Why gluten-free isn't always low FODMAP and vice versa! (2024)

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I have been following a (moderated) low FODMAP diet for several years now and through the years, I have heard plenty of untruthful statements that lead to misunderstandings among people who follow the diet.

One of these statements is that the low FODMAP diet would be a gluten-free diet.

The low FODMAP diet is not a gluten-free diet. If you have IBS and you follow the low FODMAP diet, it doesn’t mean you don’t tolerate gluten.

Unless you have been tested and found that you have a gluten intolerance or celiac disease. Both can occur in combination with IBS, but this is definitely not the case for everybody.

People often think that the low FODMAP diet is a gluten-free diet because the low FODMAP diet eliminates a lot of foods from your diet that also contains gluten.

Because of this confusion, I want to explain to you in this blog post what the differences are between a low FODMAP diet and a gluten-free diet.

A strict gluten-free diet

The first group of people who have to eat gluten-free are people with Celiac disease. Celiac disease is an auto-immune disease that is activated by gluten.

Eating gluten damages the lining of the small intestine and this causes permanent damage to the intestines.

Therefore it is very important for people with Celiac disease that they follow a strictly gluten-free diet.

Next to that, you also have a group of people that don’t have Celiac disease but are sensitive to gluten. This is also called non-celiac gluten sensitivity (NCGS).

People who have NCGS experience symptoms such as cramps, diarrhea or a bloated feeling when they eat gluten.

In this situation, people usually have to follow an elimination diet and remove gluten from their diet for a period of time to see if their symptoms improve.

Based on the outcome NCGS can be diagnosed and then they have to start following a gluten-free diet or a diet that is low in gluten.

The low FODMAP diet

The FODMAP diet is a diet that has been developed for people with Irritable Bowel Syndrome (IBS).

IBS is a chronic disease that causes symptoms such as bloating, flatulence, stomach aches, and often diarrhoea and/or constipation.

The low FODMAP diet was developed at Monash University in Australia. This diet has been shown to be effective for many people with IBS and helps them to control their symptoms.

In this blog, you can read all about what the FODMAP diet exactly is.

On the low FODMAP diet, many products that contain gluten have to be avoided and that is also why lots of people think the low FODMAP diet is a gluten-free diet.

FODMAPs are carbohydrates (sugars) that can be found in certain foods and are not digested well by your body.

For some people, these carbohydrates cause stomach issues and because of that they can start following the low FODMAP diet: to see if limiting these carbohydrates (FODMAPs) improves their symptoms.

The oligosaccharides are one of the four groups of FODMAPs.

Oligosaccharides can be found in two groups of foods: the first groups are pulses and legumes, such as black beans, kidney beans, and white beans. This is the so-called galactans group.

The second group consists of, amongst others, onion, garlic, wheat, and other grains such as spelt (check this blogfor more information about spelt and the low FODMAP diet), kamut, and rye. This group is called the fructans group.

Gluten is protein in grains and fructans are carbs in, amongst others, several kinds of grains.

Quite some foods that contain gluten, also contain fructans and because of that, they have to be avoided or limited during the low FODMAP diet.

Left: normal wheat buns: not gluten-free and high in the FODMAP fructans. Right: gluten-free buns that are also low FODMAP.

You are following a low FODMAP diet, not a FODMAP-free diet

Another important difference between eating gluten-free and low FODMAP is that you don’t have to completely avoid FODMAPs on the low FODMAP diet.

When you have celiac disease, you have to avoid gluten strictly because they damage your small intestine. With FODMAPs, this is not the case. You simply eat low FODMAP, not FODMAP-free.

During the low FODMAP diet, you lower the amount of FODMAPs that you eat, to get your symptoms under control.

After the elimination phase, you are going to reintroduce the different FODMAP groups to see how you react to them. If you successfully reintroduce a FODMAP group, you can bring it back into your diet.

The idea is not that you continue to eat strictly low FODMAP for the rest of your life, because many products that contain FODMAPs are good for you and feed the good bacteria in your intestine.

Therefore it is important that you go through the reintroduction phase of the diet (source: A little bit yummy).

Small amounts of fructans are often allowed

During the low FODMAP diet, small amounts of FODMAPs are allowed. Monash University has tested a lot of foods from the different FODMAP groups.

Based on the quantity of a certain FODMAP that food contains, they calculate in which amounts that food is low FODMAP.

They always look at the amount in which a product won’t cause symptoms for most people with IBS.

Soy sauce is for example low FODMAP, even though it contains wheat. Also, soba noodles, made from wheat and buckwheat are low FODMAP up to 90 grams per serving.

Next to that, the Monash app, also shows that a normal chocolate chip cookie or two butter cookies are low FODMAP because they won’t cause issues for most people.

Soba noodles and soy sauce: are not gluten-free because they both contain wheat, but are low FODMAP.

