Originally published March 23, 2023. Fully updated March 28, 2026, with new fermentation technique, audio narration, and summary infographics. The health information has been reviewed for continued accuracy.
🎧 ▶️ Press the play button below to listen in English.
🎧 ▶️ 请按下面的播放按钮收听英文音频。
Introduction
This article discusses how I made my first batch of natto. I figured that with all the health benefits I learned about natto and nattokinase, I would be crazy not to take it. I don’t know any store or restaurant that sells it around my area, so I decided to make my own.
It was easy, and my first batch met my expectations. I will also include some tasting notes here and the other surprising effects of the bacteria responsible for the fermentation, Bacillus subtilis, on the human gut and the environment.
Natto is a traditional Japanese food made from fermented soybeans. Nattokinase is the enzyme extracted from it that has tons of health benefits.
- Insulin Resistance and Atherosclerosis and the Nattokinase Solution
- Protective Effects of Nattokinase against Strokes
- How to dose Nattokinase, Bromelain, and NAC
- High-Dose Nattokinase to Shrink Atherosclerosis and Lower Blood Lipids
- Nattokinase is Nontoxic with a High Safety Margin
- The Outstanding Vascular Effects and Dose of Nattokinase
- Another Study shows Nattokinase can Destroy the S1 Spike Protein
- Nattokinase Degrades the SARS-CoV-2 Spike Protein
There is a misconception that soy foods can increase breast cancer risk. That is not true. Many studies have proven that – Soy Foods Do Not Increase Breast Cancer Risk.
What you need for natto making
I used the following. Products in orange contain Amazon affiliate links, and I earn a few cents if you buy them.
- Laurasoybeans.com sells non-genetically modified (non-GMO) soybeans for natto and sprout making. Their soybeans are harvested from Iowa, and the US is the source of soybeans in Japan.
- Takahashi Natto Starter Spores (Nattomoto) – 3g (enough to make 30 kg of natto) – The instructions in the box are in Japanese. English instructions are at this link.
- Simple Deluxe 150W Ceramic Heat Emitter Reptile Heat Lamp Bulb
- You will need a bulb holder. I got one with a clamp like this. Make sure that the bulb holder can handle 150 watts.
- Or a combination of ceramic heater and lamp holder
- Inkbird ITC-308 Digital Temperature Controller 2-Stage Outlet Thermostat – the ceramic heater provides the heat, and the thermostat controls the environment inside the oven. The instructions are easy to follow. Ensure you press the button for three seconds after you make changes, or else it will not register.
- Canning Funnels for Kitchen Use, Food Grade Silicone – for storing in canning jars once you are done.
- Cling wrap is placed over the fermenting soybeans.
- Silicone Large Square Ice Cube Maker – I use this as a modification of the technique instead of a Pyrex pan
I reproduced the instructions here from Takahashi Nattomotto
Ingredients:
Soybeans 1kg, Sterilized water 10ml,
One spoon of Nattomoto powder (0.1g) – A special spoon is in the box.
- Wash the soybeans and soak them for 9 hours (Summer) to 12 hours (Winter). The amount of water should be four times as much as the beans by weight. I started with 165 gm of beans and 660 ml of water
2. Drain and boil the soybeans for 9 hours on the stove (or use a pressure cooker) till the soybeans are soft. I used an electric pressure cooker on “high” for 40 minutes. Put an inch of water inside the pressure cooker. I steamed the beans rather than boiled them. I put a folding stainless steel strainer inside the pressure cooker. You will know the beans are done if they are easy to crush with your fingers. If you use the pressure cooker, please follow the directions.
3. While the pressure cooker is cooling down, I boil water for sterilization. The amount should be enough to cover the bottom of the pan and the other utensils, like two spoons, a Stainless Steel Slotted Spoon, and a small bowl where you will dissolve the starter. Sterilization is needed because the beans will be in an environment conducive to bacterial growth. You don’t want any other germs there.
4. Transfer the beans to the pan. Use three tablespoons of the water where the beans were boiled and put them on the pan for moisture.
5. Dissolve one spoon of Nattomoto spores (0.1g) in the sterilized water 10ml. This will activate the Bacillus spores, allowing fermentation to begin. The box contains a small spoon wrapped in paper.
6. Put Nattomoto solution on the beans and stir them up carefully with a sterilized spoon. (Beans are still warm.)
7. Put the beans in a pan. Do not put many beans in one container. Three layers in each container at the most. If you drop beans on the table, DO NOT put them in the container. Every process has to be clean.
