Natto is sometimes called the most difficult dish of Japanese cuisine, because the intense smell of fermentation, the stringy strands and a texture that surprises on first contact mean that not everyone will like it right away. Some people try it once and put the jar back on the shelf. Others, however, don’t try it at all. Freeze-dried natto is the answer for those who would like to have this fermented product in their diet, but have been bounced by its classic form. Below, we explain how it differs from fresh natto, what it tastes like, how to prepare it and for whom it is a good choice.
The text also describes a product from our own range, freeze-dried natto BIO Natto Active. The health claims made here are based on sources in the bibliography at the end, not on our findings.
Why fresh natto doesn’t taste good to everyone
The distinctive aroma and texture of natto is no accident, but the result of the fermentation of soybeans by the bacteria Bacillus subtilis natto. During this process, aromatic compounds are produced, including pyrazines and ammonia, responsible for the distinct odor. At the same time, the bacteria produce glutamic acid polymer, the famous stringy strands that wrap around chopsticks and spoons.
For Japanese people, for whom natto has been part of their daily diet since childhood, these are familiar and desirable characteristics. In contrast, for a person who encounters natto for the first time as an adult, it can be a major sensory barrier. It’s worth simply naming it, rather than pretending it’s not there.
Freeze-drying changes this sensory experience fundamentally. By removing the water, most of the sensations troublesome to some people disappear, and the ingredients valued in fresh natto remain in the product.
What is freeze-dried natto
We are familiar with freeze-dried foods on a daily basis, although not always by that name. They are, for example, fruit in muesli and ice cream, part of instant coffees, dried travel and astronaut food. The process involves dehydrating the product under conditions that do not destroy its structure and sensitive components.
Freeze-dried natto is fermented, organic soybeans from which water has been removed in a controlled manner. In practice, it looks like small brown crisps, somewhat resembling caramelized nuts. A serving is about 20 grams, or a bag enough for two days. It weighs practically nothing and fits in a backpack pocket or desk drawer.
The moisture content of the final product is about 1 percent. This makes the product durable and does not require refrigeration, which is the norm for fresh natto.
How it is made, or freeze-drying in a nutshell
The process looks roughly like this. First, fresh natto is quickly frozen at a very low temperature, from minus 40 to minus 80 degrees Celsius. Rapid freezing is key here, because it allows fine ice crystals to form in the product, which do not damage the structure of the soybeans or degrade sensitive ingredients.
The frozen natto then goes into a vacuum chamber. Under low-pressure conditions, the ice transforms directly into steam, bypassing the liquid phase. This phenomenon is called sublimation and removes up to 95 percent of the water without classic high-temperature drying.
At the end, the product undergoes desiccation, which eliminates residual moisture. As a result, natto retains its texture, does not spoil and is resistant to the growth of mold and unwanted microorganisms.
Classic high-temperature drying would degrade some of the thermosensitive components of fermented soybeans. Freeze-drying, on the other hand, circumvents this problem because the product remains in conditions that protect them at all times. For a manufacturer that has been working for years to preserve the properties of fresh natto in a sustainable form, this technological solution makes sense. Read more about the patented method of drying fermented soybeans in a separate story.
What it tastes like and how to eat it
Freeze-dried natto tastes very different from fresh. It’s crunchy, slightly nutty, with a hint of umami and a slight sweetness from the fermented soybeans. Gone is the stringy texture, and gone is the vast majority of the characteristic odor. What remains as a result is a flavor that is much more neutral and easier for the European palate to accept.
In practice, they can be eaten in several ways:
- As an addition to natural yogurt, syr or oatmeal. It goes well with bananas, strawberries, raspberries, nuts.
- With a spoonful of soy sauce and a dash of wasabi, that is in classic Japanese style, but already without the aroma and textural barrier.
- As a stand-alone snack, straight from the bag, without preparation.
- As a sprinkle on salads, creamy soups, pasta, rice dishes.
A 20-gram serving is a viable component of a meal, not just a garnish. At the same time, it provides about 9 grams of protein, which for a small volume is comparable to more caloric protein products.
What’s left of fermented soybeans after freeze-drying
This is important for people who associate natto primarily with composition. Freeze-drying was chosen precisely because it preserves in the product everything we value in fresh natto. The difference is that here we get the same ingredients in a light, crunchy form that can be kept on hand for a long time. Below we describe each group.
