Low FODMAP diets are a natural way to help improve symptoms or diseases affecting the gastrointestinal tract like irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD). 

What is a Low FODMAP Diet?

FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyol) is a term that describes a group of foods that contain undigestible nutrients that feed bacteria in the gut and a low FODMAP diet is a diet that limits or eliminates these foods. The goal of this diet is to limit FODMAP containing foods which are fermented by bacteria in the intestines. Fermentation of FODMAP containing foods may lead to increased gas production and negative effects like  bloating, distention, and exacerbation of Irritable Bowel Syndrome (IBS) (1). 

Who Can Benefit From a Low FODMAP Diet?

A low FODMAP diet is currently recommended and patients with symptoms of irritable bowel syndrome are the most common candidates. Adherence to a low FODMAP diet has been shown to improve common symptoms of IBS like abdominal pain, bloating, diarrhea, and gas (2). If you have not been "diagnosed" with IBS, the low FODMAP diet may still be beneficial if you are experiencing any of these symptoms. The low FODMAP diet has been shown to help up to 86% of patients after only 4 weeks adherence (3).

Another condition that may be improved by the low FODMAP diet in Small Intestinal Bacterial Overgrowth (SIBO). This condition results when health bacteria in the large intestine are overgrown and begin to populate other areas like the small intestine. Symptoms of SIBO can resemble IBS and include bloating, abdominal distention, gas, and constipation (4). The low FODMAP works to improve SIBO by starving the overgrown bacteria of the small intestine and ultimately normalizing the amount and location of bacteria, leading to improvement of symptoms. 

The Monash University Low FODMAP Diet:

The Low FODMAP diet was developed my Monash University, hence the name "The Monash University Low FODMAP Diet". The main foods eliminated in this diet are poorly absorbed carbohydrates found in many grains, vegetables, fruits, and dairy products (3). After the initial elimination of these foods, the diet’s effectiveness can be assessed by symptom reduction or may be viewed objectively by a healthcare practitioner with breath testing for gases that would be produced by high fermentation of FODMAPs (3). Although there is a long list of foods that are eliminated, there are plenty of alternatives to ensure adequate nutrition. The Monash Diet is listed below, with high FODMAP foods to be eliminated on the left and their low FODMAP alternatives that are OKAY to eat when following the diet on the right (3).

Are there any drawbacks to the low FODMAP Diet?

The low FODMAP diet seems to be fairly easy to implement and most people find it easy to find low FODMAP foods in the supermarket. One drawback is that some patients find that the diet is more expensive than a standard American diet. Although there is not much research in this area, it is proposed that a long-term low FODMAP diet may reduce the quality of the beneficial microorganisms found in the colon known as the microflora (2). This is due to the lack of fermentation of foods which in turn starves these microorganisms and causes them to die off. However, it may be beneficial to those with an overgrowth of the microorganisms in the small intestine, a condition known as small intestinal bacterial overgrowth (SIBO).   Concerns about the lack of nutritional adequacy are likely unwarranted as the low fodmap diet allows for consumption of healthy foods in each food group (2). 

References:

1. Halmos E, Chrstopherrsen CT, Bird AR, Shepard SJ, Gibson PR, Muir JG (2015) Diets that differ in their FODMAP content alter the colonic luminal microenvironment. Gut 64(1):93–100 https://www.ncbi.nlm.nih.gov/pubmed/term=Diets+that+differ+in+their+FODMAP+content+alter++the+colonic+luminal+microenvironment2. Meta Analysis. Accessed on October 12, 2017.

2. Marsh, Abigail, Eslick M, Enid, Eslick D, Guy (2016). Does a diet low in FODMAPs reduce symptoms associated with functional gastrointestinal disorders? A comprehensive systematic review and meta-analysis. European Journal of Nutrition 55: 897-906. https://link.springer.com/article/10.1007%2Fs00394-015-0922-1 Accessed on October 12, 2017. 

3. Barrett E, Jaqueline (2013). Extending Our Knowledge of Fermentable, Short-Chain Carbohydrates for Managing Gastrointestinal Symptoms. Nutrition in Clinical Practice 28 (3): 300-306http://journals.sagepub.com/doi/10.1177/0884533613485790#articleCitationDownloadContainer Accessed on October 12, 2017.

4. Grace E, Shaw W, Andreyev HJ. Review Article: Small intestinal bacterial overgrowth--prevalence, clinical features, current and developing diagnostic tests, and treatment. Ailment Pharmacol Ther. 2013 Oct;38(7):674-88. doi: 10.1111/apt.12456. Epub 2013 Aug 20.