When the Low-FODMAP Diet Doesn't Work for IBS

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The low-FODMAP diet was developed as a way to offer people who have IBS a dietary approach for managing the disorder. Even though the underlying causes of IBS are complex and not completely understood, the American College of Gastroenterology advises that the diet can be quite helpful in significantly reducing symptoms.

The good news is that approximately 75% of people who attempt the low-FODMAP diet are able to successfully incorporate it into their IBS toolkit. Unfortunately, that is not helpful if you are someone who falls into the other 25%.

If a low-FODMAP diet didn't work for you, you may feel confused and frustrated, and wonder if you can do anything to help your IBS symptoms. Luckily, there is hope.

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How to Avoid FODMAPs to Lessen IBS

Find Out What Went Wrong

Before you look into alternative treatment approaches, take a moment to think about whether or not you had the necessary conditions in place to optimize your chances for success on the diet. Here are a few things for you to consider:

Did you work with an appropriately trained dietary professional? The American College of Gastroenterology states in their 2021 clinical guidelines for IBS that it is important to work with a properly trained GI dietitian because:

  • The low-FODMAP diet is complicated.
  • The potential for nutritional deficiencies exists.
  • The three phases of the diet need proper counseling (limitation of FODMAPs, reintroduction of foods while assessing symptoms, and creating a long-term and sustainable diet plan).

If a dietitian is not available or is too expensive, the ACG asserts that it is still important to do the diet in a medically responsible manner. The ACG also advises that the low-FODMAP diet still needs more quality research, but that it is worth trying.

How well did you do adhering to the diet guidelines? The low-FODMAP diet can be quite challenging to follow. For best results, you should go through a full elimination phase, in which you avoid all foods that are high in FODMAPs and only eat foods that are low in FODMAPs.

Many common foods, such as wheat, garlic, and onions, are high in FODMAPs. If you took a casual approach to following the diet or had a lot of "slips," you may not have provided yourself with the conditions necessary for optimal symptom improvement.

If this is the case for you, you may want to give the diet another try, with a renewed commitment to totally eliminating and then systematically reintroducing FODMAPs.

Did you try long enough? As of now, research has not identified exactly how long one should be on the diet in order to see results. The ACG recommends that the first phase last for two to six weeks.

If you are not experiencing significant symptom relief but have been on the diet for less than six weeks, you may want to try a little longer to see if six weeks of restricting high-FODMAP foods from your diet makes a difference in terms of your response.

Try Other Options

If you worked with an appropriate dietary professional, adhered strictly to the requirements of the elimination phase, and kept it up for a good six weeks and still saw little improvement in how you feel, give yourself a pat on the back for trying your best.

Do not spend a second blaming yourself. Even in laboratory conditions, the diet does not work for every person who has IBS. Here are some other options that you can look into to find symptom relief.

Talk to Your Doctor

Maybe your motivation in attempting the diet was to try a "natural" approach and to avoid taking medications for your symptoms. If that is the case, it might be time to make an appointment with a gastroenterologist to find out what medical options are available to you.

Over the past few years, several medications have been FDA-approved for the treatment of IBS. Your doctor will make a full assessment of your symptoms and may choose to offer you a prescription that they think would be of help to you.

IBS Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Man

Ask Your Doctor to Rule out SIBO

Small intestinal bacterial overgrowth (SIBO) has been found to be a contributing factor to symptoms in a subset of people who have IBS. One possible telltale sign of the presence of SIBO is that your symptoms occur within 90 minutes of eating.

The condition is diagnosed through the use of a hydrogen breath test. In order for the test to be accurate, you need to return to eating foods that are high in FODMAPs, as the low-FODMAP diet runs the risk of sending the bacteria into temporary dormancy.

If the breath testing confirms that SIBO is present, your doctor may choose to treat you with one or several rounds of antibiotics. These specific antibiotics are unlike antibiotics you may have taken in the past, as they act predominantly in your small intestine to reduce the number of bacteria that may be present there.

Because of this local effect, these antibiotics typically do not cause many side effects and have little to no effect on the beneficial bacteria within your large intestine.

Ask Your Doctor to Rule Out Other Health Problems

One reason the low-FODMAP diet may not work is that you may not have IBS but actually have another disorder. Your doctor may need to do more tests, or you may need to go to a specialist. Other possible diagnoses include:

Work With Your Dietary Professional

If you weren't already utilizing the services of a dietary professional, now might be the time to do so. And if you did work with such a professional and felt a good sense of rapport, it might be beneficial to continue on.

Your dietary professional may help you to identify if there are any factors contributing to your poor response to the diet and help you to problem-solve strategies to address other possible factors that may be contributing to your symptoms.

Such a professional can also help to determine which foods you tolerate best, while taking into account your complete nutritional requirements and food preferences. This may give you some relief as you seek out other forms of IBS treatment.

Identify Other Possible Food Triggers

FODMAPs are carbohydrates found in common foods that have been scientifically shown to contribute to IBS symptoms by increasing fluid and gas in the colon. However, this does not mean they are the only foods that might trigger unwanted digestive symptoms.

On your own, or working alongside a dietary professional, you may want to try following an elimination diet that targets foods that have a reputation for being IBS triggers. You will see that some of the foods on the list are foods that you may have already eliminated when you were following the low-FODMAP diet.

The foods most typically recommended for restriction are:

  • Alcohol
  • Coffee and other caffeine-containing drinks
  • Corn
  • Dairy
  • Eggs
  • Gluten
  • Soy

Although some sugar is allowed on the low-FODMAP diet, you may find that your body does not tolerate sugar well. As challenging as it may be, you may want to try the elimination of foods containing added sugar and assess what effect that has on your symptoms.

Fried foods, greasy foods, and large meals can all be hard on your digestive tract. You may feel better if you eat smaller meals throughout your day (although a large breakfast may help to ease constipation). Avoid fatty junk foods and be sure to eat foods that contain healthy fats.​

Last, you may want to talk to your doctor about being assessed for true food allergies, which are the immune system's reaction to certain foods.

The American College of Gastroenterology (ACG) recommends that allergy testing only be performed if you have a definite and reproducible reaction to the same foods consistently. Otherwise, they warn that the tests can yield many false positives, confusing the issue.

Try a Mind/Body Treatment

It may be that there are factors beyond food that are contributing to the severity of your symptoms. Stress can be a major trigger for digestive symptoms.

Mind/body treatments may be helpful in calming your system as you deal with the stress associated with having IBS. Cognitive behavioral therapy (CBT), hypnotherapy, and mindfulness meditation are all mind/body treatments that have research support as effective IBS treatments.

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  2. Nanayakkara WS, Skidmore PM, O'Brien L, Wilkinson TJ, Gearry RB. Efficacy of the low FODMAP diet for treating irritable bowel syndrome: the evidence to date. Clin Exp Gastroenterol. 2016;9:131-42. doi:10.2147/CEG.S86798

  3. Ghoshal UC, Shukla R, Ghoshal U. Small intestinal bacterial overgrowth and irritable bowel syndrome: A bridge between functional organic dichotomy. Gut Liver. 2017;11(2):196-208. doi:10.5009/gnl16126

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