FODMAP vs Gluten: What’s The Difference?

FODMAPs and gluten are not the same thing. While gluten is a protein found in wheat, rye, barley, and triticale, FODMAPs are fermentable carbohydrates found in a wide variety of foods, including many foods that also contain gluten. People with celiac disease must follow a strict gluten-free diet, while people with irritable bowel syndrome (IBS) may benefit from a low FODMAP diet.

Since foods like wheat contain both gluten and fructans (a type of FODMAP), people may mistakenly believe that gluten is causing their symptoms, while in fact, it's the fructans. This article will explore the difference between FODMAPs and gluten, the roles of gluten-free and low FODMAP diets, and when to choose low FODMAP vs gluten-free foods.

Gluten-Free vs FODMAPs

A gluten-free diet completely eliminates gluten (a protein), while a low FODMAP diet limits (but doesn't completely eliminate) FODMAPs. Both diets are designed to address specific health concerns, but while both diets share a common goal of improving digestive symptoms, they differ in their focus and underlying principles.

What is gluten?

Gluten is a protein found in wheat, barley, rye, and triticale. Common foods that contain gluten include bread, flour, pasta, breakfast cereals, and baked goods, although nowadays, there are often gluten-free versions of these foods available.

The gluten-free diet is essential for people with:

• Celiac disease: Celiac disease is an autoimmune disorder where your immune system mistakenly attacks the cells of your small intestine when you eat gluten, causing symptoms like diarrhea, abdominal discomfort, and bloating. Celiac patients must avoid wheat-based foods and follow a gluten-free diet to manage their symptoms. Around 1 in 100 Americans have celiac disease (around 1% of the population).

• Non-celiac gluten sensitivity (NCGS)/non-celiac wheat sensitivity (NCWS): Some people experience similar symptoms to celiac disease when they eat gluten but do not test positive for celiac disease. People with NCGS/NCWS (also called gluten intolerance) typically see an improvement in their symptoms with a dietary reduction of gluten, but there is currently no lab test for diagnosing it. Research has not yet confirmed that gluten induces symptoms, as many foods containing gluten also contain amylase-trypsin inhibitors (ATIs) and fructans (a FODMAP), which could also be responsible for the symptoms. Around 1% to 13% of the population may have NCGS, although lack of a diagnostic test makes knowing the exact number difficult.

• Wheat allergy: Like celiac disease, a wheat allergy involves the immune system. However, in the case of wheat allergy, many different wheat proteins (such as albumin, globulin, gliadin, and gluten) may be responsible for the symptoms. In addition, while they can include gut symptoms, symptoms are more likely to be allergy-like, including itching, swelling, or irritation in the mouth or throat, hives or rashes, or even anaphylaxis.

What are FODMAPs?

Unlike gluten, which is a protein, FODMAPs are carbohydrates. FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) are a group of carbohydrates that can be poorly absorbed in the small intestine and may cause digestive issues like bloating, gas, abdominal pain, and altered bowel habits in some people, particularly those individuals with IBS. 

Some people may experience IBS-like symptoms when they eat high FODMAP foods even if they don't have IBS. Even though they may not have IBS, they may still have a FODMAP sensitivity.

The Monash University low FODMAP diet, or FODMAP elimination diet, involves temporarily reducing or eliminating certain types of carbohydrates from the diet, including lactose, excess fructose, fructans, galactans or galacto-oligosaccharides (GOS), and polyols (sugar alcohols). 

Foods high in FODMAPs include:

• Wheat

• Onions

• Garlic

• Certain nuts/seeds

• Legumes and beans

• Certain fruits (such as apples and pears)

• Certain vegetables (such as celery and Brussels sprouts)

• Dairy products containing lactose

• Sweeteners like sorbitol and mannitol

Developed by Monash University, a low FODMAP diet is a 3-step diet used to help manage the symptoms of medically diagnosed IBS. These include the elimination phase, personalization phase, and the reintroduction phase. Some people prefer to follow a simplified FODMAP diet, which only eliminates the highest-FODMAP foods thought to be triggering symptoms. Up to 70% of people with IBS see symptom improvement on a low FODMAP diet.

Is gluten high FODMAP? 

No, gluten itself is not high FODMAP. It is a protein, while FODMAPs are carbohydrates. However, there is some overlap between gluten-containing foods and high FODMAP foods. The same grains (wheat, rye, barley, and triticale) that contain gluten are also sources of FODMAPs. 

In particular, all these grains contain fructans, a type of oligosaccharide that falls within the ‘O' group in the FODMAP acronym. Fructans have been recognized as a key trigger of digestive symptoms in people with sensitive guts. This overlap in gluten-containing and high-FODMAP grains is why people sometimes attribute their symptoms to gluten, which is a more common term than fructans for many people. However, in people with IBS, it's often the fructans triggering symptoms, not gluten.

Is Gluten-Free Always Low FODMAP?

No, just because something is gluten-free does not mean it is also low FODMAP. Many gluten-free products still contain high FODMAP ingredients, which can trigger digestive symptoms in sensitive individuals. Below, we'll review some of the most common high FODMAP ingredients found in gluten-free foods.

