Abdominal bloating vs distension - causes and treatments

In case you missed it, we recently discussed abdominal bloating and distension in IBS, and discovered that although these terms are often used interchangeably, they are actually distinct. We learnt that whereas bloating is the subjective sensation of abdominal swelling (sometimes described as the feeling of an inflated balloon in the belly), abdominal distention refers to an actual increase in abdominal girth.

In this week’s blog post, we will explore causes and treatments for abdominal bloating and distension in IBS. 

What causes these symptoms?

People with IBS commonly believe that their symptoms of abdominal bloating and/or distension are caused by excessive gas production and/or accumulation. However, studies do not support these theories. Instead, factors such as impaired intestinal gas transit and visceral hypersensitivity are thought to play more important roles. 

Other less well established factors of possible importance include:

• mucosal immune activation, 
  
• altered bacterial flora, 
  
• sex hormones, and
  
• psychological factors. 

Understanding the relative importance of these different factors is important as it may help researchers to develop treatments that will more effectively reduce the severity of these symptoms in people with IBS. 

Treatment

Although bloating and distension are very common symptoms in IBS, they are considered challenging to treat in practice. This difficulty is in part due uncertainty regarding the underlying causes of bloating and distension, and a lack of robust efficacy data from treatment trials. While a very large number of studies have examined the efficacy of different IBS treatments, few of these consider bloating and/or distension as primary outcomes. This means that the studies were not always statistically powered to detect changes in these symptoms. There is also uncertainty about the most reliable way to measure changes in abdominal bloating and/or distension in treatment trials. 

Despite this uncertainty, treatments that have shown promise include:

• Low FODMAP diet  - A study that pooled results from several studies showed that people following a low FODMAP diet were 1.75 times more likely to experience a reduction in bloating than controls[1].
  
• Exercise[2, 3]
  
• Peppermint oil[4]
  
• Probiotics - These are live strains of bacteria that may benefit host health. Although studies have not consistently shown benefits in treating bloating, strains that have shown promise include  Bifantis 35624 and B. animalis [5]. 
  
• Gut directed hypnotherapy[6, 7]
  
• Prescription medications, such as 
  
• Pro-secretory agents (e.g. Linaclotide)
  
• Antibiotics (e.g.rifaximin) [5]  
  

The take home message? 

Bloating and distension are very common, but poorly understood symptoms in IBS. The terms bloating and distension are often (mistakenly) used interchangeably, although they are actually distinct. Differentiating between these symptoms is important as they may have different underlying causes, and treatment strategies may vary. If you suffer from symptoms of bloating and/or distension, work with your doctor to identify and trial therapies likely to improve your specific symptoms. 

References: 

1. Marsh, A., E.M. Eslick, and G.D. Eslick, Does a diet low in FODMAPs reduce symptoms associated with functional gastrointestinal disorders? A comprehensive systematic review and meta-analysis. Eur J Nutr, 2015.
   
2. Lacy, B.E., S.L. Gabbard, and M.D. Crowell, Pathophysiology, Evaluation, and Treatment of Bloating: Hope, Hype, or Hot Air? Gastroenterology & Hepatology, 2011. 7(11): p. 729-739.
   
3. Villoria, A., et al., Physical activity and intestinal gas clearance in patients with bloating. Am J Gastroenterol, 2006. 101(11): p. 2552-7.
   
4. Cash, B.D., M.S. Epstein, and S.M. Shah, A Novel Delivery System of Peppermint Oil Is an Effective Therapy for Irritable Bowel Syndrome Symptoms. Digestive Diseases and Sciences, 2016. 61: p. 560-571.
   
5. Schmulson, M. and L. Chang, Review article: the treatment of functional abdominal bloating and distension. Aliment Pharmacol Ther, 2011. 33(10): p. 1071-86.
   
6. V., M., et al., Hypnotherapy for irritable bowel syndrome: an audit of one thousand adult patients. Alimentary Pharmacology & Therapeutics, 2015. 41(9): p. 844-855.
   
7. Peters, S.L., et al., Randomised clinical trial: the efficacy of gut-directed hypnotherapy is similar to that of the low FODMAP diet for the treatment of irritable bowel syndrome. Aliment Pharmacol Ther, 2016. 44(5): p. 447-59.