8. Put a sterilized cloth on the container and put on a lid. I used the technique of Natto Dad on YouTube. I put cling wrap at the surface of the beans and poked them many times with a toothpick. Another layer of cling wrap is placed on top of the pan and poked again with the toothpick. This technique retains moisture and temperature inside the container.
Addendum March 28, 2026, for step number 7. – Instead of a Pyrex pan, I put the soybeans with the culture in the Silicone Ice Cube Trays, then put them in an oven where the ceramic heater is.
The 2-inch by 2-inch by 2-inch ice cube holds approximately 50 g of natto, the same serving size as the store-bought natto. It also contains 2,000 FU.
The ceramic heater is controlled by the Inkbird. This modification omits the use of cling wrap on the Pyrex pan. Also, you will not need to transfer the natto end-product to an ice tray before putting it in the freezer.
I developed this modification since I make natto in large batches, such as 4 – 5 cups of raw soybeans, so that I can maximize the heat and save on electricity and time.
Another reason the cling wrap or the silicone tray lid is needed is to keep the ammonia produced by the Bacillus inside. Ammonia prevents other bacteria from growing. It also prevents soybeans from drying out, which prevents Bacillus growth. The holes in the cling wrap will allow oxygen, which the Bacillus needs to survive, to enter.
If you use the silicone lid, you don’t have to poke holes in it.
- I preheat the oven to 100F degrees (38 °C) while waiting for the water to boil. I connected the ceramic heater to the thermostat controller. Make sure to push the “on” button on the bulb holder, or the heater will not turn on. The controller stays outside the oven.
Place the container in a 100F(38 °C) to 103F(40 °C) oven or warmer. Let the natto ferment for 22 to 24 hours.
Remove from the oven (or the warmer), remove the lid (keep the cloth in place), and refrigerate for 1 night. Then, natto is done.
- The thing is, I don’t think you want to consume all that natto in one go. You can keep them in the refrigerator for about 2-3 days max, or put them in the freezer.
- What I used to do was put them in regular ice trays, but later had the idea to put them in silicone ice cube trays that can withstand the oven temperature.
Caution!!
A. Every Process and all cooking instruments have to be sterilized. I put boiled water on a prewarmed Pyrex and poured it slowly to prevent thermal shock and shattering the glass. Read How to Make Sure Your Pyrex Doesn’t Shatter
B. You can make sterilized water at home. Boil the water for 5-10 minutes, cool down and use it for the process.
Natto Taste
After 22 hours, the natto was done. I was expecting an ammonia smell but did not notice it. It has a faint smell of roasted coffee and chocolate. It is nutty and has a soft cheese taste and texture.
The feel in the mouth is like boiled okra. Mixing it in a bowl with a chopstick will make the strands thicker the more you stir. The Japanese call it neba-neba, a term for slimy foods considered healthy.
The slime contains the spores of Bacillus Subtilis. The spore form allows the Bacillus to survive extreme conditions or when food is scarce. I will tell you later in this article why that is good.
I put the freshly made natto on steamed rice and added soy sauce, chopped green onions, and onions. I had seconds. It’s that good. I will eat them every day.
I guess perspective helped me accept the sliminess easier. Knowing that natto has nattokinase that lowers blood pressure, sugar, and triglycerides and decreases atherosclerosis helped.
Natto also contains high amounts of vitamin K2, which removes the calcium from atherosclerosis to deposit in the bones and teeth.
Plus, I like eating boiled okra.
How natto prevents glucose spikes
Eating the natto with rice gave me a new understanding of how it prevents Post-Prandial Hyperglycemia (PPG) or glucose spikes.
Glucose spikes can injure the lining of the arteries and initiate or worsen atherosclerosis. I noticed that the gooey stuff mixes with the rice too. The slippery beans and rice are quite easy to swallow even when whole.
That makes the digestion of the beans slower, and the release of simple sugars like glucose becomes longer and prevents a sudden increase in blood glucose and insulin levels.
Taniguchi-Fukatsu et al. observed lower glucose after eating viscose foods like natto. Maybe my observation could help explain their results.
Bacillus subtilis: a great microbiome.
