A 12-week low FODMAP diet not only eased pain, bloating, and diarrhea in IBS patients but also raised levels of the gut hormone GLP-1. However, the hormone shift didn’t fully explain the symptom relief.
Study: Increase in circulating GLP-1 following low FODMAP diet in irritable bowel syndrome patients. Image credit: PeopleImages.com - Yuri A/Shutterstock.com
A diet that restricts the intake of fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) has been used to improve gut health. A new study published in Frontiers in Nutrition highlights the utility of this diet in managing symptoms of irritable bowel syndrome.
Background
Irritable bowel syndrome (IBS) is a common multifactorial gastrointestinal condition that significantly reduces the overall quality of life. Depending on the predominant symptoms, there are four types of IBS: IBS-diarrhea, IBS-constipation, IBS-mixed, and IBS-unspecified.
The intestinal hormone glucagon-like peptide 1 (GLP-1) is potentially associated with IBS pathophysiology. This hormone is secreted from the intestine in response to ingested food and stimulates insulin release from the pancreas to reduce blood glucose levels. It also helps reduce appetite, slow down gastric emptying, and induce weight loss.
The dietary intake of fermentable carbohydrates, including oligosaccharides, disaccharides, monosaccharides, and polyols, has been found to exacerbate IBS symptoms, and so a low FODMAP diet has been found to improve IBS symptoms.
Given the potential implications of both GLP-1 level and FODMAP intake in IBS, researchers at the Haukeland University Hospital, Norway, investigated the impact of a low FODMAP diet on circulating GLP-1 levels in patients with IBS-diarrhea and IBS-mixed.
Study design
The study included 30 adult patients with moderate to severe diarrhea or mixed-type IBS. They followed a strict low-FODMAP diet for 12 weeks, guided by a registered dietitian, with monthly follow-ups to assess compliance and safety.
All participants were evaluated for IBS symptom severity, circulating GLP-1 levels, total FODMAP intake, and body weight before and after the 12-week dietary intervention. This was a single-arm, pre-post interventional study without a control group for comparison.
Key findings
The study found a significant reduction in total FODMAP intake after completing the 12-week dietary intervention, indicating good adherence to the low FODMAP diet. Dietary records were complete for 15 participants at both baseline and week 12, with additional week 4 records supporting overall adherence.
Following a 12-week low FODMAP diet intake, the participants exhibited a significant induction in circulating GLP-1 levels (increasing modestly from about 3.3 pM to 3.6 pM), significantly reduced body weight, and significantly improved IBS and gastrointestinal symptoms. Improvements were seen in pain, bloating, and diarrhea, while constipation and satiety symptoms did not change significantly.
The study could not find any correlation between changes in GLP-1 levels and changes in body weight, IBS, or gastrointestinal symptoms.
Study significance
The study highlights the benefits of a low-FODMAP diet in managing diarrhea and mixed-type IBS. According to the study findings, consuming a low-FODMAP diet for 12 weeks can increase blood levels of GLP-1 and improve IBS symptoms.
Existing evidence indicates that circulating GLP-1 levels are positively associated with body mass index (a measure of overweight or obesity) and that weight loss reduces circulating levels of GLP-1. However, the current study could not find any association between circulating GLP-1 and body weight changes, indicating that low FODMAP diet-mediated changes in GLP-1 levels are not solely due to changes in body weight.
Similarly, the study could not find any association between changes in circulating GLP-1 and changes in IBS symptom severity, highlighting the need for identifying underlying mechanisms driving these changes.
The observed changes in GLP-1 level following low FODMAP diet intake might be explained by chemosensory mechanisms in enteroendocrine cells involved in food intake-mediated changes in intestinal hormone levels. A low FODMAP diet may alter the exposure of enteroendocrine cells to gut microbial metabolites, leading to altered production of GLP-1.
Gut motility and intestinal barrier integrity are two major components of IBS, which are affected by both FODMAPs and GLP-1. Therefore, an in-depth understanding of the association between GLP-1 and a low-FODMAP diet has important therapeutic implications.
Both GLP-1 analogs and the low FODMAP diet have shown promising therapeutic outcomes in patients with IBS. Existing evidence indicates that GLP-1 analogs help reduce pain and control gut motility in IBS patients. Similarly, a low FODMAP diet has been found to affect gut motility and visceral hypersensitivity, which are essential aspects of the brain-gut axis in IBS.
This single-center study involved only IBS patients; no healthy control group was included. Therefore, the study could not demonstrate whether GLP-1 levels are different between IBS patients and healthy controls. Further studies are needed to compare circulating GLP-1 levels in different IBS subgroups and healthy controls. Such studies could provide a more in-depth understanding of the pathophysiological basis of the change in GLP-1 levels in IBS.
Furthermore, this small-scale study assessed only a single dietary intervention and found a significant increase in circulating GLP-1 levels. These findings provide a foundation for future studies to investigate the impact of other dietary interventions on enteroendocrine hormones.
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