Did you know that the low FODMAP diet is not soy-free? That is true, but there are both low FODMAP and high FODMAP soy products. How can you tell what is what? This article discusses soy products in relation to the low FODMAP diet.
Is Soy Healthy?
I used to eat a lot of soy. Soymilk in my tea morning and midday. Soymilk with my cereal. Tofu a few times per week. Soy sauce frequently used as a condiment. Edamame as a snack of choice (love popping the beans out of the pod) or used in dishes like stir-fries and soy based succotash. Soy nuts as a snack. Soy flour as a gluten-free alternative; drinking soy based protein drinks after workouts…I could go on and on. And I thought I was eating in a positive way for me!
For many this might have been the case, but for someone who is sensitive to FODMAPS (fructans in particular), many of these choices were not good inclusions, particularly stacked on top of one another. I was overdoing soy, actually contributing to my digestive upset, and had no idea that soy was an issue.
Then I discovered the low FODMAP diet and learned that some soy was okay and some was decidedly not. It was confusing at first until I understood why.
If you are new to the low FODMAP diet be sure to read all of our articles in our Low FODMAP Diet Basics Collection so you have a good understanding of what is to follow.
Which Soy Products Are Low FODMAP?
Here’s the deal: soybeans, as in the whole bean – and especially when dry and mature – contain fructans and GOS, which are FODMAPs that we want to avoid during the Elimination Phase of the diet until we go through the Challenge Phase and know whether we are sensitive to these particular FODMAPs or not.
There are exceptions, such as immature soybeans aka edamame (see below), firm tofu and soy sauce. There are also some variables, such as those that are very serving size dependent, like soymilk made from hulled soybeans.
Related Articles: Soy Products: Low FODMAP or Not? and Are Soy Sauce and Tamari Low FODMAP?
Soy Products That Have Low FODMAP Serving Sizes
Here is a list of soy products that have low FODMAP serving sizes. Use your Monash University and FODMAP Friendly smartphone apps to get the details on specific serving sizes. These apps are musts for following the diet; they are the two primary entities that are lab testing foods and providing the results.
You can learn how to use the apps in these articles:
- How To Use The Monash University Low FODMAP Diet App
- How To Use The FODMAP Friendly Low FODMAP Diet App
Interesting Soy Facts
- Soy sauce has been lab tested by both Monash and FODMAP Friendly. FODMAP Friendly lab testing shows no FODMAP content at all, and the directions are, “Enjoy in unlimited amounts; Eat freely.”
- Ditto for tempeh: FODMAP Friendly has lab tested plain, cooked tempeh and they found no FODMAPs. “Enjoy in unlimited amounts; eat freely.”
- (Note that Monash has different lab tested results, which are explained in this article: When Low FODMAP Lab Test Results Differ. Again, please reference both apps for more info).
- Firm and extra firm have generous low FODMAP servings as enough of the whey is drained away as the curds are pressed into the firm cakes; it is the liquid whey where most of the FODMAPs reside. Silken tofu has a very small low FODMAP serving size, as less whey is removed.
- Edamame are young soybeans in the pod. Their immature state yields a different FODMAP profile than the mature beans that are used to make soy flour, for instance.
- During the fermentation process that creates miso, the proteins in the soybeans break down into peptides and amino acids, such as glutamic acid. The result is a certain kind of meaty and robust flavor that we know as umami.
- Note that soy lecithin has not been formally lab tested by Monash University but as it is a fat and does not contain any carbohydrates, it is believed to be low FODMAP.
You may want to read: How Fermentation Affects the FODMAP Content in Soy Foods and Cabbage
Soy Products With High FODMAP Content
The following soy products have been lab tested and have high FODMAP content. Best to avoid during Elimination, but feel free to try them once you are done with your Challenge Phase.
- Cooked whole soy beans, starting from dried beans
- Soy yogurt made from whole soybeans
- Soy flour
- Soy nuts
- TSP (textured soy vegetable protein)
Frequently Asked Questions
Edamame are young, green soybeans that are eaten at this level of maturity. Even if they have been frozen and then steamed or boiled, they are still “young” soybeans. Dried soybeans are mature and have a higher FODMAP content, hence the differing designations.
