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⚠️ Are you taking anticoagulant medication (e.g. acenocoumarol, warfarin)? Natto is the richest natural source of vitamin K, which may reduce the effect of these drugs. Consult your doctor about your diet. See the important legal and medical information.
A traditional Japanese fermented soy product, made in Poland from certified organic (BIO) soy
Natto is a traditional Japanese fermented soy product. It is created by the action of Bacillus subtilis Natto bacteria. We have been making it in our Zielona Góra manufactory for over 10 years. We combine Japanese tradition with Polish engineering precision. Every batch is made from certified organic (BIO) soy. We worked out the fermentation parameters together with researchers from LOIiWA in Sulechów.
Natto is cooked soybeans fermented by Bacillus subtilis bacteria. The product is characterised by an intense smell, a sticky texture and the formation of distinctive, stringy threads. It is one of the richest natural sources of vitamin K2 in the MK-7 form.
Where natto comes from
The oldest documented references to natto come from Japan over a thousand years ago. The traditional recipe is simple: cooked soybeans are inoculated with Bacillus subtilis bacteria and left to ferment in warmth. After 12-24 hours the soybeans become covered with a characteristic sticky coating, and fermentation changes their structure, taste and nutritional composition.
In Japanese culture natto is traditionally eaten for breakfast, with rice, soy sauce, mustard and chopped chives. Many regional variants of the recipe exist across Japan, and some family-run workshops have continued production for several hundred years.
What natto tastes and smells like
Natto divides people. The smell is intense and earthy; some compare it to mature cheese, others to ammonia. The taste turns out to be milder than the smell suggests: nutty, slightly bitter, with a note of umami.
The texture is a topic of its own. The beans are coated with a sticky film that, when stirred, forms long, stringy threads. The longer you stir, the thicker the foam becomes and the milder the taste. The first encounter can be a challenge, but many people come round to it after a few tries.
What natto contains
Natto is a product with a complex composition. Fermentation gives the soybeans new compounds that are not present in their raw form. The main groups of components:
Vitamin K2 MK-7
Fresh natto is one of the richest natural sources of vitamin K, mainly in the form of menaquinone-7 (K2 MK-7). The content in fresh natto reaches about 1970 µg per 100 g. That is exactly how much our fresh natto from certified organic (BIO) soy contains.
Nattokinase
A proteolytic enzyme formed during the fermentation of soy by Bacillus subtilis Natto. It was discovered in 1980 by the Japanese scientist Hiroyuki Sumi.
Spermidine and PQQ
Fermented soy contains spermidine (a polyamine) and PQQ (pyrroloquinoline quinone). Both compounds occur naturally in fermented products.
Live cultures of Bacillus subtilis Natto
Fresh natto contains live cultures of fermentation bacteria. They form endospores characteristic of traditional Japanese fermentation and remain in the product until the end of its shelf life.
Plant protein
Fermented soy contains complete plant protein with all essential amino acids. Fermentation increases its bioavailability and reduces the presence of antinutrients (protease inhibitors).
Soy isoflavones
Natto contains soy isoflavones, including genistein and daidzein. Fermentation converts them into aglycone forms that are more readily absorbed than the forms found in unfermented soy.
Nutritional values (per 100 g of product)
Fresh natto from certified organic (BIO) soy. Typical values; they may vary between batches depending on fermentation conditions.
| Component | Amount per 100 g | % NRV |
|---|---|---|
| Protein | 15.0 g | 30% |
| Dietary fibre | 7.97 g | n/a |
| Calcium | 90 mg | 11% |
| Potassium | 685 mg | 34% |
| Vitamin K (K2 MK-7) | 1970 µg | 2627% |
NRV is the nutrient reference value for an adult. Values based on the typical composition of fresh natto from organic (BIO) soy.
How to eat natto
Traditional portion
A traditional Japanese portion of fresh natto is about 40-50 g (one pack). In Poland, as an addition to the diet, 10-20 g per day is most common.
Traditional way of eating
In Japan, natto is most often eaten with cooked rice, soy sauce, mustard and chopped chives. Before eating, it is recommended to stir the beans vigorously with a fork or chopsticks until the characteristic foam appears, which is traditionally regarded as the moment natto is “ready”.
Absorption of vitamin K
Vitamin K is fat-soluble. Eating natto together with some fat (e.g. olive oil, avocado, sesame) supports its absorption.
Storage
Fresh natto: in the fridge at 2-5°C. It can also be frozen; at -18°C it keeps its qualities for several months. After thawing in the fridge it is fit to eat.
Frequently asked questions about natto
What does natto taste like?
The taste is nutty, slightly bitter, with a clear umami. For many people it turns out milder than the intense smell suggests.
What does natto smell like, and why?
The smell is strong and earthy. It comes from the fermentation of soy by Bacillus subtilis Natto bacteria, which break down protein and produce aromatic compounds.
How much natto should you eat per day?
A traditional Japanese portion is about 40-50 g. In Poland, as an addition to the diet, 10-20 g per day is most common.
Is natto eaten raw?
Yes. Natto is eaten without cooking, usually with rice, soy sauce and chives. High temperature weakens the live bacterial cultures and lowers the vitamin K2 content.
Why is natto sticky and stringy?
The sticky threads are a result of fermentation. The bacteria produce a polymer (polyglutamic acid) that creates the characteristic stretchy structure.
About the author
Marek Kołodziejski, M.Sc. Eng., founder and creator of the Natto.pl manufactory, an engineer leading research and development work on the fermentation and drying of natto.
Author of the low-temperature convection drying technology that protects vitamin K2 MK-7, nattokinase and live bacterial cultures.
Winner of the Economic Award of the Marshal of the Lubuskie Region (2024, Innovative Micro-enterprise category) for research work and the production of fresh and dried natto as a functional food.
