Irritable Bowel Syndrome (IBS) Food Triggers

Irritable bowel syndrome (IBS) is a chronic digestive condition that is associated with cramping stomach pains, bloating of the stomach, and alternating diarrhea and constipation.

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Different people have different symptoms of IBS with varying severity. Even in the same person, symptoms wax and wane, lasting for a few days or months. Flare-ups often occur during periods of stress, or in response to specific trigger foods.

The prevalence of IBS is about 20%, overall. This condition is thought to affect up to one in five people at some point in their life, and it usually first develops when a person is between the age of 20 and 30. Additionally, IBS is twice as common in women as in men. Though it lasts a long time, significant remission may occur as time goes on.


IBS is due to some unknown pathology that causes the digestive tract mucosa to become hypersensitive to ordinary food. The resulting mucosal changes lead to indigestion and bacterial proliferation, with the production of several toxins that further aggravate the symptoms.

The pathophysiology of IBS includes the slowing of gut movements and an increase in mucosal permeability. Taken together, these aspects of the condition allow toxins to cross the mucosa, which subsequently alters the integrity of the gastrointestinal (GI) system. IBS also causes changes to arise in the gut flora, in addition to altering the interactions between the gut and the brain.

Food triggers are increasingly being identified, with 84% of patients finding that symptoms start or become worse after a meal.

Bloating due to bacterial fermentation of undigested food often produces pain for IBS patients. The delayed or rapid passage of food through the gut may also occur, depending on the exact processes that are occurring. Stress also plays a role in altering normal gut metabolism.

Food triggers

It has been observed that some foods may worsen the symptoms of IBS. These may include fatty foods that produce bloating, nausea, and pain.

Patients with IBS have a lower pain threshold in the intestine for normal stretching in response to food. Fat molecules may slow bowel transit, leading to the accumulation of gas which accounts for the symptoms.

IBS patients are primarily either constipated or diarrheal, and the same lipid meal can cause different reactions, of rectal pain and rectal urgency respectively.

Lactose-containing foods, for example, may precipitate IBS symptoms as a result of a possible lactase deficiency. The sugar then passes unabsorbed into the large bowel and is fermented to produce gas and short-chain fatty acids, which can further exacerbate the aforementioned symptoms.

Alcoholic or caffeinated beverages can also irritate the gut mucosa and, thus, worsen diarrhea. Artificial sweeteners in significant amounts, as well as foods like cabbage or beans that ferment readily in the body, can also worsen IBS symptoms.

How to identify food triggers

People with IBS can try to pinpoint which foods cause their symptoms by keeping a food diary. This will contain:

  • What foods are eaten at what time
  • What symptoms are experienced, and the time

After a few days, these entries can be discussed with the health care provider to help formulate a list of foods that should be avoided.

IBS dietary guidelines

People with IBS may consider going on a diet that greatly reduces or avoids foods such as starches and other carbohydrates that cannot be easily digested. This diet is also referred to as a low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) diet.

The term 'FODMAP' describes the types of sugars found in food products that are not quickly digested and absorbed. As a result, bacteria in the gut feed on them, leading to the release of gases that cause bloating and cramping.

Patients who are practicing a low FODMAP diet will avoid these food products for 1.5 to 2 months. After this period, these food products are carefully reintroduced one at a time to test how well they are being tolerated. During this period, developing a food plan is important to avoid deficiency diseases.

8 Foods to Avoid with IBS

Some foods that should not be eaten while practicing a low FODMAP diet include:

  • Fruits or fruit juice, including apples, apricots, mangos, watermelons, as well as canned fruit which contain a lot of natural fruit juice.
  • Vegetables such as artichokes, asparagus, broccoli, cabbage, cauliflower, garlic-containing spices, onions, mushrooms, lentils, and other legumes.
  • Milk and milk products.
  • Foods containing wheat and rye, which contain little absorbed, short-chain carbohydrates that are ideal for bacterial fermentation. These food products not only hold water but also produce gas, leading to stretching of the gut which is interpreted as pain because of the known hypersensitivity of the gut in these patients
  • Sweeteners such as honey or high-fructose corn syrup, as well as products containing sweeteners such as sorbitol, mannitol, or xylitol.


Further Reading

Last Updated: Sep 2, 2022

Dr. Liji Thomas

Written by

Dr. Liji Thomas

Dr. Liji Thomas is an OB-GYN, who graduated from the Government Medical College, University of Calicut, Kerala, in 2001. Liji practiced as a full-time consultant in obstetrics/gynecology in a private hospital for a few years following her graduation. She has counseled hundreds of patients facing issues from pregnancy-related problems and infertility, and has been in charge of over 2,000 deliveries, striving always to achieve a normal delivery rather than operative.


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