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FODMAPs Breakdown

So, What's the Deal?

FODMAP refers to Fermentable Oligosaccharides, Disaccharides, Monosaccharides, And Polyols. Foods that contain FODMAPs are generally not absorbed in the small intestine and move into the large intestine to promote the growth of healthy bacteria. Because they are not absorbed in the small intestine, they can cause IBS or symptoms of IBS in some individuals. Symptoms of IBS include bloating, gas, fatigue, brain fog, difficulty sleeping, abdominal pain, and general food intolerance.

Working from the largest to smallest molecule:

  • Oligosaccharides are many monosaccharides joined together. Examples of oligosaccharides include garlic, legumes, wheat, asparagus, and many other plants.

  • Disaccharides are formed when two monosaccharides join together. Lactose is a disaccharide and found in milk along with sucrose which is found in table salt.

  • Monosaccharides are the most basic form of sugar and are considered a simple sugar. Simple meaning they cannot be broken down (hydrolyzed) any further. Glucose is an example of a monosaccharide and found in whole grains, pasta, and some veggies.

Polyols are sugar alcohols used as a sweetener in many foods but with lower calorie content. Examples of polyols include sorbitol and xylitol. Mannitol is a common polyol found in foods such as mushrooms, cauliflower, apples, and pears (Barrett, J. S., 2017).

Purpose and Concepts of FODMAPs Diet

The idea behind the FODMAPs diet is to lower your intake of foods that fall within the FODMAPs group to improve IBS (irritable bowel syndrome). According to the University of Michigan, utilizing the FODMAPs diet strategy correctly works to reduce and can even completely eliminate IBS symptoms in 50-75% of individuals (DuBois, 2020).

Formisano, L. (n.d.). 

If attempting to follow the FODMAPs strategy, generally a person should restrict all at once the list of high FODMAP foods. However, the list of foods to avoid can be quite large and overwhelming to someone trying to improve on any or all of these symptoms. A smaller step that can lower stress from reducing so much from one's normal diet is to start with one section of the FODMAPs diet to restrict/lower intake and see if there is any change in symptoms. If the symptoms stay the same then the food you restricted most likely isn’t what is causing the issues, thus, moving onto the next group to start to rule out what is causing you trouble. It is advised that when following the FODMAP diet, the restrictive phase should last approximately 2-6 weeks (Tuck, C., & Barrett, J., 2017). This is completely dependent on the person, their symptoms, and finding a basis of adherence that works well for them. If available, working with an experienced dietitian is advised to find the best solution to maneuver FODMAPS and IBS or any alike symptoms.

A person may experience that many of the food items on the list to avoid/lower were the issue for them, and by taking those foods out of their diet for a period of time and slowly reintroducing them in small amounts can improve the negative effects they create on the gut. The reintroduction phase or “challenging phase” length depends on the person and the severity of their symptoms. The purpose of this phase is to slowly reintroduce the restricted foods and see if they are well-tolerated, moderately tolerated (mild symptoms), or not tolerated at all (complete food avoidance). Once these foods are identified and their symptom level is understood, a person can begin to organize and execute a version of the FODMAP diet that is sustainable to improve quality of life (Tuck, C., & Barrett, J., 2017). Quality of life is important within this diet because it can be restrictive and being social/eating out is important to most. Following the FODMAP diet can be difficult at first but if done successfully and a person understands their trigger foods, they will be able to be confident and more sociable in the food setting around others. It is important to understand that portion sizes make a difference as well and should be routinely followed even once the trigger food(s) is identified.

Below is a helpful diagram summarizing the above points.

(Tuck, C., & Barrett, J., 2017)

Is the FODMAPs Diet for Me?

The FODMAPs diet is considered extremely useful and widely used by dietitians when dealing with IBS or similar symptoms. If you are already noticing that some foods you eat often cause some of these symptoms then trying out the FODMAPs routine might be useful to nail down those trigger foods. The FODMAPs diet can also mask other underlying conditions so use it with caution. IBS symptoms are similar to Coeliac’s Disease and Non-Coeliac Gluten Sensitivity (NCGS), therefore, using the FODMAPs diet might not aid you in eliminating these symptoms or you may become too restrictive if you’re not seeing results. Coeliac's disease takes place in the small intestine, whereas IBS is a large intestinal (colon) issue. NCGS does not have a clear cut understanding of why it causes symptoms but from what is known, it does not physically damage the small or large intestine (Mayo Clinic Staff, 2019). Working closely with a registered dietitian to narrow down if you are struggling with IBS or other diseases/sensitivities is crucial so that you are not masking the initial problem if choosing to follow the FODMAPs diet.

Barrett, J. S. (2017). How to institute the low-FODMAP diet. Journal of Gastroenterology and Hepatology, 32, 8–10.