The low-FODMAP diet probably does not roll off the tongue like other diet plans. FODMAPs, also known as Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols, is a dietary approach commonly prescribed for those suffering from digestive issues. Consider trying this diet if you have Irritable bowel syndrome (IBS), bloating, gas and other gut concerns. While some people may have a clear understanding of what this diet is all about, today’s post will review the basics of the FODMAP diet. I will review its history, what it is, why it is used, and how to get started. Stay tuned for my later post where I’ll review the FODMAP elimination and reintroduction process in more detail.
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How Did the low FODMAP Diet Come About?
A research team led by Dr. Peter Gibson, the Director of Gastroenterology at Monash University located in Melbourne, Australia, designed the low FODMAP diet. The first research trial on the effectiveness of this diet to manage IBS was published in 2006 by Gibson and Dr. Sue Shephard. However, the connection between poor absorption of certain carbohydrates and gastrointestinal symptoms has been evidenced since the 1980s.
Throughout the past decade, research clearly shows that the low FODMAP provides significant relief for many digestive disorders.
What Are Fermentable Carbohydrates?
To simplify the concept of FODMAPs, I use the term “fermentable carbohydrates.”
The “ODMP” in FODMAPs describe different chain lengths and types of carbohydrates (oligo= more than 2, di= 2, mono= 1, polyols= sugar alcohols). When a carbohydrate is particularly fermentable, this means that bacteria in the digestive tract enjoy “eating” them. When bacteria eat these foods, they release gas amongst other metabolites. In some cases, bacterial fermentation is health promoting, but in other cases it produces digestive distress (i.e. gas, bloating, pain, loose stools, etc.)
The most fermentable carbohydrates include lactose, fructose, sorbitol, mannitol, fructans, and galacto-oligosaccharides (GOS). Labs measure the fermentability of hundreds of commonly consumed foods. The fermentability score of foods is updated overtime so it is important to have an updated FODMAP food list.
Here is a quick and incomplete list of examples of foods that fall into each category of fermentable carbohydrate:
- Fructose: Honey, Apples, Mango, Pear, Watermelon, High Fructose Corn Syrup
- Fructans: Artichokes (Globe), Artichokes(Jerusalem), Garlic (in large amounts), Leek, Onion, Shallots, Wheat, Rye, Barley, Inulin, Fructo-oligosaccharides
- Lactose: Milk, ice cream, custard, dairy desserts, condensed and evaporated milk, milk powder, yogurt, soft unripened cheeses (eg. ricotta, cottage, cream, mascarpone).
- Galacto-Oligosaccharides (GOS): Legume beans (eg. baked beans, kidney beans, borlotti beans), Lentils, Chickpeas
- Polyols: Apples, Apricots, Nectarines, Pears, Plums, Prunes, Mushrooms, sorbitol, mannitol, xylitol, maltitol and isomalt
How Does the Low FODMAP Diet Help Improve Symptoms?
To answer this question, let’s start with why high FODMAP foods trigger symptoms. For starters, the fermentability of these foods create excess gas production in the digestive tract. Gas is the natural byproduct of bacterial fermentation. Additionally, FODMAPs have an osmotic effect in the bowl, which means they pull in extra fluid. The excess gas and fluid produces distension in the bowl, triggering pain, bloating, and changes in gastrointestinal motility (e.g. diarrhea or constipation).
Some FODMAP foods are completely indigestible to humans as we lack of the enzymes necessary to break them down. These include fructan and galactan fibers. Specific examples of these fibers are lentils, beans, broccoli, and wheat. Exceeding a specific load produces digestive problems in most people.
Lastly, polyols, also known as sugar alcohols, produce a laxative effect in the body when consumed in excess. This effect is due to their large molecular size and osmotic effect, resulting in loose stools or diarrhea.
Everyone is different and the low FODMAP often requires individual tailoring. However, following this elimination plan for 2 to 4 weeks results in improvement in 74% of people with IBS.
What Steps Do I Take To Start on the Low FODMAP Diet?
First, learn the diet’s details. Understanding the basics of the dietary changes helps alleviate the stress dietary changes often produce. Review educational resources available free online including material from world-class FODMAP Dietitians like Kate Scarlata and Patsy Catsos. There are also many books that teach about the FODMAP diet including The Complete Low-FODMAP Diet: by Dr. Sue Shepherd and IBS—Free at Last! by Patsy Catsos.
Second, familiarize yourself with the high FODMAP foods. Check out an updated list from a credible source or download the Monash University Low FODMAP Diet app ($7.99, but all proceeds go back into research).
Lastly, talk to a FODMAP-trained dietitian (myself included) to guide you through the phases of the FODMAP diet. While the plan may appear straightforward, most people find unique responses to different foods and need specific diet-tailoring. Learn dietary tweaks in the case of undesired results. Use this diet short-term, followed by a guided reintroduction process.
Contact me today to set up an appointment and learn more about the low FODMAP diet.