The Low FODMAP Diet is a special dietary plan which is used to help alleviate the symptoms of IBS (Irritable Bowel Syndrome). It was originally developed by researchers at the Monash University in Australia and it has helped patients around the world find relief from many of the difficult and stressful gastrointestinal symptoms of IBS.
Before we move on to answer the most frequently asked questions on the Low FODMAP Diet and IBS, there are two very important things that we need to stress:
- The low FODMAP diet is a specialized diet which consists of various stages and should only be followed under the guidance and supervision of an experienced health professional, preferably a registered dietitian who is specifically trained.
- The low FODMAP diet is not a lifetime or long-term diet. It is used for specific reasons and therefore has a specific timeline. In addition, the first part of the dietary plan is highly restrictive and if followed for a long time, it could possibly lead to significant nutritional deficiencies.
What are FODMAPs?
The word FODMAP is an acronym of the words Fermentable Oligosaccharides, Disaccharides, Monosaccharides And Polyols. The last four words (oligosaccharides, disaccharides, monosaccharides, polyols) are a group of simple carbohydrates which are not fully absorbed in our small intestine. They slowly move through it absorbing water along the way and when they reach the large intestine, they are fermented by the bacteria that live there. That’s why they are called fermentable.
Simply put, FODMAPs are a group of sugars that are not properly digested in our gut and are fermented by gut bacteria.
Which foods contain FODMAPs?
FODMAPs are very common and are found in many of the foods we eat like fruit, vegetables, grains and dairy products.
- Oligosaccharides refers mainly to fructans and galactooligosaccharides (GOS). Fructans can be found in grains like wheat, barley and rye, in fruit like watermelon, nectarines and peaches and in vegetables like onions, leeks and garlic. GOS can be found in most legumes and in some nuts like pistachios and cashews.
- Lactose is the main disaccharide in the FODMAPs family. It is found in most dairy products like milk, yogurt and many kinds of cheese.
- Fructose is the monosaccharide that should be avoided in a low FODMAP diet. It can be found in many fruit and vegetables like apples, pears, peas and asparagus. It is also found in excess in dried fruit and fruit juices and also in honey and products with HFCS (High-Fructose Corn Syrup).
- Polyols refers to a sub-group of sugars which are naturally found in many fruit and vegetables like apricots, plums, cauliflower and mushrooms. Many of them, like maltitol, mannitol and sorbitol, are also used by the food industry as added sweeteners.
For more information on what to eat and what to avoid when following a low FODMAP diet, you can check out an extensive list of foods here. You’ll also find some helpful general guidelines.
What is IBS?
Irritable Bowel Syndrome (IBS) is a functional gastrointestinal disorder with symptoms that are not caused by abnormal pathology in the gastrointestinal tract. It is estimated that 1 in 7 adults is affected by IBS at some point in their lives and the majority of them are women. It is usually a lifelong condition with alternating periods of subsiding and relapsing symptoms.
What are the symptoms of IBS?
Symptoms vary among patients and so does their intensity. The most common symptoms are:
- changed bowel habits (diarrhea, constipation or a combination of both)
- bloating and distension
- excess wind (flatulence)
- abdominal pain
Those symptoms tend to subside after bowels are emptied and they are usually exacerbated by stress. Since they are also a source of stress and tension, patients may enter a vicious circle which is hard to break.
How is IBS diagnosed?
There are no diagnostic tests for IBS. Since there are no abnormalities of the digestive system, the diagnosis is made after a complete, detailed medical history is taken and after several other conditions have been excluded. However, it is really important not to self-diagnose. The common symptoms of IBS may be an indication of other, sometimes serious conditions which only a medical professional can rule out.
How do FODMAPs affect people with IBS?