Vitamin K, including the K2 form MK-7
Vitamin K in the natural diet is found in two main forms: K1 (phylloquinone, mainly in leafy vegetables) and K2 (menaquinones, MK-4 to MK-13, present in fermented foods and some animal products). Natto is one of the richest known dietary sources of the MK-7 form, with content in the region of 1,000 µg per 100 grams [8]. According to the European Food Safety Authority (EFSA), vitamin K contributes to proper blood clotting and helps maintain healthy bones [1]. These two statements are approved health claims in the European Union and refer to vitamin K as a nutrient. In addition, the MK-7 form is the subject of separate scientific studies on bone metabolism, among other topics [2, 3].
Nattokinase and live bacterial cultures
Nattokinase is an enzyme formed during fermentation of soybeans by Bacillus subtilis natto. The safety of an isolated extract from fermented soybeans standardized to nattokinase was evaluated by an EFSA panel in 2016 under the novel food procedure [4]. However, nattokinase itself has no approved health claims in the European Union. At the same time, research into its biochemical properties is ongoing in the scientific literature, including systematic reviews and meta-analyses of randomized clinical trials [5, 6]. We summarize the state of knowledge in the “What the science says and what we don’t yet know” section below.
In addition to nattokinase, live cultures of Bacillus subtilis bacteria are preserved in the product. That is why the dehydration process is carried out at low temperatures, rather than by classical drying.
Isoflavones, spermidine and PQQ
Soy isoflavones are compounds naturally present in soybeans, whose bioavailability in fermented soybeans is the subject of scientific research. We described them in detail in a post about soy isoflavones in natto.
Spermidine and PQQ (pyrroloquinolinquinone), on the other hand, are two compounds that have been appearing in scientific publications in recent years. Natto is one of their natural dietary sources. However, neither of these compounds has an approved health claim in the European Union, and their role in the diet remains the subject of further research. More in separate texts on spermidine and PQQ vitamin.
Plant protein and the nutritional value of a serving
A 20-gram serving of the product provides about 9 grams of plant protein derived from fermented soybeans. That’s a value comparable to a serving of tofu or beans, with much less volume and weight.
What science says and what we don’t yet know
In content about fermented products, it is easy to overinterpret. That’s why we try to avoid it. Below what we know for sure and what we need to investigate.
What is well documented
- Vitamin K has a documented role in the human body in blood clotting and bone metabolism. These two functions are the basis of EU-approved health claims [1].
- The MK-7 form has a longer half-life in the body than K1 and MK-4, as reported in the literature [3].
- Natto is one of the richest dietary sources of MK-7, which is confirmed by review papers on the composition of fermented soybeans [8].
What is the subject of ongoing research and should not be presented as a certainty
- The effects of nattokinase on various cardiovascular parameters are the subject of clinical trials, including meta-analyses of randomized controlled trials [5, 6]. The results are sometimes inconclusive, and the authors of the reviews point out the need for further long-term studies with larger sample sizes.
- Spermidine and PQQ are described in the scientific literature, but do not have EU-approved health claims.
- Soy isoflavones have been described in the context of diet, but their menopause-related health claims have been rejected by EFSA due to insufficient evidence.
When it’s a good idea to consult your doctor before including natto in your diet
- Taking anticoagulants (e.g., warfarin, acenocoumarol, NOACs) or antiplatelet drugs. Vitamin K affects the effect of warfarin, and nattokinase exhibits fibrinolytic activity under laboratory conditions [4, 7].
- Planned surgical procedures.
- Blood clotting disorders.
- Pregnancy and breastfeeding (EFSA excluded these groups from the target population in its 2016 opinion on nattokinase [4]).
- Soy allergy.
The content of this article is for informational purposes and is not a substitute for the advice of a doctor or nutritionist.
For whom freeze-dried natto is a good choice
Three audiences that will be particularly benefited by this form.
The first is people who wanted to incorporate natto into their diet, but bounced back from its classic form. The smell, strands and texture are real barriers. For them, the crunchy form eliminates them and opens up the product to a much wider group.
The other is for travelers, tourists and people working away from home. Fresh natto requires a refrigerator and has a limited shelf life. Freeze-dried, on the other hand, can be taken in a backpack on a trek, to work or on a long trip. It takes up as much space as a tea bag and lasts at room temperature for up to three years.
