Soy Sauce
Serving sizes
Soy Sauce changes rating with portion size. Its rating is estimated from what it is made of, so the servings are described rather than weighed.
- Small serving
- Large serving
Soy sauce is Low FODMAP, a fermented seasoning used in such small splashes that its soy and wheat origins fade into the background.
- Fermentation breaks down most of the fermentable carbs in the soy and wheat, so a small serving stays low, climbing to moderate at a large serving as the wheat-derived fructans add up.
- Most soy sauces behave this way, though very salty or heavily poured uses can shift the balance, so keep an eye on how much you splash in.
A light drizzle to finish a dish keeps you comfortable, and a certified gluten-free tamari is a handy option if you want to pour more freely.
Why soy sauce is rated low
Soy sauce comes in low at a Small serving, which is the answer most people are looking for before a stir fry. No FODMAP subgroup is recorded against it, and its rating is estimated from what soy sauce is and how it gets used rather than from a measured serving, so the ladder is described in words rather than in an amount. Low is not the same as unlimited, though. The data records a second rung, and at a Large serving soy sauce moves up to moderate. Nothing between those two rungs has been tested here, so the practical reading is simple: a Small serving is the rung to stay on, and the bigger risk for most people is not the soy sauce itself but the bottled sauce it arrives inside.
What changes your risk
- Serving size The only lever the data speaks to directly. A Small serving is low and a Large serving is moderate, with nothing tested in between, so treating soy sauce as a seasoning rather than a pouring sauce keeps it on the rung the data actually rates.
- What else is in the bottle Teriyaki, hoisin, oyster sauce, black bean sauce and most jarred stir fry and marinade sauces are built on soy sauce and then list onion or garlic in the same ingredient line. Those bring FODMAPs that plain soy sauce does not, and they are usually what turns a meal rather than the soy sauce.
- Dipping versus cooking Poured into a dipping dish, soy sauce is used generously and is hard to keep track of. Stirred through a dish that serves several people, the same bottle is divided across the plates, so the amount landing on any one plate is much easier to keep at a Small serving.
- The rest of the meal Because no subgroup is recorded here, stacking with soy sauce is about the whole meal's FODMAP load rather than one shared subgroup. Soy sauce sitting low does nothing to offset noodles, a sauce base or a side that is carrying a load of its own.
What else works
For a low food the useful list is the lookalikes rather than the replacements, and the lookalikes here are the thicker bottles on the same shelf. Teriyaki, hoisin, oyster sauce, black bean sauce and jarred stir fry sauces are not soy sauce with extras, they are usually onion and garlic sauces with soy sauce in them, and they need the label read. Tamari is worth knowing about: it is generally made without wheat, which matters if gluten is also being avoided, but it follows the same ladder as ordinary soy sauce and is not a licence to pour more. For building the same savoury depth without leaning harder on the bottle, garlic infused oil, toasted sesame oil, ginger, chives, the green tops of spring onions and a pinch of asafoetida all pull their weight.
How to keep it low
Buy plain soy sauce or tamari and build sauces yourself rather than starting from a jar, since that is where onion and garlic get in. At the table, pour into a dipping dish rather than over the plate, because the amount stays visible that way and a Small serving is much easier to hold to. When a recipe calls for a marinade, measure the soy sauce into the marinade and spread it across the whole dish rather than finishing each plate with more. Eating out, ask for sauce on the side so the kitchen's pour is not the one that decides, and be aware that house stir fry sauces and dumpling dips are usually garlic based even when soy sauce is the first thing you taste.
Common questions
is soy sauce low fodmap
Yes at a Small serving, which is the rung the data rates low. A Large serving moves up to moderate.
how much soy sauce can i have on a low fodmap diet
The data for soy sauce is qualitative rather than a weight, so there is no gram or spoon figure to quote. It records a Small serving as low and a Large serving as moderate, with nothing tested between them.
is tamari better than soy sauce for fodmaps
Tamari is usually made without wheat, which matters for gluten, but it carries the same ladder here. Treat it the same way and keep it to a Small serving.
can i use soy sauce on the elimination phase
Yes, at a Small serving. The thing to watch during elimination is not the soy sauce but the teriyaki, hoisin, oyster and stir fry sauces it gets blended into, which commonly list onion and garlic.
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Informational only, not medical advice. Individual tolerance varies. Talk to a healthcare professional or a dietitian for personal guidance.
Soy Sauce is an estimated rating: it is inferred from the food's ingredients and composition and cross-checked, not measured directly in the papers below. The low, moderate and high cutoffs are still those of Varney et al. (2017).
References
- Fructan and free fructose content of common Australian vegetables and fruit. Muir et al. (2007), J. Agricultural and Food Chemistry 55(16):6619-6627.
- Measurement of short-chain carbohydrates in common Australian vegetables and fruits by HPLC. Muir et al. (2009), J. Agricultural and Food Chemistry 57(2):554-565.
- Quantification of fructans, galacto-oligosaccharides and other short-chain carbohydrates in processed grains and cereals. Biesiekierski et al. (2011), J. Human Nutrition and Dietetics 24(2):154-176.
- Dietary sorbitol and mannitol: food content and distinct absorption patterns. Yao et al. (2014), J. Human Nutrition and Dietetics 27(Suppl 2):263-275.
- FODMAPs: food composition, defining cutoff values and international application. Varney et al. (2017), J. Gastroenterology and Hepatology 32(Suppl 1):53-61. Supplies the low, moderate and high cutoffs used on this page.
Last reviewed September 22, 2026.