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A low-FODMAP diet is often recommended to alleviate symptoms of irritable bowel syndrome (IBS).
The diet is low in fermentable carbohydrates which can trigger symptoms such as stomach pain, diarrhea, and bloating in people with IBS.
This article explains what to eat and avoid on a low-FODMAP diet and provides a sample 3-day low-FODMAP diet menu.
What are FODMAPs?
FODMAP stands for fermentable oligo-, di-, and monosaccharides and polyols (1).
These carbohydrates are poorly absorbed and pull water into your digestive tract. Your gut bacteria also ferment them, contributing to common symptoms of IBS.
For this reason, a low-FODMAP diet has been traditionally recommended to manage IBS symptoms and remains the most evidence-based diet for IBS (2).
Indeed, studies suggest that the low-FODMAP diet can relieve symptoms in 50–80% of people with IBS (3).
Common IBS symptoms include (7):
- abdominal pain
- excessive gas
FODMAPs are naturally found in a variety of foods, and many foods contain more than one type.
Here are the primary sources of FODMAPs (9):
- Oligosaccharides: artichoke, asparagus, barley, beetroot, broccoli, brussels sprouts, cabbage, garlic, leek, onion, rye and wheat cereals, chickpeas, lentils
- Disaccharides: lactose-containing products, including milk, yogurt, and soft or fresh cheeses
- Monosaccharides: fructose-containing foods, including apples, dried fruit, fruit juice, mango, pears, sugar snap peas, honey, watermelon
- Polyols: apricots, avocado, cherries, peaches, prunes, cauliflower, mushrooms, sweeteners ending in “-ol,” such as sorbitol and xylitol
While restricting FODMAPs has been shown beneficial for people with IBS, it isn’t for everyone, including those who are at risk for malnutrition, who are food insecure, or who have an eating disorder or uncontrolled mental illness (2).
Low-FODMAP foods to eat
Although FODMAPs are present in a variety of foods, you can still enjoy a varied diet by choosing low-FODMAP foods.
Low-FODMAP foods include (9):
- Fruits: bananas, berries, cantaloupe, durian, grapes, grapefruit, honeydew melon, kiwi, lemon, lime, oranges, tomatoes
- Vegetables: bok choy, carrots, celery, chives, eggplant, green beans, lettuce, parsnip, pumpkin, green onion
- Grains and starches: gluten-free and spelt bread and cereal products
- Dairy: lactose-free milk and yogurt, and hard cheeses
- Proteins: beef, chicken, eggs, fish, pork, shellfish, turkey
- Nuts and seeds: peanuts, pecans, pine nuts, pumpkin seeds, sesame seeds, sunflower seeds, walnuts
- Oils: garlic-infused oil and olive oils
- Beverages: water, tea, coffee
- Condiments: maple syrup, soy sauce, mustard, spices without onion or garlic powder, salt, pepper, mayonnaise, and sweeteners, except sugar alcohols and other polyols
Because FODMAPs are present in protein-rich plant foods like beans and peas, it can be difficult to eat enough protein if you follow a vegan diet.
How to follow a low-FODMAP diet
A low-FODMAP diet is not a one-size-fits-all approach.
Each person will react differently to FODMAPs, depending on the type and amount consumed.
As such, an elimination diet strategy is best to identify which foods, and in what amount, trigger your symptoms.
Here are the steps to follow a low-FODMAP diet:
Step 1: Elimination
The elimination step involves eliminating the primary sources of FODMAPs from your diet until your symptoms become minimal to non-existent, which typically takes 4–6 weeks (10).
Doing so has been shown to improve symptoms in up to 80% of people with IBS who received support from a registered dietitian (11).
If you don’t experience symptom relief after 4–6 weeks of eliminating FODMAPs, a high-FODMAP food challenge can confirm whether your symptoms are truly due to FODMAPs or something different.
Some people may not respond during this phase due to poor dietary compliance, making counseling from a registered dietitian important to address any barriers.
It’s best to maintain a journal and document which foods you eliminated so you don’t lose track, especially since most foods do not list their FODMAP content.
Step 2: Reintroduction
The reintroduction phase involves reintroducing the high-FODMAP foods that you eliminated.
It’s normal to be hesitant about reintroducing foods after experiencing relief during the elimination phase, but it’s essential to avoid unnecessary food restrictions and increase diet variety.
Start with oligosaccharides, since these are highly fermentable and likely a significant contributor to bloating, abdominal pain, and excessive gas (1).
Oligosaccharides primarily include wheat and rye products, legumes, nuts, artichokes, onions, and garlic.