The third is for those for whom fresh natto is the first choice, but they also want to have it in a convenient backup form. When fresh just isn’t in the house, then freeze-dried acts as a backup ingredient in the pantry.
Durability and storage
Freeze-dried natto is stored at room temperature, in a dry place. It does not require refrigeration. The shelf life of the sealed package reaches about three years, provided it is protected from moisture.
After opening the bag, it is best to eat the contents within one to two days. The longer the product remains in contact with the air, the faster it loses its characteristic crunchiness, as it begins to absorb moisture. Therefore, the portion of 20 grams is deliberately selected so that it will last for two days and does not require storage of leftovers. If there is more left over, it is worth transferring the product to a tightly sealed container.
In comparison, fresh natto requires a refrigerator and has a much shorter shelf life, usually several weeks. This is one of the main practical differences between the two forms.
Will freeze-dried natto replace fresh
In short: it does not replace, but complements. These are two different forms of the same fermented product, each with its own use.
For a person who has come to love classic natto with all its sensory characteristics, the fresh version will remain the first choice. The lingering strands and intense aroma are a feature, not a drawback, for such recipients, and no other form will convey this.
For a person who reacts to the smell or texture of fresh natto with aversion, the freeze-dried form can be an entry into the world of this product. It’s a different way of serving the same fermented soybeans, preserving the ingredients and with a different sensory profile.
It’s worth having both on hand and reaching for the one that just happens to fit the situation better.
Sources and scientific basis
The content is based on publicly available positions of regulatory authorities and scientific publications indexed in PubMed and EFSA Journal databases. Links lead to original sources.
Vitamin K and MK-7 form
- EFSA, Health claims on vitamin K. Commission Regulation (EU) No. 432/2012 of May 16, 2012 establishing a list of authorized health claims on foods. Access the EU Register: EU Register on Nutrition and Health Claims. EFSA Scientific Position: Scientific Opinion on the substantiation of health claims related to vitamin K, EFSA Journal 2009.
- Knapen MHJ et al, 2013. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporosis International. PubMed: 23525894.
- Akbari S, Rasouli-Ghahroudi AA, 2018; Sato T et al, 2020. MK-7 and Its Effects on Bone Quality and Strength. Review paper indexed in PubMed Central: PMC7230802.
Nattokinase and EFSA safety assessment
- EFSA NDA Panel, 2016. safety of fermented soybean extract NSK-SD® as a novel food pursuant to Regulation (EC) No 258/97. EFSA Journal. 10.2903/j.efsa.2016.4541. The opinion concerns safety, not health efficacy.
Nattokinase in clinical trials
- Li X et al, 2023. Nattokinase Supplementation and Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Reviews in Cardiovascular Medicine, 24(8): 234. DOI: 10.31083/j.rcm2408234.
- Gallelli G et al, 2021 Data Recorded in Real Life Support the Safety of Nattokinase in Patients with Vascular Diseases. Nutrients, 13(6): 2031. PubMed: 34204609.
- Gallelli G et al, 2024. Comparative Cardioprotective Effectiveness: NOACs vs. Nattokinase, Bridging Basic Research to Clinical Findings. Biomolecules, 14(8): 956. DOI: 10.3390/biom14080956.
MK-7 content in foods
- Schurgers LJ, Vermeer C, 2000. Determination of phylloquinone and menaquinones in food: Effect of food matrix on circulating vitamin K concentrations. Haemostasis, 30(6): 298-307. DOI: 10.1159/000054147 This paper contains data on MK-7 content in natto of 998 µg per 100 g.
Freeze-dried BIO natto is produced at the Polish BIO Natto Factory in Zielona Gora, from organic soybeans and no additives. Available in our online store.
Author: Marek Kolodziejski, producer of organic natto in Poland since 2013, owner of a patent for a method of convection drying of fermented soybeans, winner of the 2024 Economic Award of the Marshal of the Lubuskie Region in the microenterprise category. Content developed in substantive cooperation with the Discare Foundation, which conducts research and development in the field of biotechnology and food technology, including fermented soybeans.
Article updated: April 2026 The content is for informational purposes and does not constitute medical advice. People taking anticoagulant or antiplatelet medications, pregnant and lactating women, and those with blood clotting disorders should consult a doctor about including natto in their diet.
