Low FODMAP diet: a new therapy for IBS

Suffering from chronic gas, bloating, diarrhea or constipation, people with IBS will try just about anything to feel better.  Many undergo elimination diets in attempt to ascertain which foods are causing symptoms, with common allergens (dairy, wheat, soy) as popular suspects. While needle-in-a-haystack elimination diets may help, there is a new, evidence-based diet protocol that better identifies IBS trigger foods and improves symptom control in three out of four people with IBS.  It is called the Low FODMAP diet.

What are FODMAPs?

FODMAP stands for Fermentable Oligo-saccharides, Di-saccharides, Mono-saccharides and Polyols (saccharide means sugar).  Unlike the long chains of sugar found in starchy potatoes and rice, FODMAPs are small in size.  These sugars, when poorly absorbed, draw water into the intestines through osmosis, resulting in diarrhea.  The unabsorbed sugars also feed colonic bacteria resulting in gas and bloating.  Think of FODMAPs as “fast food for the gut."

While FODMAP malabsorption and subsequent fermentation occurs in most people, individuals with IBS or other Functional Gastrointestinal Disorders (FGID) may have hypersensitivity to gas production.  Additionally, FODMAPs have a cumulative effect and each IBS sufferer has a difference tolerance level for each type of sugar – just because a food contains FODMAPs doesn’t mean it cannot be consumed in any amount.

According to FODMAP expert, Kate Scarlata, the Low FODMAP diet is an opportunity to investigate tolerance and manage symptoms.  The general idea is to remove all FODMAP-containing foods from the diet in a wash out period lasting 2 to 6 weeks.  Once symptoms are greatly improved, FODMAPs can be gently reintroduced to the diet, one at a time, in varying amounts, to determine what is tolerated.  In other words (and I really want to stress this), the FODMAP-free diet is a learning diet, not a long-term elimination diet.  Many of the foods that contain FODMAPs are healthy, delicious foods and should be added back to the diet as soon as tolerable amounts are identified.  Let’s meet the FODMAPs now.

In which foods are FODMAPs found?

  • Mono-saccharides are single units of sugar (“mono” means one) like glucose, fructose and galactose.  Most are readily absorbed from the intestinal lumen into the blood stream, except for fructose in excess of glucose, which is found in honey, some high fructose corn syrups, and certain fruits like apples, cherries, peaches and pears.
  • Di-saccharides are made up of two sugars stuck together (“di” means two). While most humans are able to breakdown the disaccharides sucrose and maltose, some individuals are unable to digest lactose, the sugar naturally found in milk and milk products.  Indeed, scientists have known about lactose intolerance, and the subsequent gas and diarrhea associated with it, for years. 
  • Oligo-saccharides, or oligos for short, are short chains of sugar typically 3-10 units long (“oligo” means few or scanty).  This includes fructans, fructo-oligosaccharides (FOS) and galacto-oligosaccharides (GOS).  Oligos are found in foods like wheat, rye, onions, garlic, and legumes such as beans and lentils.
  • Polyols stands for sugar alcohols such as sorbitol and mannitol.  Polyols are found in some fruits and vegetables and often added to processed foods as artificial sweeteners.

Where did the Low FODMAP diet originate?

The Low FODMAP diet was developed by researchers at Monash University in Melbourne, Australia.  While evidence that food triggers gastrointestinal symptoms had been around for many years (e.g. lactose intolerance, beans are gassy foods), advances in science and technology allowed these researchers to look at the evidence in a new, innovative way.  The team at Monash University combined gave “structure” to the knowledge and provided the first evidence that the Low FODMAP diet improves IBS symptoms.  They also created a fantastic app, which I highly recommend.  

The FODMAP App (by Monash University)

The app provides accurate information about foods that trigger IBS reactions in order to help IBS sufferers manage their symptoms.  My favorite part of the app is the food guide which uses a stoplight system to identify FODMAP foods: red means avoid, orange means caution, green is safe.

  • Red indicates that a food is high in FODMAPs and should be avoided.  
  • Orange means the food is moderate in FODMAP and may be tolerated by some.  
  • Green indicates the food is low in FODMAPs and safe for consumption.

One fact that surprises most folks is that the level of ripeness can determine whether or not a food is safe.  For example, a green banana is low in FODMAP but, as the banana ripens, the starches turn into sugar making a ripe banana high in FODMAP and, thus, a "red light" food.  Check out the short video below for more information about the app.

The diagnosis of IBS should be made by a medical practitioner.  If you’ve read this far, it is likely you’ve already been diagnosed.  However, it is highly recommended that you employ the help of a medical professional before starting a Low FODMAP diet.  Your primary care physician can order tests to help you personalize the FODMAP diet by determining which FODMAPs are OK for you to consume.  Before making an appointment, you may want to familiarize yourself with these tests as not all health professionals are aware of these diagnostic options.

The FODMAP Breath Test

The FODMAP breath test identifies malabsorption of fructose, lactose, and sorbitol.  Each sugar is tested individually.  After swallowing a measured amount of sugar, the test measures the amount of gas in the breath.  If the sugars are poorly absorbed, the intestinal bacteria ferment the sugar to produce gases such as hydrogen and methane.  These gases are absorbed across the intestine, carried through the bloodstream to the lungs, and exhaled.  If your breath test for fructose, lactose and sorbitol are all negative, then you would only need to restrict the other FODMPs from your diet: fructans, GOS, and mannitol.  In addition to sugar malabsportion, the breath test also confirms proximal small intestinal bacterial overgrowth (SIBO).  Getting a breath test done prior to starting a low FODMAP diet and help reduce the number of foods you need to avoid.  Learn more about breath test here.

Again, I want to stress that that FODMAP diet is not a life-long diet.  There are many healthful foods that are excluded on a Low FODMAP diet.  The purpose of doing a Low FODMAP diet is to determine which FODMAPs you are most sensitive to and in which amounts so that you can ultimately incorporatate as many foods as possible in quantities that you tolerate.  The end goal is for each IBS sufferer to be satisfied with symptom management while eating the most healthy, varied diet possible.