Natto (Fermented Soybeans, Without Sauce, Japan)
Legumes & Tofu · Legumes
Natto without sauce is low FODMAP at 40 g, about 2½ tablespoons, in the Japan-labelled Monash entry. The listed 92 g portion is moderate and 109 g is high. This result applies to the fermented soybeans without their sauce, rather than every natto meal or seasoned product.
Serving sizes for natto (fermented soybeans, without sauce, japan)
Japan entry, without sauce: 40 g low, 92 g moderate, 109 g high. Match the unsauced product before applying these amounts.
Tested serving sizes
| Serving | Amount | Main FODMAP | Rating |
|---|---|---|---|
| 2 1/2 tablespoons | 40 g | Fructans 0.04 g | |
| 5 1/2 tablespoons | 92 g | Fructans 0.1 g | |
| 1/2 cup | 109 g | Fructans 0.3 g |
Breakdown for 2.5 tablespoons
Is natto (fermented soybeans, without sauce, japan) low FODMAP?
Fructans are amber at 92 g and red at 109 g; GOS stays green at both of these portions. The fermented preparation has its own test result, so the rating for ordinary boiled soybeans does not describe it. Natto with sauce is listed separately at 45 g low, which does not mean that adding any sauce improves the plain beans' rating.
Natto (Fermented Soybeans, Without Sauce, Japan) and IBS: what to know
A natto package may come with a separate sachet, making it easy to overlook the difference between the beans and the finished serving. If you are tracking a meal, record whether you included the sachet or added other seasonings. Your response to the complete meal can differ from the app's plain-natto reference.
Gut-friendly ways to eat natto (fermented soybeans, without sauce, japan)
Weigh the natto separately before spooning it onto rice or another base. Keep an unopened sauce sachet aside if you intend to follow the without-sauce entry, and check the ingredients of any seasoning you add. Use the package's storage and preparation directions; the FODMAP figures do not replace those instructions.
Frequently asked questions
Does the 40 g amount include the sauce sachet?
The app entry is explicitly without sauce. A serving mixed with its sauce belongs to a different preparation, so keep those weights and entries separate.
Does fermentation make natto low FODMAP at every portion?
No. Although 40 g is green, the checked plain-natto entry becomes moderate at 92 g and high at 109 g. Fermentation does not remove the need to consider the amount eaten.
Can I use this rating for all brands of natto?
Treat the app entry as a reference for the named preparation. Check the current product's ingredients and any product-specific testing, especially when flavourings or additional ingredients are included.
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Sources and editorial notes
- Monash University FODMAP Diet App
Monash University FODMAP Diet app entry “Bean, soybean (Natto), fermented (without 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.