Introduce each food, one at a time, slowly over several days while you look for symptoms.
If you experience no symptoms after reintroducing a food, you can assume that food is not a trigger and then reintroduce the next.
For example, you may find that you’re not lactose intolerant and can tolerate dairy products just fine.
Conversely, if you do experience symptoms, you should remove the food from your diet.
However, complete elimination is not always necessary as you may be able to tolerate small amounts of a FODMAP food before it triggers symptoms.
The reintroduction phase can take 6–10 weeks, depending on your tolerance level.
Step 3: Personalization
All FODMAPs are potential IBS-symptom triggers, but not all FODMAPs produce the same symptoms in everyone.
Your diet must be personalized based on the FODMAP foods and the amounts that trigger your symptoms.
Foods that you identified to trigger severe symptoms should be eliminated going forward, whereas others that trigger mild-to-moderate symptoms may be OK every so often in small amounts.
The goal of the low-FODMAP diet is not severe restriction but to identify as many foods as possible that you can eat without severely triggering symptoms or triggering symptoms at all.
This helps increase the nutritional quality of your diet as well as improve your quality of life.
3-day sample low-FODMAP diet menu
Here’s a 3-day sample low-FODMAP diet menu for the elimination phase:
- Breakfast: scrambled eggs and gluten-free toast with margarine
- Lunch: tomato soup and gluten-free grilled cheese
- Snack: peanut butter and banana gluten-free wrap
- Dinner: grilled chicken salad drizzled with garlic-infused olive oil
Day 2 (vegan)
- Breakfast: breakfast quinoa made with almond milk and topped with maple syrup and blueberries
- Lunch: tomato soup and a gluten-free baguette
- Snack: soy protein isolate shake and a banana
- Dinner: vegan lasagna
- Breakfast: egg scramble and strawberry slices
- Lunch: hamburger on a gluten-free bun, potato wedges, and side salad
- Snack: string cheese sticks and grapes
- Dinner: baked salmon, white rice, and sauteed green beans
Helpful supplements for IBS and a low-FODMAP diet
Along with a low-FODMAP diet, several supplements can be helpful for managing IBS.
Unfortunately, getting enough fiber can be difficult since many FODMAP foods like beans, whole grains, and vegetables are rich in dietary fiber.
But not all fiber supplements are created equal and some are better tolerated than others.
Look for fiber supplementations that use psyllium husk or ispaghula, like this one from NOW Foods.
Women should aim to consume at least 25 grams of fiber per day and men should aim to consume 38 grams of fiber (14).
Probiotics are live bacteria that boost health when consumed in adequate amounts.
Eating a diet rich in prebiotics — a type of fiber that feeds the healthy bacteria in your gut like probiotics — supports a healthy gut and improves digestive health.
However, because many FODMAP foods are rich in prebiotics, people with IBS may have imbalances in their gut bacterial communities, which may contribute to symptoms (17).
Fortunately, supplementing with probiotics has been shown to significantly improve some IBS symptoms (18).
The most beneficial probiotic strains for alleviating IBS symptoms include Bacillus coagulans, Lactiplantibacillus plantarum, Saccharomyce boulardii, and Saccharomyces cerevisiae (19).
Avoid probiotic supplements that contain prebiotics like Jerusalem artichoke root or chicory root as these fibers contain FODMAPs.
While classified as a vitamin, vitamin D is more of a hormone.
More than 30 organs contain vitamin D receptors, to which vitamin D binds and exerts a variety of bodily functions related to bone health, blood sugar control, blood pressure regulation as well as immune and muscle function (20).
Like most of the population, low vitamin D levels are common among people with IBS.
Still, given the high prevalence of low vitamin D levels among people with IBS, vitamin D supplementation is a relatively inexpensive way to support healthy levels, especially since few foods are naturally good sources.
A vitamin D supplement that contains 1,000 to 2,000 IUs (25–50 mcg) is a good place to start.
Shop for vitamin D online.
The bottom line
FODMAPs are poorly absorbed carbohydrates that can lead to excessive fluid and gas accumulation in the digestive tract, resulting in bloating, abdominal pain, constipation, and diarrhea.
Fortunately, following a low-FODMAP diet can help alleviate symptoms in most people with IBS, and may also be beneficial for people with ulcerative colitis.
A low-FODMAP diet starts with an elimination phase in which you eliminate FODMAPs for 4–6 weeks before slowly reintroducing them and monitoring your symptoms so that you can identify foods that trigger your symptoms.
Along with a low-FODMAP diet, several supplements such as fiber, probiotics, and vitamin D can be beneficial for IBS.