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News release on diet for IBS claims “major improvement”; but what exactly does that mean?

Clinical Trial Demonstrates Success of Low FODMAP Diet

Our Review Summary

nutritionistThis news release touts results from a single-blind randomized controlled trial of a diet that’s emerged in the last decade to relieve symptoms of irritable bowel syndrome (IBS), a tough-to-treat gut disorder with no cure. The low FODMAP (an acronym for Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols) diet eliminates foods that contain large amounts of short-chain carbohydrates that are poorly absorbed in the small intestine. In IBS patients those carbohydrates are believed to feed bacteria in the colon, generating gases that lead to bloating, abdominal discomfort, and changes in bowel function.

The low-FODMAP diet restricts an array of foods including honey, high fructose corn syrup, high-fructose fruits such as apples, dairy, wheat, garlic, onion, legumes and beans, some artificial sweeteners, and stone fruits such as avocado and peaches. In the University of Michigan study, registered dietitians educated and monitored 83 patients assigned to either a low FODMAP diet or a healthy control diet in which FODMAPs were not excluded. The trial concluded that after four weeks, the low FODMAP diet improved quality of life, ability to perform activities, and sleep quality compared to the control diet. While the news release rightly encourages patients to consider dietary changes that could improve their symptoms, it would have been more helpful to readers if it included some cautions about the study’s limitations, potential cost of working with an advising dietitian, and the drawbacks of following such a restrictive diet.


Why This Matters

IBS is a chronic illness that affects an estimated 5 to 15 percent of the developed world but historically has been understudied and undertreated. Symptoms can have a profound effect on sleep, personal relationships, travel, diet, and sexual function, and impose both direct medical costs and indirect costs such as absenteeism from work and school along with decreased quality of life, according to a report in the Journal of Managed Care Pharmacy. The report set the annual cost of IBS treatment in the U.S. at between $1.7 billion and $10 billion in direct medical costs (excluding prescription and over-the-counter drug costs) and $20 billion for indirect costs.

There’s no diagnostic test for IBS, and in the past patients were often told their symptoms were the result of a mental disorder. The last decade has seen a surge in efforts to develop effective treatments, but new drugs have met with limited success and tend to be expensive. The low FODMAP diet was originally developed by a research team at Monash University in Melbourne, Australia, where researchers measured the FODMAP content of foods, creating a database and smartphone apps to help patients track intake. Studies have shown that a low FODMAP diet improves symptoms for a majority of IBS patients, but the diet is demanding because it rules out many common foods. It’s often used as a temporary elimination plan; after several weeks, when symptoms disappear, foods are reintroduced slowly over the course of months to help patients determine which specific foods trigger their symptoms. Rigorous study findings that support the efficacy of the low FODMAP diet in the U.S. could prompt more clinicians and patients to embrace it.


Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

A low FODMAP diet might raise grocery bills, since it requires specialty products that eliminate wheat, lactose, fructose, and other common ingredients. It’s understandable that the news release doesn’t address a potential modest increase in food expenses. However, the cost of working with a registered dietitian over several months to adopt a low FODMAP diet and tailor it to a patient’s individual food tolerances is significant. That should have been addressed in the news release, along with how that cost might be offset by eliminating less effective pharmaceutical therapies and increasing the productivity of patients who regularly miss work because they are debilitated by IBS symptoms.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The news release reports some numbers. It says more than half of the patients on the low FODMAP diet experienced “major improvement” of their abdominal pain compared with 20 percent of the control group, and 61 percent of low FODMAP patients had a “meaningful improvement” in quality of life versus 27 percent for the control group. However, it should have described for readers what these improvements mean from a clinical standpoint. Is the researchers’ definition of “major improvement” the same as what patients expect when they hear that term? Offering some specifics would have helped clarify.

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

While a dietary intervention may seem relatively harmless, there are notable risks. Potential nutritional deficiencies and changes in gut bacteria following a low FODMAP diet long-term have not been studied. Some people may also find it  inconvenient to be on a restricted diet that prohibits consuming their favorite foods.

Does the news release seem to grasp the quality of the evidence?

Not Satisfactory

The release skips over some important details. First, diet studies are notoriously unreliable. The news release does not specify how researchers determined whether patients were actually following their assigned diets. Did they keep logs? Did they report their specific consumption to researchers? Did patients assigned to the control group avoid some FODMAPs anyway because they knew those foods might aggravate their symptoms? What accounted for symptom improvements of patients in the control group? And why might the low FODMAP diet have failed to work for all patients? The news release could have done a better job exploring these questions.

Second, the news release does not explain the criteria for selecting patients to study, and how that might have affected the results. For example, if the selected patients had demonstrated an ability to adhere to treatment regimens, that should be considered when determining whether similar results could be achieved in a general population of patients. Further, the news release should have explained why nine of the 92 patients deemed eligible for the study did not complete the study period. Did some patients find the low FODMAP diet or the control diet too difficult to follow?

Third, the news release should have mentioned that all patients in the study had one type of IBS, IBS with diarrhea. Two other types, IBS with constipation and IBS with mixed constipation and diarrhea, were not included.

In general, we think the news release could have done a better job of underscoring the difficulty of following a low FODMAP diet and how that could undermine its efficacy, as well as explaining the diet’s role as a framework for eliminating symptoms before reintroducing foods one by one to test a patient’s tolerances. The release waits until the very end to address these thorny issues, including the need for patients to seek help from a dietitian and the need for researchers to determine why foods can trigger different reactions in different patients.

Does the news release commit disease-mongering?


There’s no evidence of disease mongering.

Does the news release identify funding sources & disclose conflicts of interest?


The release says the research was funded by the University of Michigan Nutritional and Obesity Center and Prometheus Laboratories Inc. It might have disclosed that Prometheus Laboratories is owned by the global food and beverage giant Nestlé, and that it sells diagnostic tests for IBS.

Does the news release compare the new approach with existing alternatives?


The news release mentions “medications that are often expensive, usually ineffective and frequently cause unwelcome side effects.” Some elaboration would have been useful.

The majority of IBS patients actually do get relief from standard dietary changes and occasionally medications (depending on whether they have diarrhea or constipation predominant). This was a little misleading as the news release suggests that other methods aren’t effective.

Does the news release establish the availability of the treatment/test/product/procedure?


Information about the low FODMAP diet is widely available online.

Does the news release establish the true novelty of the approach?


The news release states that the low FODMAP diet isn’t new. But it also states that the study is the “first of its kind,” “the largest of its kind,” and that this is the first time the FODMAP diet has been studied in the United States.

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?


The news release hypes the study’s importance as the “first of its kind study in the U.S.” and quotes a researcher saying it’s the “only methodically rigorous clinical trial” to show that dietary changes can improve not only symptoms but also quality of life for patients with IBS.” These phrases might overstate the study’s significance somewhat, since there’s ample evidence supporting the efficacy of a low FODMAP diet for some IBS patients. But overall, the language is justifiable.

Total Score: 6 of 10 Satisfactory


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