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What are FODMAPs?

Researchers at Monash University in Australia coined the FODMAP acronym to classify groups of carbohydrates (sugars and fibers) found in foods and beverages, that are similar in length and structure. These, "short-chain" carbohydrates have been shown to be poorly absorbed in individuals living with digestive sensitivities, including Irritable Bowel Syndrome (IBS), and resulting in a common set of gastrointestinal symptoms including abdominal pain, bloating and gas, constipation and/or diarrhea.

FODMAP stands for the following:

  • F Fermentable – Quickly broken down by bacteria in the gut and produce gas
  • O Oligosaccharides (Fructo-and galacto-oligosaccharides) – Found in select vegetables, legumes, fruits, grains, nuts and teas
  • D Disaccharides (Lactose) – Found in select milk and milk products
  • M Monosaccharides (Fructose) – Found in select fruits, vegetables and sweeteners
  • A And
  • P Polyols (Sugar Alcohols) – Found in select fruits, vegetables and artificial sweeteners

A few more things to know:

  • Fructooligosaccharides (FOS, fructans) are a chain of 3–9 fructose molecules with a glucose molecule at the end
  • Galactooligosaccharides (GOS, galactans) are a chain of 3–9 galactose molecules with a fructose molecule at the end
  • Disaccharides, specifically lactose (a natural milk sugar), is made up of 2 sugar molecules (glucose and galactose)
  • Monosaccharides, specifically fructose, is made up of a single sugar molecule where excessive amounts can be difficult to absorb

Polyols are known as sugar alcohols including sorbitol, mannitol, xylitol and maltitol.

FODMAPs in the Body

For people living with digestive sensitivities, including those with Irritable Bowel Syndrome (IBS), foods high in FODMAPs are not the cause of the problem, rather they can trigger gastrointestinal symptoms causing digestive discomfort and anxiety.

Poor Absorption of FODMAPs Leads to Distention, Pain, and Discomfort

Research into FODMAP-containing foods has identified that foods high in FODMAPs have the following common effects for many people with IBS:

  1. FODMAPs can be poorly absorbed in the small intestine.
  2. FODMAPs can cause excessive water to be drawn into the intestines.
  3. FODMAPs can become rapidly fermented by bacterial present in the colon, which produces gas.
  4. Water and gas build up creates distention, cramps and diarrhea or constipation.

Why are they Poorly Absorbed?

  • FOS, GOS - Humans do not have the enzymes to break these down, so they cannot be absorbed in the small intestine. This leads to rapid fermentation in the large intestine by the microbiota, causing gas formation.
  • Disaccharides – Many IBS sufferers lack the enzyme lactase needed to break lactose down lactose to its monosaccharide constituents (glucose and galactose).
  • Monosaccharides – Fructose is easily absorbed, but it can be malabsorbed in excess of glucose.
  • Polyols – Sugar alcohols are slowly and incompletely absorbed by humans, sometimes even marketed as a laxative or requiring of this possible effect upon consumption.

Are there Clinical Tests to Help Identify FODMAP Malabsorption?

  • Clinical tests to determine FODMAP malabsorption are not commonly used since the elimination of the foods with resolved symptoms may be adequate to demonstrate intolerance.
  • Some gastroenterologists may use breath hydrogen tests. Following consumption of a test sugar (e.g., fructose, lactose and sorbitol), hydrogen levels in the breath are measured. A significant rise in breath hydrogen indicates fermentation by bacteria (also called the gut microflora or microbiota) in the large intestine.
  • Note fructans and galactans are always malabsorbed and fermented as we do not break them down, so they are not tested.
  • Polyol tolerance is generally tested through dietary elimination and FODMAP re-challenge.

FODMAPS vs. Gluten

Is Gluten a FODMAP?

No. Gluten is not a FODMAP. Gluten is a protein that people with Celiac disease cannot digest. FODMAPs are short-chain carbohydrates. The two overlap because wheat, rye and barley contain gluten and oligosaccharides (fructans).

While gluten-free products may seem like a good idea on a Low FODMAP Diet, many gluten-free items may contain higher FODMAP ingredients. Read the labels in all food products.

Gluten Intolerance: Celiac Disease and Non-Celiac Gluten Sensitivity

Celiac Disease

For the person with Celiac Disease, consumption of gluten results in an easily diagnosable immune reaction with inflammation and damage occurring in the small bowel.

Non-Celiac Gluten Sensitivity (NCGS)

A patient that does not have Celiac Disease or food allergies may still have GI symptoms following the consumption of gluten. Although people with NCGS are often put on a gluten-free diet, this does not always effectively eliminate symptoms of gas and bloating. In fact, some people who believe they are gluten-sensitive may in fact be FODMAP-sensitive. A Low FODMAP Diet could be an alternative nutrition solution for these individuals with the goal to help reduce their symptoms associated with digestive discomfort and improve their quality of life.

FODMAPS vs. Lactose

Dairy refers to any milk or products made with milk that comes from animals. People avoiding dairy would eliminate all foods and beverages made from milk and milk derivatives, including casein and whey proteins, which are often used in non-dairy foods. Lactose is a type of sugar found in milk products. People who are unable to properly digest lactose, may be able to use lactase enzymes to help breakdown these sugars, and continue to eat the dairy foods they enjoy. They may also choose to use lactose-free dairy products, which are widely available. A lactose-free diet is not sufficient for someone interested in eliminating all dairy. A dairy-free diet is overly restrictive for someone needing only to eliminate lactose.

What Are FODMAPs?