Just like spelt, soy products cause quite some confusion on the low FODMAP diet. The question “Is soy low FODMAP?” cannot be answered with just “yes” or “no” easily. The answer actually is “it depends”. Some soy products are low FODMAP, while others aren’t. In this blog, I am going to explain to you which soy products are safe to use on the low FODMAP diet. 

Soy beans, of which soy products are made, contain high amounts of galactans and fructans and are therefore not low FODMAP. You would expect that all soy products made of soy beans are also high in FODMAPs then, but that is not the case. When soy beans are processed to make a certain soy product the FODMAP content in the soy product can become lower and therefore some soy products are low FODMAP and others aren’t. 

Low FODMAP soy products

The products below are low FODMAP and can be used during the low FODMAP diet, in the serving sizes mentioned. 

• Soy sauce – Soy sauce is low FODMAP up to 42 gram per serving, 2 tablespoons. Tamari, gluten-free soy sauce, has not been tested, but because soy sauce is low FODMAP, tamari probably is too.
• Ketjap – Ketjap is sweet soy sauce and is low FODMAP up to 20 gram per serving, 1 tablespoon. 
• Miso paste – Miso paste is often used in the Japanese cuisine, for example for making miso soup. Miso paste is low FODMAP up to 12 gram per serving, 2 tablespoons. Make sure no other high FODMAP ingredients have been added. 
• Tofu – Tofu is made of soy beans, but because of the processing of the soy beans to make them into tofu, the amount of FODMAPs in the tofu is lowered and that’s why tofu is low FODMAP. Make sure that you use “firm” tofu and no “soft” or “silken” tofu because the latter is high in FODMAPs. 
• Tempeh – Tempeh is made of fermented soy beans. The fermentation process lowers the amount of FODMAPs in the soy beans and therefore tempeh is low FODMAP. Large servings of tempeh of 220 gram or more are high in FODMAPs. A serving of 100 or 150 gram can be eaten safely. 
• Edamame beans – Edamame beans are young immature soy beans and these are low FODMAP up to 90 gram per serving. At 210 gram they contain a high amount of fructans and are no longer low in FODMAPs. 
• Soybean oil – Foods that only contain fats don’t contain any FODMAPs because FODMAPs are carbohydrates. Therefore soybean oil is low FODMAP. 
• Soy lecithin – Soy lecithin is often added to processed foods. You can find it in the ingredient list of many chocolate bars for example. Soy lecithin is a combination of fat and oil and is therefore low FODMAP.
• Soy milk made from soy protein – Soy milk made from soy protein is low FODMAP in a serving of 250 ml. Unfortunately, the most common soy milks are made from whole or hulled soy beans and therefore soy milk made from soy protein is hard to find. At least here in the Netherlands, I never managed to find it. 
• Cheese made from soy – These are often vegan cheese variations. The Monash app says that soy cheese is low FODMAP up to 40 gram per serving. Make sure to check that no other ingredients have been added to the cheese that are high in FODMAPs.

These soy products are not low FODMAP

• Silken tofu – As mentioned above, “firm” tofu is low FODMAP, but silken tofu is not. 
• Soy beans – Edamame beans are immature unripe soybeans and these are low FODMAP. Mature soybeans (you often find these canned or dried) are not low FODMAP and contain high amounts of galactans and fructans. 
• Soy milk made from soy beans – Soy milk made from soy beans is higher in FODMAPs than soy milk made from soy protein. The Monash app says that soy milk made from hulled soy beans is low FODMAP up to 60 ml per serving and soy milk made from whole soy beans is low FODMAP up to 30 ml per serving. For soy milk, I advise to avoid it during the elimination phase and reintroduction phase. If you have finished the reintroduction phase and know how you react to galactans and fructans, you can test soy milk and see how you react to it. 

These were the soy products that are listed in the Monash University low FODMAP app. Below I will go a bit deeper into a few soy products that are a bit more difficult to give a high or low FODMAP label: soy flour, soy yoghurt and soy protein powder. 