High-FODMAP fibers

Gluten-free products are often low in fiber. To counter this, manufacturers might add inulin (chicory root extract), apple fiber, fructo-oligosaccharides (FOS), oligofructose, or other high FODMAP fiber sources to products to increase their nutritional value.

High-FODMAP sweeteners

High FODMAP sweeteners such as agave syrup, honey, fructose, and polyols, such as sorbitol (E420), mannitol (E421), maltitol (E956), xylitol (E967), and isomalt (E953), are often added to enhance the flavor profile of gluten-free products.

Additionally, if dried fruit and lactose-containing ingredients are included in foods, it may make them high FODMAP. Lactose-containing dairy ingredients include:

• Whey protein concentrate

• Yogurt

• Buttermilk

• Milk

• Milk solids 

If these ingredients are listed on a food label, the food may be high FODMAP even if the sweeteners it contains are low FODMAP.

High FODMAP flours

There are several flours that are gluten-free but not low FODMAP, such as soy flour, chickpea flour, coconut flour, and almond flour (which is only low FODMAP in a very limited amount). Simply cooking with gluten-free products might not ultimately result in a low FODMAP meal. 

Can low FODMAP foods contain gluten? 

Yes, low FODMAP foods can contain gluten. Foods like sourdough bread may be low FODMAP, but because they contain gluten, they need to be avoided by people with celiac disease or wheat allergies. 

It's also important to remember that the nature and amount of FODMAP molecules present in different food ingredients is not completely understood. For example, buckwheat is a common gluten-free ingredient that is also currently listed as a low FODMAP grain. However, recent research shows that a major portion of its soluble carbohydrate content is contributed by fagopyritols, which are non-digestible, fermentable carbohydrates similar to the GOS found in pulses such as beans, peas, lentils, and chickpeas. This means they could potentially act as a trigger for IBS symptoms.

Common foods: Gluten-free vs low FODMAP 

But remember: FODMAP content can depend on serving size, preparation, and specific ingredients. Because gluten and FODMAPs are different food components, seeing "gluten-free" on a package doesn't automatically mean it's low FODMAP, and vice versa.

Which diet is right for you? 

The right diet for you depends on the condition and GI symptoms you're trying to improve. In some cases, a combination of the two diets may be necessary (for example, if you have both celiac disease and IBS), but this should always be done under the supervision of your healthcare team, including a doctor and experienced dietitian to ensure you're still getting the nutrients you need.

You may benefit from a gluten-free diet if:

If you have celiac disease or a wheat allergy, a gluten-free diet is necessary to manage symptoms and prevent complications. If you have gluten intolerance or non-celiac wheat sensitivity, a gluten-free diet may also be beneficial.

You may benefit from a low FODMAP diet if:

If you have a disorder of gut-brain interaction (DGBI) such as IBS or functional bloating, or are experiencing ongoing gas, bloating, and abdominal pain, you may benefit from a temporary low FODMAP diet. 

However, it's important to remember that you should eventually reintroduce the eliminated foods so you can determine which (if any) were triggering your symptoms. This will allow you to have as varied a diet as possible and avoid unnecessarily restricting foods. FODMAPs act as fuel for your good gut bacteria, so including them in your diet is a way to naturally support your gut microbiome and overall health.

Overall, not all gluten-free products are low FODMAP foods. Just because a product says it is gluten-free does not mean it is always safe for use while on the low FODMAP diet. Ideally, choose Monash low FODMAP-certified products that have been verified through extensive testing to contain very low levels of FODMAPs. 

If a product hasn't been tested specifically for FODMAP content, check the label for any high FODMAP ingredients. If it doesn't contain any, or if they're very far down on the ingredient list, they may be okay to consume. 

Do enzymes work for FODMAPs?

Digestive enzyme supplements can work for certain FODMAPs. For example:

• Enzymes containing fructan hydrolase break down fructans

• Enzymes containing alpha-galactosidase break down GOS

• Enzymes containing lactase break down lactose

These enzymes work by breaking FODMAPs down into simple sugars that can be quickly absorbed by the small intestine and help reduce fermentation in the large intestine. For people with a FODMAP intolerance, this can help broaden their dietary choices and enjoy a wider range of delicious, gut-friendly foods, without having to worry about digestive side effects.

Managing FODMAPs with FODZYME®

FODZYME is a digestive enzyme blend that breaks down the most common FODMAP triggers. As a powder applied directly to food, FODZYME is specifically designed to maximize contact between the enzymes and FODMAPs, which provides more active digestion time than pills or capsules. This can help you enjoy your favorite meals with confidence and give your body the nutrients it deserves.

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References

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4. Whelan K, Abrahmsohn O, David GJ, Staudacher H, Irving P, Lomer MC, Ellis PR. Fructan content of commonly consumed wheat, rye and gluten-free breads. Int J Food Sci Nutr. 2011 Aug;62(5):498-503.

5. Marín-Sanz M, Sánchez-León S, León E, Barro F. Comparative characterization of the gluten and fructan contents of breads from industrial and artisan bakeries: a study of food products in the Spanish market. Food Nutr Res. 2022 Jun 10;66.

6. Ispiryan L et al, Fundamental study on changes in the FODMAP profile of cereals, pseudo-cereals, and pulses during the malting process. Food Chemistry, Vol 343, May 2021, 128549.