I always advise you to be careful with products that are limited low FODMAP in the elimination phase. With this I mean products that cannot be eaten in unlimited amounts because they become high in FODMAPs at a certain serving.

Such as the soba noodles that I mentioned above. In the elimination phase, you can best focus on foods that don’t contain any FODMAPs and add a maximum of one food that is limited low FODMAP per meal.

In this article about FODMAP stacking, I explain into detail how this works.

After the elimination phase, in the reintroduction phase, you can test how many fructans you can tolerate. Maybe you will find out that you can eat 2 wheat chocolate chip cookies without problems.

Or you might find out that you are really sensitive to fructans and even one chocolate chip cookie already gives you problems. The tolerance levels for different FODMAP groups can differ per person.

Gluten-free products during the low FODMAP diet

Gluten-free products are handy for fodmappers in lots of cases to use as replacements for foods that contain fructans.

A lot of gluten-free pastas are low FODMAP and there are also products, such as gluten-free pizza crusts and gluten-free cookies, that are allowed during the low FODMAP diet.

It is, however, not the case that all gluten-free products are automatically low FODMAP. Often, high FODMAP ingredients are added to gluten-free products.

Therefore we always have to pay attention to the ingredients of gluten-free products to make sure that they are also low FODMAP.

Which high FODMAP ingredients are often found in gluten-free products?

There are several flours that are gluten-free, but not low FODMAP. For example soy flour, coconut flour, lupin flour and almond flour (is only low FODMAP in a very limited amount).

For a complete list, you can check this blog post where I explain which flours are low FODMAP.

Furthermore, high FODMAP fibers are often added to gluten-free products. Such as inulin, chicory fiber, oligofructose, and fructo-oligosaccharides.

Apple fiber has been tested and was found to be low FODMAP.

Next to that, you can find juice of high FODMAP fruit- and vegetables in gluten-free products, such as apple juice, pear juice, beetroot juice, or dried fruit (i.e. dates).

Sweeteners such as agave syrup, honey, fructose, and polyols, such as sorbitol (E420), mannitol (E421), maltitol (E956), xylitol (E967), erythritol (E968) and isomalt (E953) are often added to sweeten products and these are high in FODMAPs.

How to find low FODMAP gluten-free products?

The difficult thing about the low FODMAP diet is that some of the ingredients mentioned above are low FODMAP in small amounts, such as honey, which is low FODMAP up to 1 tbsp per serving.

That makes it sometimes unclear whether you can eat a product or not because you are not sure about how much of that ingredient has been added to the product.

My first tip to deal with this is to look at products that are low FODMAP certified. These are products that have been tested on the number of FODMAPs and have been certified to be low FODMAP by Monash University.

In the Netherlands, Schär is the only easily available gluten-free brand that has low FODMAP-certified products. Other well-known brands are for example: FODY, and FODMAPPED for you.

You can find many of these products in the FODMAP app from Monash University.

In the app, they tell you exactly in which amounts these products are low FODMAP. These kind of products are the safest choice because you can be sure that they are low FODMAP.

Check the ingredient list well

For gluten-free products that are not FODMAP-certified, it is important to read the ingredients list well. If a product only contains ingredients that are low FODMAP, then it is probably ok, even though the product hasn’t been tested.

If a product contains several ingredients that are high in FODMAPs, such as inulin or lupin flour, then you can better not take it.

If a product only contains one ingredient that is high in FODMAPs in larger amounts, such as honey but is totally on the end of the ingredient list, you can give it a try.

It is probable that the amount of honey it contains is so low that it is still low FODMAP. One example of this is the Wholesome seeded loaf from Schär. The ingredients of this bread are:

maize starch,water,sour dough12%16% (rice flour, water),rice starch,cereals4,3%4,3% (millet flour 2,6%, quinoa flour 1,7%),vegetable fibre (psyllium),sugar beet syrup,rice syrup,sunflower oil,soya flakes2,1%,sunflower seeds2,1%,soya bran1,9%,linseed1,9%,thickener:hydroxypropyl methyl cellulose;millet flakes1,4%,soya protein,yeast,sea salt,honey.May contain traces of lupin.LACTOSE FREE (lactose <0.007g/100g).

This bread has honey as the last ingredient on the ingredients list, but on their website it reads:

This product has been certified to be low in FODMAPs under the Monash University Low FODMAP Certification Programme.

In this case, the amount of honey in the bread is small enough for it to still be low FODMAP.Again: I do advise you to be careful with this then you are still in the elimination phase because you don’t know yet to which FODMAP groups you react. In the first phase, you can better be extra careful.

I hope that I have given you some clarity about the differences between a gluten-free diet and the low FODMAP diet and why a low FODMAP diet isn’t a gluten-free diet.

If you have any more questions, feel free to ask them in the comments below!

This blog post was written in collaboration with Schär.

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