Natto (Fermented Soybeans, With Sauce, Japan)
Legumes & Tofu · Legumes
The Monash app's Japan-labelled natto-with-sauce entry is low FODMAP at 45 g, approximately 2¾ tablespoons. It lists 99 g as moderate and 117 g as high. These figures describe the tested combination of fermented soybeans and sauce, rather than permission to use any sauce with any amount of natto.
Serving sizes for natto (fermented soybeans, with sauce, japan)
Natto with sauce, Japan entry: 45 g green, 99 g amber and 117 g red. The sauce is part of this preparation.
Tested serving sizes
| Serving | Amount | Main FODMAP | Rating |
|---|---|---|---|
| 2 3/4 tablespoons | 45 g | Fructans 0.05 g | |
| 6 tablespoons | 99 g | Fructans 0.1 g | |
| 7 1/3 tablespoons | 117 g | Fructans 0.3 g |
Breakdown for 2.75 tablespoons
Is natto (fermented soybeans, with sauce, japan) low FODMAP?
At 99 g, fructans are amber; at 117 g, they are red. GOS remains green at those two listed servings. Plain natto without sauce has a separate 40 g green reference. Differences between these entries cannot establish that a sauce lowers FODMAPs or that all sauce recipes are interchangeable.
Natto (Fermented Soybeans, With Sauce, Japan) and IBS: what to know
For a breakfast bowl, identify the natto-and-sauce component before considering the rice, toppings and other ingredients. The app itself advises checking ingredients for this entry. A green reference for the tested product does not rate extra sauces added at the table, and tolerance still varies from person to person.
Gut-friendly ways to eat natto (fermented soybeans, with sauce, japan)
Check that the product description and included sauce match the preparation you intend to use. Measure the combined natto-and-sauce portion before adding it to the rest of your meal. If you prefer the beans without the supplied seasoning, switch to the plain-natto reference instead of carrying the 45 g figure across automatically.
Frequently asked questions
Can I replace the included sauce with a different one?
The checked result is for natto with its tested sauce preparation. A replacement changes the mixture, so review that sauce's ingredients rather than assuming the same rating.
Why is the green weight different from plain natto?
The two entries describe different preparations. Their listed amounts alone do not isolate the effect of the sauce or prove that adding sauce reduces the beans' FODMAP content.
Is the 117 g serving still low because natto is fermented?
The 117 g serving is red in this entry. The low reference is 45 g, and the fermentation description does not override the larger portion's result.
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Sources and editorial notes
- Monash University FODMAP Diet App
Monash University FODMAP Diet app entry “Bean, soybean (Natto), fermented (with sauce)” checked directly on 27 September 2026. The portion weights, traffic-light ratings and FODMAP groups discussed here were verified in matching detail panels. Numerical FODMAP concentration estimates elsewhere in the catalogue were not validated by this check.