IBS and Food Avoidance
Irritable bowel syndrome (IBS) is a chronic, functional gastrointestinal (GI) disorder characterized by abdominal pain, bloating, constipation, and/or diarrhea. These symptoms can be persistent and greatly impact quality of life. There are three distinct subtypes: IBS-C, in which the person primarily experiences constipation; IBS-D, in which they primarily experience diarrhea; and IBS-M, which is a mixed type. IBS can also be diagnosed without a subtype.
For many people with IBS, certain foods can trigger or worsen symptoms, which is why treatments often focus on dietary changes. The low-FODMAP diet is one of the most common options, but each person can have different food triggers that might lead them to cutting out specific foods, either on their own or with the help of a dietitian or a physician. However, limiting foods in the long term can lead to nutritional deficiencies and can even make digestive symptoms worse. For example, some individuals find that fibrous foods such as vegetables and whole grains worsen symptoms, so they might cut these out and instead base their diet around white bread and meat. However, eating a diet low in fibre can negatively affect the function of the digestive tract and its microbiome, potentially worsening symptoms in the long term.
A study published in 20221 set out to compare patients with IBS who restricted or avoided food to those who didn’t to see whether they had different IBS experiences. They looked at 955 individuals with IBS, including 27% with IBS-C, 39% with IBS-D, and 34% with mixed or un-subtyped IBS. They ranged between 18 and 75 years of age and 75% were female. None of the subjects were following a specific diet and the researchers excluded anyone who had any severe physical or psychiatric disease, celiac disease, known food allergies, conditions or surgeries that could affect GI function, or any other disease that could explain symptoms.
The researchers found that 26% of respondents frequently did not eat when they were hungry, 54% frequently avoided foods, and 31% frequently found food unappealing, specifically because of their IBS. Individuals with all these behaviours made up 13% of the survey respondents, and the study authors defined this as the group with severe food avoidance and restriction. They experienced significantly lower quality of life and had more severe digestive, psychological, and physical symptoms than those without food restrictions. Individuals with IBS-D were more likely to report severe food avoidance and restriction, and it was especially prominent in those who reported a greater number of loose stools. Those with IBS-C were less likely to avoid and restrict food.
A subset of respondents completed in-depth food journals. The researchers compared the 20 individuals in this group who practiced severe food avoidance and restriction to the 226 who did not. Those in the restrictive group ate fewer calories on average (1,714 vs 2,102 kcal), less protein (65 vs 80 g), and fewer carbohydrates (168 vs 213 g). Especially concerning for GI health, they consumed less fibre (15 vs 19 g). They also had worrying low intakes of calcium, zinc, thiamin, and folate, with levels that were below the recommended daily intakes, making them at risk of developing deficiencies. Yet, body mass index was not lower in the restrictive group, but the researchers did not have information on whether these individuals had lost weight before the study period due to their dietary changes to manage IBS.
While dietary modifications can be a helpful tool in treating IBS, it is important to find the right balance between reducing symptoms and avoiding complications. If you are eliminating certain foods or food groups or are eating less than normal, it is a good idea to speak with your physician about testing for nutrient deficiencies. You can also work with a registered dietitian to find a meal plan that avoids these trigger foods but is nutritious and good for long term gut health.