How does the low FODMAP diet work?
The low FODMAP diet is an elimination diet used to manage gastrointestinal symptoms like bloating, gas, and diarrhea. Low FODMAP stands for a diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols. These compounds are all types of carbohydrates, specifically types of sugars, sweeteners, and fiber that tend to not be digested as well by our bodies in our small intestine. Instead, they travel through the gastrointestinal (GI) tract to be digested by the bacteria and microbes residing further down in our colon. As these compounds travel through our gut, they attract water. As they are broken down by bacteria (a process called fermentation), this creates gas in the form of carbon dioxide, hydrogen, or methane. This gas can contribute to feelings of bloating, pain or discomfort, and constipation. The influx of water can contribute to diarrhea or looser, more frequent bowel movements(1,2,3).
Different food sources as well as production of gas during fermentation has the potential to alter the gut microbiome (all the bacteria, fungi, viruses, and other microbes that naturally reside in our gut) by altering the environment that they reside in. This alteration in the gut microbiome is called dysbiosis, which basically means the microbe community is off-balance. Dysbiosis can contribute to GI symptoms. The gut microbiome interacts with and helps regulate the network of nerves in the lining of the gut (called the Enteric Nervous System, or “little brain” of the gut) that regulates motility or movement of the gut, secretions, and absorption of food4. Thus, if there are changes to the gut microbiome, this can alter the regulation of GI movements and secretions, leading to symptoms like diarrhea, constipation, and pain or discomfort.
Therefore, when eliminating low FODMAPs in people that are sensitive to the effects of these foods, you will be eliminating foods that contribute to bloating, diarrhea, discomfort, or overall dysbiosis of the gut, thereby managing and getting relief from these GI symptoms.
It is important to note that foods high in FODMAPs are not bad for everyone. High FODMAP foods tend to be nutritious, high-fiber foods that can be good for our health and our gut. Only in people who are more sensitive to these high FODMAP foods or the effects of their fermentation do they tend to cause GI distress.
What foods can I eat on the low FODMAP diet?
As mentioned, the low FODMAP diet stands for low fermentable oligosaccharides, disaccharides, monosaccharides and polyols. The FODMAPs can be further broken down into 5 major food components: lactose, fructose, fructans, galactans, and polyols. Polyols are sugar alcohols like sorbitol, mannitol, maltitol, xylitol, isomalt that occur naturally in some fruits as well some manufactured products like chewing gum or mints. The remaining low FODMAP groups are sugars or starches common in many plant foods.
Someone on a low FODMAP diet should avoid foods that have lactose like milk, cheese, and yogurt; wheat and wheat products; certain fruits including stone fruits (have a pit in the core like mangos or peaches), apples, pears, and dried fruits; certain vegetables such as asparagus, cauliflower, mushrooms, onions, garlic, and artichokes(1); as well as beans including soybeans and soy products; legumes; cashews and pistachios; and sweeteners such as high fructose corn syrup and honey(5).
Since there are so many foods from different food groups that are eliminated on a low FODMAP diet, there are many resources that can help people keep tract of low FODMAP foods, find low FODMAP recipes, and more:
Classifications of low/high FODMAP foods and barcode scanning
- Monash University App (https://www.monashfodmap.com/)
- Fig (https://foodisgood.com/) – has low FODMAP filter
- Fast FODMAP Lookup & Learn (https://www.fastfodmap.com/)
Recipes, meal plans, and other low FODMAP information
- FODMAP Everyday (https://www.fodmapeveryday.com/resources/)
- Kate Scarlata (https://www.katescarlata.com/fodmaps-101)
Low FODMAP meal delivery services
- Modify Health (https://modifyhealth.com/collections/low-fodmap-diet-meal-delivery)
- Epicured (https://mmm.epicured.com/low-fodmap-diet)
- Low FODMAP grocery delivery services
- Thrive Market (https://thrivemarket.com) – has low FODMAP filter
- Fody (https://www.fodyfoods.com/)
How do I get started on the low FODMAP diet?
The low FODMAP diet is comprised of three phases: the elimination phase, the reintroduction phase, and the maintenance phase.
