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Unraveling the Connection: IBS, Low FODMAPs, and Fructan Intolerance Explained

What is IBS?

Irritable bowel syndrome (IBS) is a multifactorial disorder that involves altered motility,

brain-gut interaction, intestinal microbiota, gut permeability, visceral sensation, and gut immune

activation. IBS affects 7% to 16% of individuals in the United States. IBS causes recurrent

abdominal pain and altered bowel habits commonly resulting in gas, bloating, abdominal

distension, and urgency. IBS is commonly categorized into four different subtypes: IBS with

diarrhea (IBS-D), IBS with constipation (IBS-C), IBS with mixed constipation and diarrhea

(IBS-M) and IBS without a significant pattern of abnormal stool (IBS-U). 1

What is low FODMAP?

Living with IBS can lead to decreased quality of life, social isolation, and work

performance interference. The low fermentable, oligosaccharide-, disaccharide-,

monosaccharide-, and polyol (FODMAP) diet has been the predominant diet treatment for IBS. 2

FODMAPs are short chain carbohydrates that are not properly absorbed in the gut which can

lead to gastrointestinal symptoms like cramping, bloating, and diarrhea. 3 FODMAPs are a

naturally forming sugar that can be found in a wide variety of foods. 4 The reducing the amount of FODMAPs in the diet has shown to improve symptoms of IBS. 3 The low FODMAP diet consists of three phases: elimination phase, challenge phase, and reintroduction phase. In the elimination phase,

high FODMAP foods are reduced from the diet for 2-6 weeks. In the challenge phase,

individuals identify triggers by incorporating one FODMAP group back into their diet at a time, testing serving sizes of each FODMAP group to identify tolerance levels. Lastly, in the reintroduction phase, individuals reintroduce the FODMAP foods that were not identified as triggers back into their diet.

What are Fructans?

In the elimination phase of the low FODMAP diet, individuals commonly find difficulty

eliminating fructans. A fructan is a molecule that consists of a chain of fructose sugar molecules

joined together with a glucose molecule at the end. Fructan is part of the oligosaccharide- group

in FODMAPs. When challenging fructans, the challenge groups are broken into 4 categories, this is because the portion sizes found in food greatly varies, and is found in a variety of food sources.

  • Fructan Grains: This category includes any typical bread products, pastries, and pizza dough. When identifying high fructan grains, one should look for wheat, barley, rye, and spelt in ingredient lists.

  • Fructan Fruits and Vegetables:

  • Onion

  • Garlic

Identifying a Fructan Intolerance:

A low FODMAP diet can help determine if individuals are having an intolerance to

fructan. As mentioned before, the low FODMAP diet eliminates, challenges and reintroduces

FODMAP foods in order to determine which foods are triggering. Due to the fructan group

covering a wide variety of foods, separating this group into subgroups can be beneficial.

As you challenge each fructan group, it is important to identify which foods you can and cannot tolerate. Individuals may find that some high fructan foods do trigger their symptoms (gas, bloating,

diarrhea, constipation, abdominal pain) while others do not. Keeping a journal or food log can

aid in identifying these foods and the serving sizes tolerated. And working with a dietitian who specializes in the FODMAP diet can help you identify your tolerance levels. Once the challenging phase is completed, individuals can slowly reintroduce the foods that do not trigger their symptoms back into their diet. 5

High Fructan Foods

*note that FODMAP levels of foods are continuously tested and serving sizes may change. This is not a full comprehensive list of fructan containing foods.

Limit the below foods to the listed portion size. Each serving size listed is the serving size that is considered low FODMAP. Anything above that is considered to have a high amount of fructans.






Wheat Bran, uncooked 1/2 TBSP

Asparagus, 1 spear

Apricot, dried, 0

Vegan Cheese, cheddar, coconut oil based, 2 slices

Baked Beans, 1 Tbsp

English Muffin, 1

Beets, 2 thin slices

Banana, ripe, 1/3 medium

Vegan cheese, soy based, 2 slices

Navy Beans, dried, 1/4 cup

Rye Bread, 0

Green bell pepper, 1/2 cup

Cranberries, dried, 1 Tbsp

Cream cheese, garlic and herb, 0.7 oz

Black Beans, canned, 1/4 cup

Wheat bread, 0

Orange Bell Pepper 1/4 cup

Cranberries, raw, 1/2 cup

Condensed milk, coconut, 2 Tbsp

Beans, Cannellini, canned, 1/3 cup

Cornflakes, 1/2 cup

Brussel Sprouts, 1.87 oz

Cantaloupe, 3/4 cup

Coconut milk, inulin, 0

Lima Bean, dried, 1/4 cup

Couscous, 0

Red Cabbage, 3/4 cup

Dates, Medjool, 1

Oat milk, 6 Tbsp

Beans, Pinto, canned, 2 Tbsp

Barley, 0

Savoy Cabbage, 1/2 cup

Figs, dried, 0

Beans, Kidney, canned, 3 oz

Amaranth Flour, 0

White Daikon, 1/2 cup

Goji Berries, 3 tsp

Cashew, 0

Barley Flour, 0

Poblano Pepper, 1 medium

Grapefruit, 2.8 oz

Pistachio, 15 nuts

Coconut Flour, 0

Red Chili Pepper, 1 medium

Honeydew melon, 1/2 cup

Split Peas, 0

Einkhorn Flour, 0

Canned Corn, 1 cup

Passion Fruit, 2 medium

Tofu, silken, 1/4 cup

Wheat Flour, 0

Edamame, shelled, frozen 1/2 cup

White Peach, 2 Tbsp

Tofu, firm 6 oz

Bulgur, 2/5 cup

Jicama, 1/2 cup

Pear, green 0.2 oz

Farro, 1/3 cup cooked

Leek (bulb only), 1 Tbsp

Pineapple, raw 1 cup, dried (0)

Freekeh, 0

Okra, 7 Pods

Pomegranate Seeds, 1/4 cup

Wheat Pasta, 1/2 cup cooked

Onion, 0

Prune, dried, 0

Semolina, 0

Squash, Pumpkin, 1/3 cup

Raisin, 1 Tbsp

Wild Rice, 1 cup cooked

Squash, spaghetti, 1/2 cup cooked

Watermelon, 2 Tbsp

Wheat Tortilla, 1 small

Zucchini, 1/2 cup

While following a low FODMAP diet, it is important to ensure you are still

getting the nutrients your body needs. Working with a dietitian will help you to safely and

effectively navigate this process.


1. Academy of Nutrition and Dietetics.Nutrition Care Manual. [Irritable Bowel Syndrome].

v3=275335&ncm_toc_id=275335&ncm_heading=Nutrition%2520Care]. Accessed

[January 30, 2024].

2. Manning LP, Yao CK, Biesiekierski JR. Therapy of IBS: Is a low Fodmap Diet the

answer? Frontiers in Psychiatry. 2020;11. doi:10.3389/fpsyt.2020.00865

3. Syed K, Iswara K. Low-FODMAP Diet. [Updated 2023 Sep 4]. In: StatPearls [Internet].

Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from:

4. Cleveland Clinic. Could you have a fructan intolerance? Cleveland Clinic. January 4,

2024. Accessed January 30, 2024.

5. Riker C. Low fodmap: Riker Nutrition Consulting: United States. Riker Nutrition.

Accessed February 2, 2024.

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