Soy & FODMAPs: Okay to Eat?
This is a great question and one we hear a lot. And the answer is, yes, no and depends.
We know, not a clear answer! But one thing to note is that the low FODMAP diet is not soy free! As with many attributes of the low-FODMAP diet we all have to pay attention to detail.
We are going to break it down for you, step by step so that you will be well equipped with the info you need to weed out which soy products are okay and which to avoid.
The reason why some are okay and some are not is because the maturity of the beans and/or the manufacturing process reduces the FODMAPs in soybeans and some soy products.
By the way, soy is sometimes listed as “soya” on labels. Same thing with same FODMAP implications.
Firm and Extra Firm Tofu – Soft tofu (see below) contains FODMAPs, but firm and extra firm are allowed 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.
By the way, Monash calls these “plain” and “firm” tofu, so be careful with terminology going from their Australian perspective to U.S. labeling.
Fresh or Frozen Edamame in the Pod – Edamame are young soybeans in the pod. Their immature state yields a different analyzed profile from the mature beans that are used to make soy flour or soymilk, for instance.
If you are lucky enough to have access to fresh, by all means, check them out. Otherwise, it is fairly easy to find frozen in natural food stores. Simply steam the pods and serve warm or room temperature sprinkled with coarse salt.
Monash recommends a serving of 1 cup (50 g). (Note: The Monash app shows them in the pod, but the language says “soybeans only”, so it is not clear whether their measurements are for shelled beans or in the pod). Here are our measurements: When we weighed 1/4 cup of beans it equaled 40 g. 1 cup in the pod weighed 80 g.
1/4 cup (40 g) of the actual soybeans came from 30 pods! They typically have 2 to 3 beans per pod so you can eat a lot! Relax and have a little snack.
Frozen Shelled Edamame – All the same info for this stands as in the above bullet point, however, since these come already shelled it is much easier to overdo and eat too many.
Monash serving size is 1 cup (50 g); for us, 1/4 cup weighed 40 g, so we suggest that you start with less than 1 cup to try. They are great tossed into soups or stir-fry dishes; just pay attention to serving size.
Soy Sauce – Thankfully soy sauce is Monash approved in amounts up to 2 tablespoons (42 g), which is plenty to season our food. Monash lists “soy sauce” on the app. You might come across recipes that call for “tamari” or “shoyu”.
Shoyu is another term for soy sauce, which is made from a combination of soy and wheat.
Tamari is wheat free, often labeled as gluten-free and has a slightly thicker texture and bolder flavor. While neither shoyu nor tamari is directly addressed by Monash we suggest you could try them and see how you do.
Whatever you use, make sure it is naturally brewed for best taste.
Soybean Oil – As with all oils, the carbohydrate content is nil. You can enjoy oil made from soybeans.
Soy Lecithin – You might notice this ingredient listed in packaged foods and on labels for many chocolate bars. Soy lecithin is a combination of an oil and fat and is therefore considered low FODMAP even though it hasn’t been formally tested.
As far as your chocolate bars go, it is used as an emulsifier and it is used in very small qualities.
Soy Milk Made from Soy Protein or Soy Protein Isolate (also see below) – Soymilk made from soy protein, not whole soybeans, can be tolerated. A U.S. based brand – 8th Continent – made with soy protein is available in some areas with limited availability and would be worth seeking out.
If the ingredient label says soybeans, soy beans or “made from whole soybeans”, it’s a no-go.
Soy Yogurt Made from Soy Protein or Soy Protein Isolate – If you can find soy milk yogurt made from soy protein or soy protein isolate and NOT whole soybeans, it might be worth giving a try.
Miso – This fermented soybean product is a classic Japanese condiment and can be used in sauces and soup; it is Green Light approved up to 12 g. Unfortunately Monash lists this as “2 sachets”, which means nothing to most of us.
We measured it out for you! 12 g equals about 2 American teaspoons. If you are new to Miso, we highly recommend South River brand.
Tempeh – This is made from lightly fermented soybeans that have been pressed into a cake. Make sure you read labels and look for plain tempeh; many are packaged already flavored and high FODMAP ingredients might be used.
Monash approves up to 100 g of plain tempeh, which is a piece that is 4.5-inches by 1.5-inches by 1-inch thick (11 cm by 4 cm by 2.5cm thick). Servings higher than 220 g contain high amounts of fructans and GOS.
Soy Milk Made from Whole Soybeans – Soymilk made from whole soybeans is high in FODMAPs and should be avoided. Unfortunately, all of the commercially available soymilks in the U.S. as of this writing are made from whole soybeans.
Soft Tofu – While firm and extra firm tofu are pressed firmly and therefore the FODMAP filled whey is drained away, soft tofu is not pressed and is, therefore, FODMAP rich. Soy Yogurt – Popular brands, such as Silk, are made from soymilk made from whole soybeans (label lists “Filtered Water, Soybeans”), so it is not recommended on a low FODMAP diet.
Soy Flour – This is made from grinding mature dried soybeans and is, therefore, a product that is concentrated with FODMAPs. Please note that soy flour is considered high FODMAP, and yet it is within certain products that have been lab tested and certified as low FODMAP. Serving size is very important, but in general, consider it high FODMAP.
Mature Soy Beans – Mature soybeans, either dry or fresh, are high in FODMAPs.
Soy Nuts – This is an educated assumption on our part but soy nuts are made from mature soybeans, so we bet, once they are tested, that they will be high in FODMAPs. Best to avoid for now.
Soy Products to Possibly Try
Soy Protein Powder – It is possible that some soy-based protein powders are low enough in FODMAPs to be tolerated but more testing and research has to be done.
We need to read labels (as always) and understand the difference between soy protein and soy protein isolate. Basically, soy protein is a powder made from defatted soybean meal.
During the manufacturing process the oligosaccharide content is greatly reduced (a good thing for us FODMAPers), but there can still be a good amount of fiber intact, which can be problematic.
Soy protein isolate is soy protein that has been further refined and the fiber is removed. Monash does Green Light soy milk made from soy bean protein, so why not try a soy protein powder made from either soy protein or probably even better, soy protein isolate?
No guarantees, but your body is the best judge.