FODMAPs pass through the small intestine without being properly digested. They reach the large intestine having absorbed water which causes the intestinal walls to stretch. Additionally, the gut bacteria start fermenting them, producing gases that make the gut expand even more. This is a normal digestible procedure that happens to all people who eat foods with FODMAPs. But people with IBS have a really sensitive gut and all this stretching and extension causes symptoms of discomfort, abdominal pain and changes in bowel movement.
It is important to understand that FODMAPs do not cause IBS symptoms. They just trigger the symptoms to people with high sensitivity or worsen already existing ones.
Stages of the low FODMAP diet
After a patient is diagnosed with IBS, their doctor may suggest following a low FODMAP diet to help alleviate their symptoms and discover the foods that mostly trigger them. This should be done under the guidance of a registered dietitian with specific training on the low FODMAP diet who will guide them through the stages of the dietary plan.
Stage 1: Elimination (2-6 weeks)
During the first stage of the diet, all foods high in FODMAPs should be eliminated. The patient should follow a diet with foods low in FODMAPs, as balanced and nutritious as possible. They should also follow a generally healthy lifestyle and try, if possible, to also eliminate known stressors in their everyday life. At the end of this stage, the patient should be almost symptom-free.
Stage 2: Reintroduction (8-12 weeks)
During the reintroduction phase, the different categories of FODMAPs are gradually added to the daily meals. Each week, only one food containing a particular group, e.g. polyols, is added on three non-consecutive days. The quantity slowly increases in order to test how much is well tolerated. Common symptoms are monitored after each trial and if there is no adverse reaction, the patient can move on to the next. If, however, common symptoms are worsened, the testing of this particular group of FODMAPs is discontinued and the patient needs to wait until the symptoms are resolved. Then, they can continue to the next group.
Stage 3: Personalized diet plan (long-term)
At the end of the reintroduction phase, the dietitian has a clear picture of the trigger foods that worsen the patient’s symptoms. They can now integrate foods from all FODMAP groups that were well tolerated during the trials and create a personalized diet plan that fits the patient’s individual needs and helps eliminate their IBS symptoms.
Are there risks involved?
The low FODMAP diet is a restrictive dietary plan that comes with minor risks.
- Avoidance of dairy products can create difficulties in meeting Vitamin D and Calcium requirements. The patient should be advised and encouraged to switch to lactose-free dairy products and consume sufficient quantities of cheese types low in lactose but high in calcium like parmesan.
- The daily intake of fiber may suffer as a result of removing foods like whole grains and certain fruit and vegetables from the diet. Low FODMAP but rich in fiber foods should be included in the diet like oatmeal, oranges, spinach, etc.
- FODMAPs are natural prebiotics, which means they encourage the growth of many good bacteria in our gut. When we remove them from our diet, we could actually “starve” those bacteria and cause their numbers to be reduced in the long run. That’s one of the main reasons we shouldn’t follow such a restrictive diet for a long time.
The guidance and careful planning of a dietitian can ensure the replacement of eliminated foods with suitable alternatives which can adequately cover all nutritional needs.
Does the Low FODMAP diet work?
Several researches conducted by the Monash University and also by other researchers and medical experts have associated the low FODMAP diet with reduced gastrointestinal symptoms, reduced fatigue and symptom-generated anxiety, increased happiness and vitality and improved quality of life. Research also indicates that a diet low in FODMAPs has greater benefits than general dietary advice. However, the management of IBS syndrome with the low FODMAP diet is fairly new and the long-term effects as well as the risk of bias remain to be studied.
https://www.ncbi.nlm.nih.gov/pubmed/30644587
https://www.ncbi.nlm.nih.gov/pubmed/29159993
https://www.ncbi.nlm.nih.gov/pubmed/29129233
Resources
The Monash University website has many resources on FODMAPs and IBS for patients, dietitians and healthcare providers.
You can also find lots of information about Irritable Bowel Syndrome at the following websites.
https://www.nhs.uk/conditions/irritable-bowel-syndrome-ibs/
https://www.niddk.nih.gov/health-information/digestive-diseases/irritable-bowel-syndrome
