than previously thought.

IBS (irritable bowel syndrome) affects around three to five percent of the world’s population, and involves symptoms such as stomach pain, diarrhea and constipation. In the new study, which included 110 people with IBS, the researchers examined how people were affected by serving them rice puddings prepared in different ways. One variety was rich in gluten while the other contained large amounts of carbohydrate of the ‘fodmap’ variety — that is, fermentable carbohydrates, including certain chains of fructose and lactose. Many foods are rich in fodmaps, including 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.

Double-blind knowledge of the rice puddings

The participants in the study ate rice puddings rich in fodmaps, gluten and the placebo in random order, for one week per category. The study was double-blind, meaning neither the participants nor the researchers knew who ate which rice pudding and when.

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.

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 few participants and have not been conducted double-blind, which makes it difficult to objectively evaluate the results.

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.

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 be able to predict health outcomes. The researchers want 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 IBS symptoms.

The new IBS study also clearly shows large individual variation when it comes to how different people are affected by a specific diet.

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