Soy foods can be an important source of protein and other nutrients for vegetarians and vegans and a way to break away from the routine of eating animal protein for everyone else. Even Monash University recently recognized the importance of eating less animal protein by starting a Meat Free Week campaign on Instagram and posting one vegetarian a recipe a day for a week on their blog.
Soy beans are indeed a source of FODMAPs - mostly galacto-oligosaccharides (GOS) and some fructans - and not allowed during the elimination phase. Soy milk that is made from soy beans (and soy yogurt, which is made from soy milk) is also high in FODMAPs, as it is made by grinding the beans and water together. Incidentally, there is a type of soy milk made from soy protein which is low in FODMAPs. It is popular in Australia but here in the US it is not as easy to find. The only brand I came across is 8th Continent but all their varieties are high in sugar and one of them also contains inulin.
Many of the products made from soy beans, however, become low FODMAP because of what happens during the food processing. As I described in a recent blog article, it turns out that the FODMAPs in soy are soluble in water. Hence, any technique that involves soaking the soybeans in water and straining them will allow the FODMAPs to leach into the water and considerably lower the FODMAP content of that food. This is the case with firm tofu. On the other hand, silken tofu is not drained and retains all the water and the FODMAPs.
Another food processing technique that lowers FODMAP content is fermentation. This explains why plain tempeh (made from fermenting soy beans) is low in FODMAPs. Some varieties also have grains like rice or millet but most are free of wheat/gluten. Watch out for added high FODMAP ingredients like garlic, onions, or celery. See my Indonesian Tempeh Randang recipe for a tasty way to eat this less-known and appreciated soy food.
A second consideration when choosing soy products is that GOS and fructans are fibers, and the foods that are lower in fiber are also lower in FODMAPs. Immature soybeans (edamame) are an example. Monash University tested them and found them suitable in small amounts.
Soy burgers or meat substitutes have not been tested but most likely are high in FODMAPs as they may contain the fibers from soybeans. Textured soy protein, the main ingredient in many soy-based meat substitutes is high in FODMAPs. Soy protein powder may be low in FODMAPs depending on how it is processed. It is best to avoid it during the elimination phase as its FODMAP status is unknown.
Soy lecithin and soybean oil are not a source of FODMAPs and are ok. Soy sauce has been tested and found to be low in FODMAPs.
In summary, use this guide to navigate the soy aisle and don’t be afraid in experimenting with soy foods.
SUITABLE FOR A LOW FODMAP DIET
Tofu (firm or extra firm)
Plain Tempeh (no extra high FODMAP ingredients)
NOT SUITABLE FOR A LOW FODMAP DIET
Soy milk (made from soy beans)
Soy burgers/meat substitutes
Textured soy protein
Soy protein powder
Check out the Monash University App for appropriate serving sizes.
If, after completing the re-challenge phase, you find that you can tolerate GOS and fructans, you can experiment with the high FODMAP soy foods.
2 inch- stalk of lemongrass (from the bottom white part), roughly chopped
2-inch piece of ginger, peeled, roughly chopped
2 tbsp water
1 tbsp sunflower seed or canola oil
8 ounces/225 g tempeh, cut into ½-inch pieces
½ lb. small red potatoes, scrubbed and cut into ½-inch cubes
¾ tsp ground fennel seed
½ tsp ground cardamom
¼ tsp ground cloves
½ cinnamon stick (about 2 inches)
1 small can (5.46 oz/160 ml) unsweetened coconut milk
½ cup water
½ tsp salt
A few grinds of black pepper
1. Blend the lemongrass stalk and ginger with 1 tablespoon of the water. Scrape the sides of the blender, add the additional tbsp of water and blend until you have a paste (it will be a rough paste, due to the fiber in the lemongrass, but that’s ok).
2. In a nonstick skillet, heat the oil over medium high heat and sauté the tempeh until browned, about 3-5 minutes per side. Add the dry spices, cinnamon stick, the lemongrass-ginger paste and a little water, and sauté for 2 more minutes. Add the potato, coconut milk and water. Bring to a boil, lower the heat, cover, and simmer until the potato is tender, about 5 minutes, stirring occasionally.
3. Remove from the heat, season with the salt and pepper, and serve over red or brown rice.
Store in an airtight container in the refrigerator for up to 4 days.
Antonella Dewell, Registered Dietitian Nutritionist and Natural Chef