Phase One: First, low FODMAP foods are completely eliminated from the diet for 2-6 weeks until symptoms improve and the gut is at its most optimal health. This phase is not meant to be permanent. Work with your dietitian to determine the duration that is best for you for this elimination phase.
Phase Two: Next, you will reintroduce the different low FODMAP food groups. You will gradually increase the amount of a low FODMAP food and record your symptoms, if you have any. You will then give your gut a few days rest by continuing the strict low FODMAP elimination before reintroducing the next food group. The duration of this phase varies but on average can take about 8 weeks(5).
Phase Three: The maintenance phase takes the information you learned in phase two about the low FODMAPs that do or do not contribute to your symptoms to build your long-term eating patterns. You will limit your food triggers while eating a greater variety of foods that do not contribute to GI symptoms.
Should I try the low FODMAP diet?
The low FODMAP diet is recommended only for certain GI conditions. It is supported specifically in the treatment of irritable bowel syndrome (IBS) and small intestine bacterial overgrowth (SIBO)(5), but also can give some people with other digestive conditions, such as chronic diarrhea or uncomfortable bloating and gas, relief as well. The low FODMAP diet has been found to help reduce symptoms for 86% of people with IBS or SIBO(1). The low FODMAP diet will not cure or treat these conditions but is helpful in symptom management and relief.
The low FODMAP diet is not for everyone with IBS or SIBO. This diet should not be undertaken by anyone with an eating disorder or history of an eating disorder due to its restrictive nature. This diet is also not recommended for people with already highly restrictive diets due to allergies or following a vegan or vegetarian diet(6), or for someone who is already malnourished. Talk to a dietitian before initiating to see if this diet is right for you.
Low FODMAP can help to reduce the number of bowel movements by increasing transit time in the gut. Therefore, low FODMAP tends to be more beneficial for people with IBS-D. For people with IBS-C on low FODMAP, it is imperative to get adequate fiber from low FODMAP foods to keep bowel movements regular. Still, low FODMAP is indicated for and can be helpful for both types of IBS(3).
In conclusion, the low FODMAP diet is not for everyone, but can be a powerful tool for many people in managing and finding relief from GI symptoms. GI symptoms can be uncomfortable and disrupt day to day life, so if you are ready to take a nutrition approach to managing your symptoms, ask your dietitian if the low FODMAP diet could be right for you.
If you are diagnosed with a GI condition and would like more support, Avance Care is starting a free, quarterly support group for people with a variety of GI conditions. Whether you are newly diagnosed or have been living with IBS or another GI condition for many years, this group can help you with your GI symptom management. Join the support group email list by filling out the interest form below and someone will be in touch soon to get you started.
Avance Care Support Group Interest Form
References:
- Johns Hopkins Medicine. (2023). FODMAP Diet: What You Need to Know. Retrieved from https://www.hopkinsmedicine.org/health/wellness-and-prevention/fodmap-diet-what-you-need-to-know
- Dempster, J. (2018). Low FODMAP Diet 101: What you need to know to get started. Retrieved from https://thedempsterclinic.com/fodmap-diet-101/
- UCLA Health. (2021). Nutrition for IBS: FODMAPs and Beyond | Natalie Manitius, MPH, RDN | UCLA Digestive Diseases [Video]. YouTube. Retrieved from https://www.youtube.com/watch?v=yMdvsAGzLmQ
- Vicentini, FA, Keenan, CM, Wallace, LE, et al. (2021). Intestinal microbiota shapes gut physiology and regulates enteric neurons and glia. Microbiome.
- Cleveland Clinic. (2022). Low FODMAP Diet. Retrieved from https://my.clevelandclinic.org/health/treatments/22466-low-fodmap-diet
- Gelsomin E. (2020). The Lowdown on the Low FODMAP Diet. Retrieved from https://www.health.harvard.edu/blog/the-lowdown-on-the-low-fodmap-diet-2020072720662#:~:text=There%20is%20also%20concern%20that,energy%20source%20for%20beneficial%20bacteria.
