The low FODMAP diet is for people with digestive problems like Irritable Bowel Syndrome (IBS). Although FODMAPs are types of carbohydrates, this is not your typical “low-carb” diet. The low FODMAP diet only limits carbohydrates that are “Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols.” Thank goodness they came up with an acronym!
For most people, FODMAPs are not a problem unless you eat too much of them (hence the jokes about beans and onions). But some people are extra sensitive, finding that FODMAPs trigger symptoms including abdominal pain, cramping, bloating, excess gas, constipation and/or diarrhea. And the more FODMAPs consumed over a period of time, say a meal or one day, the worse the symptoms are likely to be.
So how do these carbs wreak all this havoc? Well for some people, their intestines have a difficult time absorbing FODMAPs. So they continue their travels into the large intestine (colon) where they become fast food for the naturally-occurring gut bacteria. As the bacteria digest (ferment), a lot of gas is produced. They also attract water into the large intestine which can make people feel bloated and uncomfortable. Both the gas and the water can also cause abdominal pain, cramping, diarrhea and constipation.
The following types of carbohydrates are considered FODMAPs:
- Fructose: found in foods like honey, high fructose corn syrup, agave and some fruits
- Lactose: found in foods like chocolate, milk, yogurt and cottage cheese
- Fructans: found in foods like wheat, onions, garlic
- Galactans: found in foods like legumes (beans, lentils and soybeans), pistachios and cashews
- Polyols: found in sweeteners and fruits that have pits or seeds such as apples, avocados, cherries, figs, peaches and plums
The low FODMAP diet alleviates symptoms by eliminating the food supply for bacteria in the large intestine. In a study published in the journal, Gastroenterology, about three out of four people with IBS found that their symptoms improved immediately after beginning a low FODMAP diet. They felt the greatest symptom relief after 7 days or more on the plan.
The following animation video created by Monash University, the developers of the low FODMAP diet, explains how FODMAPs trigger symptoms associated with IBS and why the low FODMAP diet is an effective diet strategy.
How does the diet work?
At its simplest, the diet involves avoiding all five forms of FODMAP carbohydrates (fructose, lactose, fructans, galactans and sugar alcohols) for at least 6 weeks to see if your symptoms improve. If FODMAPs are the cause of your digestive distress, you’ll likely feel better within a matter of days.
Once your symptoms have improved, you can gradually reintroduce one FODMAP group at a time at a rate of one group per week. This will tell you how much, if any, you can tolerate. You may discover that you’re only sensitive to one or two FODMAP compounds and not all of them.
The goal of this reintroduction phase is to gradually widen the diet as much as possible to ensure you are getting many different kinds of nutrients and to prevent you from continuing with unnecessary food restrictions. Eventually, you may get to the point where even your initial trigger foods don’t cause the symptoms that they once did. The theory is that your overall immune system and gut microflora have improved, making it easier to tolerate some high FODMAP foods.
The ultimate goal of the low FODMAP diet is to get you to a place where you can eat a wide range of foods without experiencing symptoms.
Which foods are allowed and which are not?
Don’t despair… there are many foods that are still allowed on a low FODMAP diet. However, there is certainly a steep learning curve to decipher which foods are high in FODMAPs and what foods you could choose instead. There is also ongoing research into the FODMAP content of foods which can make it difficult to stay current.
For your convenience, I have compiled a list of foods that are high FODMAPs and another of low FODMAP foods. These lists are based on research from Monash University and are current as of January 20th, 2016. I will continue to update them as new research emerges.