The effect of diet on irritable bowel syndrome (IBS) varies from person to person. In some people, dietary factors may worsen symptoms.
Increased intestinal muscle reactivity and/or heightened sensitivity in IBS can cause the bowel to over-respond to stimuli. Even the normal digestive process, and not a particular food, may bring on or worsen symptoms at times.
Certain foods are known to stimulate gut reactions in general, and in those with IBS eating too much of these might worsen symptoms.
Cramping or Diarrhea Causing Foods
Meals that are too large or high in fat, coffee, caffeine, or alcohol may provoke symptoms of abdominal cramps and diarrhea.
Eating too much of some types of sugar that are poorly absorbed by the bowel can also cause cramping or diarrhea. Examples include:
- Sorbitol, commonly used as a sweetener in many dietetic foods, candies, and gums
- Fructose, also used as a sweetener and found naturally in honey as well as some fruits
Gas Producing Foods
Eating too much of foods that are gas producing may cause increased gaseousness. This is particularly the case since IBS can be associated with bloating and retention of gas. Gas producing foods may include:
A diet high in fiber can help some people with mainly constipation. Adding bulk to the diet, such as psyllium or methylcellulose preparation, may help regulate the bowel dysfunction. Psyllium, in particular, has been shown to be beneficial in relieving the constipation associated with IBS.
However, a diet excessively high in fiber may itself cause diarrhea and gas particularly in people with IBS.
Often, people with IBS report that some foods can be bothersome at certain times but not at other times. There is a sense of inconsistency and unpredictability.
It helps to realize that other factors related to symptoms may arise at the time of a meal. Maintaining a food and symptom diary for a minimum of one week can help identify triggering factors. [IFFGD has available a Personal Daily Diary to help sort this out.]
In some people, intolerance to a food product may be related to their symptoms. A sizeable proportion of people are unable to digest significant amounts of milk or milk products (lactose intolerance). They may experience symptoms similar to IBS when they eat or drink milk products.
Once this has been identified, the treatment is to avoid or reduce consumption of milk products in the diet. The use of artificial sources of the enzyme lactase may control the symptoms for some.
People may also experience worsening of their symptoms due to fructose intolerance. This occurs specifically with foods that contain fructose in excess of glucose.
Poorly absorbable, highly gas-forming carbohydrates are associated with increased IBS symptoms. These foods are collectively called FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols). This group of foods includes:
- fruits with fructose in excess of glucose (apples and pears)
- fructan-containing foods (onions, asparagus, artichokes, large amounts of wheat)
- raffinose containing foods (lentils, cabbage)
- sorbitol containing foods (plums, artificial sweeteners)
A FODMAPs diet in which these foods are avoided or reduced may provide some symptom relief in IBS.
For those with IBS who benefit from simple dietary modifications, it makes sense to adjust the diet.
It does not make sense to adopt unnecessarily limited diets. Physicians and patients need to talk about diet.
If dietary factors seem to influence symptoms, guidance needs to be provided by a knowledgeable health care professional (like a physician or registered dietitian) who can assess individual circumstances while helping make sure that nutritional needs are being met through a balanced diet and healthy eating habits.
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Source: Adapted from IFFGD Publication #101 revised and updated by Douglas A. Drossman, MD, Drossman Gastroenterology PLLC, Chapel Hill, NC.