Is soy flour low FODMAP? 

Soy flour is often used in gluten-free products. Soy flour has not been tested by by Monash University yet, but it has been tested by FODMAP Friendly (another organisation that tests products on their FODMAP content). They have tested an amount 0f 50 gram of soy flour and this turned out to be high in FODMAPs. 

We do also have a reason to believe that soy flour is low in FODMAPs in smaller amounts. There are several products that have been low FODMAP certified, such as the gluten-free digestive cookies from Schär, that contain soy flour. Therefore, soy flour is probably low FODMAP in very small amounts. 

When soy flour is in a gluten-free product and it is not too far in the front of the ingredient list (the more in the front an ingredient is, the more the product contains of it) and the product doesn’t contain any other ingredients that are high in FODMAPs, it is probably safe to eat. If a product contains a lot of soy flour, you can better avoid it. 

Is soy yoghurt low FODMAP? 

Soy yoghurt has not been tested by Monash University. Just as with milk, the amount of FODMAPs in soy yoghurt can differ per brand and per product. Some soy yoghurt is made of whole soy beans and other kinds are made of hulled soy beans. Without testing it is hard to say how high the amount of FODMAPs in a certain kind of soy yoghurt is.

Because soy milk made of hulled soy beans is lower in FODMAPs than soy milk made of whole soy beans, the same probably counts for soy yoghurt. 

The advice for soy yoghurt is the same as for soy milk: try to avoid it during the elimination and reintroduction phase and test it afterwards. There are people who react very well to soy yoghurt and there are people who don’t. It is really necessary to test it for yourself to find out. 

I often hear from fodmappers that their dietician advised them to start using soy “dairy” products, such as soy milk, soy yoghurt and soy desserts. As you have read above, these products are not or very limited low FODMAP. Therefore my advice would be to be very careful with them and only use the soy products that are low FODMAP. 

Instead of soy yoghurt, you can use lactose-free yoghurt or coconut yoghurt (max. 1/2 cup). Instead of soy milk, you can use other low FODMAP milks, such as lactose-free milk, almond milk (max. 1 cup) or rice milk (max. 1 cup).

What about soy protein powder?

As soy milk made from soy protein is low FODMAP, I sometimes hear the question whether soy protein powder is low FODMAP too. Soy protein powder or soy protein isolate has not been tested by Monash University yet, but it might be possible that it is low FODMAP. Again, this depends on the processing of the soy.

In order to find out if you can tolerate soy protein powder, you will have to test it. Again, the advise is to do this after the elimination and reintroduction phase. Make sure to read the ingredient list of the soy protein powder well because often sneaky FODMAPs, such as fructose, have been added. If that is the case, the soy protein powder is not low FODMAP for sure. 

I hope that I have been able to answer the question “Is soy low FODMAP?” in this blog. If you have any more questions about soy, feel free to ask them below and I will try to help you.

Sources used for this article:

• Monash University FODMAP diet app
• FODMAP friendly – Is soy flour low FODMAP

Other blogs about the FODMAPs in foods

Would you like to read more about whether certain foods are low FODMAP and in what quantities? Check out the articles below:

Fruits and vegetables

• Are tomatoes low FODMAP?
• Is coconut low FODMAP?
• Are bananas low FODMAP?
• Are mushrooms low FODMAP?
• Is broccoli low FODMAP?
• Is kale low FODMAP?
• Is spinach low FODMAP?
• Is corn low FODMAP?
• Is avocado low FODMAP?
• Is sweet potato low FODMAP?

Dairy and grains

• Is rice low FODMAP?
• Is quinoa low FODMAP?
• Are oats low FODMAP?
• Which milk is low FODMAP?
• What cheeses are low FODMAP?
• Is butter low FODMAP?

Other foods and drinks

• What nuts are low FODMAP?
• What beans are low FODMAP?
• Is peanut butter low FODMAP?
• Is popcorn low FODMAP?
• What alcoholic drinks are low FODMAP?
• Is coffee low FODMAP?