Irritable bowel syndrome (IBS) is commonly used as an umbrella term to describe a wide range of clinical symptoms related to diarrhea, constipation, cramps, abdominal pain, gas, and bloating. There are strict criteria (Rome IV criteria) that are used to define IBS. However, IBS as a diagnosis is used much more loosely by a patient and even their doctors that involves a careful history and physical examination.
There are 3 different forms of IBS:
Diarrhea-predominant (D-IBS) involves abdominal discomfort or pain, urgency, and diarrhea.
Constipation-predominant (C-IBS) involves abdominal discomfort or pain, bloating, and constipation.
Alternating constipation and diarrhea (A-IBS) involve both.
The precise cause of IBS remains unknown. "Unknown" implies that it involves a variety of factors, such as infection, inflammation, medication, and stress, in a genetically predisposed individual.
Here's a great video by Monash University on how IBS affects the digestive system and some steps to help deal with symptoms.
IBS can be treated differently depending on the patients and a variety of other factors. There is no one medication that "cures" the disorder. Treatment focuses on improving symptoms and quality of life. However, modifying your diet can have a large effect on managing your symptoms.
Specific dietary IBS triggers are likely very common. The best initial management of IBS with dietary adjustment involves either a single-food elimination diet for some common triggers. These are lactose and fructose.
A common elimination diet (eg, low-FODMAP) is usually recommended. After starting a low-FODMAP diet you can aim for targeted reintroduction after 4 weeks, under the guidance of a registered dietitian.
FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols) are short-chain carbohydrates with limited (or minimal) small intestine absorption. This leads to hydrogen and methane production in the intestines, probable changes in gut flora, altering of colonic epithelial function, and may also cause local inflammation. These changes can significantly heighten gastrointestinal symptoms in patients with IBS, with excessive gas, bloating, and loose stools.
The Ideal FODMAP diet should include:
Small portions of nuts
Dairy (especially lactose-free milk)
Always talk to your doctor first.