The short video, Natto, the power of Life, showed how B subtilis outgrew another bacteria E. Coli. B subtilis also has enzymes that can degrade Reactive Oxygen Species like hydrogen peroxide in the intestines, allowing the other good bacteria to proliferate.
A study published in Beneficial Microbes showed a decrease in pro-inflammatory bacteria and an increase in anti-inflammatory bacteria in healthy children with a Bacillus Subtilis DE111 probiotic supplement.
A study from Thailand showed that Bacillus subtilis probiotic supplementation eliminated more than 95% of the total S aureus colonizing the human body without
altering the microbiota.
That is relevant when Methicillin-Resistant Staphylococcus (MRSA) skin infections abound. MRSA infections are difficult to treat and have a tendency to recur.
How much natto is needed to get the health effects?
According to the Japan Nattokinase Association, a 50 gm pack of commercial nattokinase contains 2,000 FU. FU is Fibrin Degradation Units, and it indicates nattokinase activity level.
Kurosawa et al. found that with a single dose of oral NK at 2000 FU, evidence of clot dissolution, like fibrin degradation products and d-dimer.
Cobos et al. showed that 2,000 FU lowered fasting insulin and glucose levels and the HOMA index. Homeostatic Insulin Assessment (HOMA) quantifies insulin resistance and the function of the pancreatic beta-cells that secrete insulin.
Bacillus subtilis is good for plants
Cleaning up utensils that came into contact with natto may be a new experience for some because of the slime. That slime contains Bacillus spores, which are suitable for plants.
In a review in the Saudi Journal of Biological Science, the Bacillus species are a significant group of Plant Growth Promoting Rhizobacteria that could benefit plants and perform the same roles as chemical fertilizers and pesticides, acting as a biofertilizer and a biopesticide.
In an article in Gardener’s Path by Helga George, Ph.D., she said,
Bacillus subtilis can act directly against other microbes by producing a variety of antibiotics that affect fungi or bacteria. They can also act indirectly by stimulating the plant to activate its own defense mechanisms, so it can fend off attacking microbes.
This combination of activities results in a powerful biocontrol agent that is sold commercially to inhibit a number of pathogens on many different crops.
That knowledge made me use the water I used to rinse the kitchen utensils and pour it into my garden.
Natto can be used in many dishes. Iron Chef Japan has two episodes on natto. One with Iron Chef with Rokusaburo Michiba and another with Masaharu Morimoto. You can get a lot of ideas from them.
There are other ways to make natto, like in an Instant Pot or a yogurt maker. I watched and learned from Natto Dad.
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About Dr. Jesse Santiano, MD
Dr. Santiano is a retired internist and emergency physician with extensive clinical experience in metabolic health, cardiovascular prevention, and lifestyle medicine. He reviews all medical content on this site to ensure accuracy, clarity, and safe application for readers. This article is for educational purposes and is not a substitute for personal medical care.
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Natto and nattokinase articles:
- How To Interpret The 10,800 FU Nattokinase Findings Safely
- Could Nattokinase Be Useful In Preventing Alzheimer’s Dementia?
- An Unusual Case of Parkinsonism Improvement After Nattokinase Use
- Laboratory Studies on Nattokinase and Abnormal Protein Aggregates
- An Unusual Case of Prostate and Vascular Symptom Improvement With Nattokinase
- Nattokinase and Stroke Research: Understanding the Evidence
- A Laboratory Study on Nattokinase and the S1 Spike Protein Fragment
- Laboratory Study Shows Nattokinase Can Break Down Spike Protein Fragments
- Could Nattokinase Be Useful In Preventing Alzheimer’s Dementia?
- Nattokinase Degrades Amyloids and Prions
- Natto: An application of the 80-20 Rule
- Should you take nattokinase on an empty stomach?
- How to stop bleeding if on nattokinase
- Natto: An application of the 80-20 Rule
- How I Made and Appreciate Natto
- Insulin Resistance and Atherosclerosis and the Nattokinase Solution
- Protective Effects of Nattokinase against Strokes
- How to dose Nattokinase, Bromelain and NAC
- High-Dose Nattokinase to Shrink Atherosclerosis and Lower Blood Lipids
- Nattokinase is Nontoxic with a High Safety Margin
- The Outstanding Vascular Effects and Dose of Nattokinase
- Soy Foods Do Not Increase Breast Cancer Risk
Disclaimer:
This article is for educational purposes and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your physician before making health decisions based on the TyG Index or other biomarkers.
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