+AA
Fr
Back
Evidence Summary

What is an Evidence Summary?

Key messages from scientific research that's ready to be acted on

Got It, Hide this
  • Rating:

In people with irritable bowel syndrome, very-low-quality evidence suggests low FODMAP diets improve symptoms. There isn’t enough evidence to draw conclusions about gluten-free diets.

Dionne J, Ford AC, Yuan Y, et al. A Systematic Review and Meta-Analysis Evaluating the Efficacy of a Gluten-Free Diet and a Low FODMAPs Diet in Treating Symptoms of Irritable Bowel Syndrome. Am J Gastroenterol. 2018 Jul 26. [Epub ahead of print].

Review question

In people with irritable bowel syndrome (IBS), do diets without gluten or low on fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAPs) improve symptoms?

Background

IBS is a common disorder. It affects the large intestine, but does not harm it. We don’t have a specific test to diagnose IBS, and we don’t know exactly what causes it. People with IBS have symptoms such as constipation, diarrhea, stomach pain or cramps, bloating, and gas. IBS symptoms may be treated with drugs, changes in diet, probiotics, or stress-management strategies. This review looks at whether changing your diet can improve IBS symptoms.

A low FODMAP diet means that you remove specific foods from your diet that are poorly absorbed in the bowel (e.g., garlic, onions, many types of beans–a full list is easily found on the Internet). A gluten-free diet means that you remove foods that contain a protein found in wheat (e.g., cereals, pasta, breads).

How the review was done

The researchers did a systematic review of studies available up to November 2017. They found 9 randomized controlled trials that included 508 people.

The key features of the studies were:

  • people were at least 18 years of age and were diagnosed with IBS;
  • 2 trials evaluated gluten-free diets (GFDs), and 7 evaluated low FODMAP diets;
  • GFD and low FODMAP diets were compared with placebo, usual diets, diets including gluten, or higher FODMAP diets; and
  • people used the diet for 3 to 9 weeks.

What the researchers found

  • Compared with diets including gluten, GFDs improved IBS symptoms at 6 weeks in 1 trial of 72 people but did not improve symptoms at 6 weeks in another trial of 39 people.
  • Low FODMAP diets improved IBS symptoms overall at 3 to 9 weeks compared with other diets, high FODMAP diets, or placebo.

The quality of the evidence was considered to be very low, which means that new studies might show different results.

Conclusions

In people with irritable bowel syndrome, there is very-low-quality evidence that low FODMAP diets improve symptoms. We don’t have enough evidence about gluten-free diets to draw any conclusions.

Gluten-free diet (GFD) or low FODMAP diet vs control diet* for irritable bowel syndrome (IBS)

Type of diet

Number of trials (number of people)

IBS symptoms with GFD or low FODMAP diet†

IBS symptoms with control diet

Absolute effect of GFD or low FODMAP diet

GFD

1 trial (39 people)

53%

70%

No difference in effect‡

 

1 trial (72 people)

16%

74%

Symptoms continued in about 58 fewer people out of 100 (from as few as 39 to as many as 77)

Low FODMAP diet

7 trials (397 people)

43%

62%

Symptoms continued in about 19 fewer people out of 100 (from as few as 7 to as many as 28)

FODMAP = fermentable oligosaccharides, disaccharides, monosaccharides, and polyols.

*Placebo, usual diets, diets including gluten, or higher FODMAP diets.

†The proportion of patients with continuing symptoms in the GFD and low FODMAP diet groups were weighted. This means it may be a little different than you would expect if you just divided the number of people who had ongoing symptoms with the number of people who used the diet.

‡Although the rates for the 2 groups look a little different, the differences were not statistically significant. This means that the differences could simply be due to chance rather than due to different diets.



Related Topics


Glossary

Placebo
A harmless, inactive, and simulated treatment.
Randomized controlled trials
Studies where people are assigned to one of the treatments purely by chance.
Systematic review
A comprehensive evaluation of the available research evidence on a particular topic.

Related Web Resources

  • Ulcerative colitis: Should I have surgery?

    OHRI
    This patient decision aid helps people who have ulcerative colitis and are considering surgery to remove the colon to decide on whether to have surgery or to keep taking medicine by comparing the benefits, risks and side effects of both options.
  • Heartburn: treatment options.

    OHRI
    This patient decision aid helps people looking to treat heartburn decide on treatment options. It facilitates the process by outlining and comparing the two treatment options: proton pump inhibitor (PPI) medication and laparoscopic surgery.
  • Irritable Bowel Syndrome

    Patient.co.uk
    Irritable Bowel Syndrome (IBS) is a common problem that can cause bloating, pain, and changes in stools. Eat more soluble fiber and drink water to help relieve symptoms. Also try exercise and stress management. More details and a video in this resource.
DISCLAIMER These summaries are provided for informational purposes only. They are not a substitute for advice from your own health care professional. The summaries may be reproduced for not-for-profit educational purposes only. Any other uses must be approved by the McMaster Optimal Aging Portal (info@mcmasteroptimalaging.org).

Register for free access to all Professional content

Register
Want the latest in aging research? Sign up for our email alerts.
Subscribe
© 2012 - 2017 McMaster University | 1280 Main Street West | Hamilton, Ontario L8S4L8 | +1 905-525-9140 | Terms Of Use