Is soy / tofu / soy milk low FODMAP?
Depends on the form. Firm tofu is low-FODMAP. Silken tofu is moderate. Whole-bean soy milk is high in GOS. Soy-protein-isolate milk and tempeh are low.
Firm tofu 170g; tempeh 100g; silken tofu 75g; soy milk made from whole beans 0; soy milk made from soy protein 1 cup
GOS (whole-bean forms)
Soy is one of the most confusing FODMAP categories because different soy products have wildly different FODMAP loads. Same bean, different processing, different result.
The processing scale
From low to high GOS:
- Tempeh (1 cup) — fermented; GOS broken down
- Firm tofu, drained (170g / ~6oz) — pressing removes whey containing GOS
- Silken tofu (75g) — borderline
- Edamame (1/4 cup) — moderate
- Soybeans, dried/cooked (1/2 cup) — high
- Soy milk made from whole beans — high GOS
- Soy milk made from soy protein isolate — low (Western brands often)
The soy milk gotcha
In China and most of Asia, soy milk (豆浆 / 豆漿) is made from whole soybeans — high in GOS. A standard cup will trigger most fructan/GOS-sensitive people.
In the West, brands like Bonsoy (Australia/UK) and Westsoy “Plus” (US) are made from soy protein isolate — low FODMAP. Read the label: “soybeans” = high; “soy protein” = low.
The cheap supermarket soy milk in your country is almost certainly the high-FODMAP kind unless it specifically says protein.
Tofu by texture
- ✅ Firm/extra-firm tofu, drained: 170g safe — your weekday protein
- ⚠️ Silken/soft tofu: 75g borderline — small portion in soup OK
- ⚠️ Smoked / pressed tofu (lobok / 五香豆腐干): generally safe in small portions; check ingredients for added garlic/onion
- ❌ Stinky tofu (臭豆腐): the tofu itself is fine; the dipping sauce is loaded with garlic. Skip the sauce, you’re fine.
Hidden soy
- Soy sauce: low FODMAP at standard portions (the protein/GOS doesn’t survive fermentation in significant amounts). Wheat-based variants contain wheat though — use tamari if avoiding wheat.
- Miso: 1 tsp safe (lactic fermentation); a whole bowl of miso soup uses ~2 tsp dissolved, fine.
- Soybean oil: pure oil, no GOS — unlimited.
Phase 2 testing tips
If you want to test soy specifically, use whole-bean soy milk as your GOS challenge food. 1/4 cup → 1/2 cup → 1 cup over 3 days. Most people who tolerate beans/lentils also tolerate moderate soy milk.
Source: Monash University FODMAP team. Educational content; please consult a registered dietitian for personalized guidance.
Common questions
- Is Soy / Tofu low-FODMAP?
- It depends on the portion. Soy / Tofu is low-FODMAP in small servings but turns high-FODMAP as the amount increases — portion size is what matters. Safe serving: Firm tofu 170g; tempeh 100g; silken tofu 75g; soy milk made from whole beans 0; soy milk made from soy protein 1 cup.
- What's a safe serving of Soy / Tofu?
- Firm tofu 170g; tempeh 100g; silken tofu 75g; soy milk made from whole beans 0; soy milk made from soy protein 1 cup. Going above this can push it into high-FODMAP territory and trigger symptoms in sensitive people.
- Which FODMAPs are in Soy / Tofu?
- Mainly GOS (whole-bean forms). Based on Monash University testing data. These are the carbohydrate groups that can trigger IBS symptoms when poorly absorbed.