FODMAPs are small sugar molecules that can be found in many common foods. These sugars are made up of carbon, hydrogen, and oxygen and provide energy for the body. However, for some people, FODMAPs may not be properly absorbed in the small intestine and can instead move to the large intestine (colon), where they are rapidly digested by gut bacteria and produce gas and other waste products. While it's estimated that a low FODMAP diet may help people with Irritable Bowel Syndrome (IBS), the scientific evidence is limited. People with IBS who try this diet may experience improvements in symptoms such as abdominal pain, bloating, gas, constipation, and diarrhoea.

What does FODMAP mean?

FODMAP is an acronym that stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, And Polyols.The following provides an explanation of each of these:

  • F- Fermentable: Fermentable carbohydrates are sugars that are broken down in the intestines by gut bacteria. The breakdown process produces gas and other by-products.
  • O- Oligosaccharides: Short chains of linked carbohydrates are known as oligosaccharides. A chain of fructose molecules called a fructan and a chain of galacto-oligosaccharides called a galacto-oligosaccharide are two oligosaccharides that humans cannot properly digest and absorb in the small intestine.
  • D- Disaccharides are a type of carbohydrate that are made up of two linked molecules. The sugar lactose, which can be found in milk and dairy products, is a disaccharide made up of glucose and galactose. Before being absorbed in the small intestine, lactose needs to be broken down by the digestive enzyme lactase. In people with lactose intolerance, the amount of lactase enzyme is insufficient to properly digest lactose, and lactose instead travels to the colon where fermentation takes place.
  • M- Monosaccharides are single molecules of a carbohydrate. The sugar called fructose, which is present in many fruits and some vegetables, is a monosaccharide, which means that it does not need to be digested in order to be absorbed. When foods with an equal amount of fructose and glucose are consumed, the glucose aids in the full absorption of the fructose. However, fructose absorption is reliant on the activity of sugar transporters found in the intestinal wall when fructose concentrations are higher than glucose concentrations. Individuals have different capacities for absorbing excess fructose. Since the capacity of sugar transporters is reduced in individuals with fructose malabsorption, extra fructose is transported to the colon, where fermentation takes place.
  • A- And
  • P- Polyols: In the small intestine, humans can only partially digest and absorb polyols, also known as sugar alcohols. Polyols like sorbitol, mannitol, xylitol, maltitol, and isomalt imitate the sweetness of sucrose (table sugar), but because their absorption is much slower, only a small amount of what is consumed is actually absorbed. In sugar-free and diet goods, polyols are frequently used as low-calorie sweeteners.

How do FODMAPs impact individuals with digestive disorders?

FODMAPs may not be the root cause of digestive disorders such as Irritable Bowel Syndrome (IBS), but they can still evoke gastrointestinal symptoms. Upon reaching the colon, FODMAPs attract fluid and undergo fermentation by gut bacteria, producing hydrogen and methane gases. This results in the intestine being stretched and activating the nerves surrounding the digestive organs. For some people with IBS, the nerves of their gut are highly sensitive, causing an overreaction to even the slightest change in intestinal volume, resulting in IBS symptoms.

What are the food sources of FODMAPs?

FODMAPs are present in many common foods such as fruits, vegetables, beans, dairy products, and sweeteners. Each person has a unique level of tolerance for FODMAPs and some foods may cause more issues than others. By reducing the intake of high-FODMAP foods and controlling the overall FODMAP load during each meal, it is possible to alleviate gastrointestinal symptoms for some people with digestive disorders.

Dr. Manik Sharma
Department of Gastroenterology
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