The Low FODMAP Diet for IBS – Is It Helpful or Harmful?

By Dr. Kealy Mann, ND & Dr. Chelsey Corrigan, ND
November 27, 2020

Irritable Bowel Syndrome (IBS) is one of the most common gastrointestinal complaints, with approximately 1 in 10 people in North America affected. It leads to a wide variety of symptoms, including bloating, gas, constipation, diarrhea, abdominal pain, and cramping. This condition can impact the quality of life of those who suffer from it, including changes in mental health and social interactions.

Many people see their doctors for help with their digestive symptoms, and more recently, the low FODMAPs diet has become a standard recommendation to treat IBS. But, while this diet may help alleviate symptoms, we have to weigh the pros and cons of these dietary changes and ask, is this diet helpful, and what are the possible downsides?


What is a low FODMAP diet?

This diet came by its catchy name because of the types of dietary carbohydrates that it eliminates. The FODMAPs are Fermentable Oligosaccharides, Disaccharides, Monosaccharides, And Polyols. We should note that this diet does have quite a bit of research that indicates that it is one of the most effective diets for managing the symptoms of IBS. The low FODMAPs diet is known to reduce IBS symptoms such as gas, bloating, and variable bowel movements.

The low FODMAP diet helps to reduce the symptoms of IBS by reducing the fuels (fermentable carbohydrates) that feed bacteria in your gut. When you eat fermentable carbohydrates, these bacteria use this fuel to produce gases that then cause symptoms in your gut. These carbohydrates may also increase fluid levels in the small intestine, and these fluids, combined with the extra gasses, cause digestive symptoms for some patients with IBS.


When is the Diet Beneficial?

The low FODMAPs diet can give symptom relief to some who suffer from IBS. If the bacteria in your small intestine don’t have any fuel to ferment, they can’t produce the gasses that cause IBS symptoms. Removing fermentable carbohydrates can offer temporary relief and substantially reduce suffering.


When is the Diet Not Beneficial?

We highlighted why this diet could be temporarily beneficial for IBS sufferers, but there are downsides to following a low FODMAP diet, both in the short and long term. In the short term, this diet may lead to, or worsen constipation, because dietary fiber tends to be insufficient when you remove all of these carbohydrates from your diet. It also fails to address individual food sensitivities that may arise and are not uncommon in those suffering from IBS.

These dietary changes also fail to address the root cause of why someone developed IBS in the first place. Studies show that following a low FODMAP diet will not treat your IBS but only help temporarily alleviate symptoms. Unfortunately, many IBS sufferers find that once they start re-introducing foods back into their diet, their symptoms return.


What are the Risks of Following a Low FODMAP Diet?

The low FODMAP diet is relatively restrictive and eliminates many healthy foods that provide vitamins, minerals, and fiber. Following this diet long term may lead to some of the following effects:

  • Dysbiosis (bacterial imbalance): by reducing the fuel for harmful bacteria, you are also reducing the fuel for your helpful (“good”) bacteria. This can lead to an imbalance in your bacteria levels in your gut and affect your overall gut health. One study has demonstrated a decrease in levels of healthy bifidobacteria
  • Nutrient deficiencies: Let’s face it: getting enough vitamins and minerals in your diet can be a challenge, even when you eat a wide variety of foods. But when you eliminate a large number of healthy fruits and vegetables, nuts, and seeds, it makes the challenge that much more difficult. Long term dietary restrictions such as those included in the low FODMAPs diet may lead to, or worsen, deficiencies in vitamins and minerals.


If the low FODMAP diet isn’t the answer, what should you do if you have IBS?

IBS can cause significant distress and can be challenging to talk about, even with your physician or naturopathic doctor. But it’s important to note that food is not always the problem. To heal your IBS, it is essential to understand the caused your digestive symptoms, and it’s even more important to work with someone who can help you get to the bottom of your IBS. While the low FODMAP diet may provide short term relief for some, it may lead to long term side effects. Tests such as the SIBO breath test or a digestive health markers test may be appropriate and can help determine the causes of your symptoms and guide your health care provider on an evidence-based treatment plan to restore your digestive health.

If you have any questions or would like some further information about how testing may help you get to the bottom of your digestive concerns, contact us or book an appointment with one of our Registered Naturopathic Doctors.


In health,
Your Digestive Health Detectives
Dr. Kealy Mann, ND & Dr. Chelsey Corrigan, ND

Whole Medicine Naturopathic Clinic

525 March Rd.
Kanata, Ontario
K2K 2P4


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