Tofu is made from curdling fresh soymilk with a variety of coagulants, such as nigari (derived from seawater), and then pressing the curds in a press, similarly to how cheese is made.
The FODMAPs in soybeans are GOS and fructans and they are water soluble, so the more the tofu is pressed and condensed, the firmer it becomes and fewer FODMAPs remain.
Monash University says that “Firm, drained” tofu is low FODMAP in 170 g servings.
Soft and silken tofu is coagulated but not drained, so the FODMAP content remains higher. Avoid during your Elimination Phase, unless in the very small suggested amounts. Perhaps you will be able to add it back into your diet if GOS and fructans are not your triggers.
All of these traditional foods involve some level of fermentation. During the fermentation process FODMAPs are reduced, yielding a low-FODMAP food. Tempeh is inoculated with a mold typically derived from Rhizopus oligosporus or Rhizopus oryzae; koji, a type of mold made from Aspergillus oryzae, is used to make miso and soy sauce.
All of these fermented products can be enjoyed even during the Elimination Phase in the servings recommended by Monash University.
Yes, they are. Typically in America, you will see the term “soy” on a label, while in other areas of the world you will see the term “soya”.
Yogurt made from soy milk will have the same issues as soymilk itself; look for products made from soy protein isolate and not whole soybeans. That said, it is not a given as these products have not been tested. Sample some and see how you feel.
Soy based protein powders are of interest as many people are looking for a protein powder to accompany their workouts and are simultaneously on the low FODMAP diet. These folks have to become serious label readers to determine which brands and ingredients are appropriate.
Look for the term soy protein “isolate”. This literally refers to the fact that the protein has been isolated and that the product is nearly 90% protein. Soybeans are hulled, flaked and defatted and then milled into a fine flour.
Fiber is reduced during the process as well creating a product that we can eat during the Elimination Phase and beyond. Watch protein powder labels for other FODMAPs though, like inulin for instance.
We have an entire article you may want to read: All About Low FODMAP Meal Replacements, Protein Powders & Protein Shakes
Low FODMAP Recipes To Enjoy Featuring Soy
There are so many ways to enjoy soy, even during your Elimination Phase of the low FODMAP diet. Here are just some of our recipes that include soy:
- Two Mushroom Miso Soup
- Char Siu
- And so many more!
The Takeaway
Stick with our list of low and high FODMAP soy products and you will be on your way to a successful Elimination Phase. Stick with the Monash University app and FODMAP Friendly app, check for updates, and follow the science.
The low FODMAP diet is not a soy free diet, so you will be able to continue to enjoy many soy-based products.
How about natto a kind of fermented soybeans that is slimy but very healthy especially for those with osteoporosis!
Jan, we are well familiar with natto from a culinary perspective, but it has not been lab-tested for FODMAPs. The best suggestion is to try small amounts top assess your own tolerance during your Challenge Phase. How YOU respond is the most important thing.
What a about medium firm tofu. You talk about Firm and Extra Firm and Soft but didn’t mention medium. Also what about some of the processed food products for vegans that contain soy isolate such as Yves Gluten Free burgers. And not soy but would also like to know if the Beyond Meat products are low fodmaps.
Anne, thank you for wiring. In the US the tofu that has been tested low FODMAP is called Firm and Extra Firm. In Australia Monash calls their equivalents Plain and Firm. No one has tested and reported on Medium. I personally would not use it as it has been pressed less, and therefore would contain more FODMAPs. When it comes to soy isolate, our Monash trained RDs suggest that when the ingredient listed says “soy protein isolate”, then that would be a good bet. Without the word “isolate”, no one knows if the product has not been lab tested, but it would not be recommended. Here are some recent notes compiled between me and one of our RDs in terms of the Beyond Burger: “Pea protein isolate is low. Protein content is 20 grams for this burger, suspect the pea protein falls within the safe serve. Looks like the ingredients changed a bit. I think the natural flavors need to be confirmed. They were < 2% in the past, they are now present higher on ingredient list. Not sure about the apple extract. I think it would be worth trying if natural flavors do not contain garlic or onion."So, you need to check AND also be aware that Monash rolled back their statements about pea protein and are now NOT recommending it unless it has been lab tested (the brand or item specifically).