Unique Eats: Natto – Japanese Fermented Soybeans

If you’ve ever taken an interest in unique Japanese foods, chances are you’ve stumbled upon natto (納豆), the fermented soybean dish with the distinct (and strong) smell, the sticky, stringy texture and its deep, beany flavor. It’s likely what you’ve heard about this Japanese dish is either exceedingly positive or all bad, as this food seems to be either loved or hated by many. Even among people living in Japan, many people from eastern Japan could eat natto for every meal, while those from western Japan may refuse to touch it. However, if you like it upon first taste or take the advice of others to “keep eating, it grows on you,” you’ll be able to enjoy the delicious, complex flavor of natto as well as the many health benefits contained in fermented foods.

There are many varying dates cited as to when natto was first made; while so many different dates float around, it’s generally agreed that natto has been around for a Very Long Time, given anywhere from China’s Zhou dynasty (1134-246 BCE) to Japan’s Jomon period (10,000-300 BCE) or even Japan’s Yayoi period (300 BCE to AD 300.) Though varied in the idea of when natto was created, most theories agree that it was probably by accident. These “accidental” theories usually claim that boiled soybeans were left to dry on a straw mat or, while being cooked, some soybeans spilled over onto a straw mat, where they began to ferment due to the rice straw’s high ability to grow Bacillus natto, a healthy bacteria used specifically in the fermentation of natto. When natto was first eaten, it was usually made by farmers for their own consumption, but in the Edo period (1603-1868) as popularity grew, natto vendors began selling natto around town. In these early days, the bacterium used to cultivate natto only grew readily in the fall and winter months, but as times changed and scientists gained a better understanding of the bacterium, people were able to eat natto year-round.


When you buy pre-packaged natto, you usually get a styrofoam container filled with natto, and many varieties come with one or two sauce packets as well. If you buy frozen natto (which is made fresh in Japan and then frozen in order to export to the United States), you first need to thaw it in the refrigerator and eat it immediately afterwards. Don’t just dig right into your natto, though; the next step is the most important step to get your natto to the perfect consistency. Stir your natto for about 60 seconds, upon which you’ll see that your natto has become stringy and sticky, which is just how you want it. If your natto came with sauce packets (usually soy sauce and a hot mustard), this is when you’ll want to empty those into this delicious, sticky mixture. Enjoy your natto alongside a bowl of rice for a truly authentic flavor. Many people also mix their natto into spaghetti sauce, curry, and even put it on sandwiches. Natto is also commonly used in sushi for natto maki (納豆巻), a sushi roll consisting of only seaweed, rice, and natto.

When you buy natto, you’re usually not going to get plain beans in a package; they almost always come with a packet of sauce (usually a soy sauce or something similar) and often they come with a packet of spicy mustard (natto with regular mustard can also be found). Along with the different sauces, there can be any number of different foods mixed into the natto, such as daikon radish and wasabi; if you have some fresh naganegi (ながねぎ), spring onions in English, or negi (ねぎ), scallions in English, natto tastes even more delicious when you chop them up and mix them in. You can also add shredded fresh shiso leaf and mix them in for a great minty-basil, fresh flavor. There are even different varieties based on the beans used: there’s a black bean natto and hikiwari natto (ひきわりなっと), a type of natto made with roasted, split soybeans.

When it comes to eating healthy, natto is a great piece to add to your diet as it mixes the health benefits of soybeans with those found in many fermented foods. Natto even has it’s own special enzyme, called Nattokinase, that’s been found to be uniquely beneficial according to studies from all over the world. Natto, being made from soybeans, is high in protein, fiber, calcium, iron, and vitamins K2, which is great for promoting healthy blood clotting and strengthening bones, as well as vitamin B2. While the vitamin K2 helps healthy blood clotting, the Nattokinase has been shown to break down unneeded blood clots, which is good for helping to prevent heart attacks. Vitamin K2 is also known as the “anti-wrinkle vitamin,” making natto a good food to eat for your skin’s health! Vitamin B2, also called riboflavin, is a very helpful vitamin when it comes to energy and metabolism; it helps greatly in the process the body goes through to change fat into energy. It also helps your blood absorb some of the iron from your daily diet.

Making natto is actually fairly easy to make at home as long as you have the time and space to make the amount you want, the base ingredients (which can be bought at Asahi), and a natto starter. The natto starter is actually the easiest thing to get; as long as you have a pre-made natto (bought fresh or frozen), you have your starter! To start making your natto, first take your soybeans, or daizu (大豆) in Japanese, and put them in a container with some water–a good ratio is one volume of daizu to two~three volumes of water. Make sure you put your beans in a container that’s large enough to hold them once they’ve absorbed all of the water you add. Let your daizu soak overnight and when you wake up, you’ll find that the individual beans have enlarged and become oblong in shape.

From here, you’ll want to steam your daizu; any type of method will work, but the slower you can steam them the better, as you want to try to let them steam for up to three hours, otherwise they may not be open to fermentation. After this point, you want to make sure that all the containers you use to make your natto have been cleaned properly, preferably boiled in hot water, in order to kill any sort of bacteria that may be lurking on them; fermented foods are more susceptible to growing molds or bacteria with which they may come in contact. Use a large, shallow vessel–metal is best as it has less places for bacteria to hide in–and spread your soaked and steamed daizu along the bottom. (This is the point where the natto smell begins to make itself known, so be sure to pick your location carefully!)

This will be where your natto starter comes in. Drop a few beans of your pre-made natto into about 100mL of water (use a good mineral water to better control what additives do and don’t go into your natto). Stir the water and bean mixture around a few times until your water starts to gain a cloudy appearance, and then you have your starter! Pour this mixture into your steamed daizu, making sure to cover the beans evenly, then cover the whole container with plastic wrap, poking holes in the top to allow for proper ventilation. Tap the plastic wrap with your fingers lightly, just to ensure that it is in contact with the top of the beans, but don’t press down and destroy the beans shape.

4 Selfmade_Natto

At this point you want to make sure your natto stays a pretty constant temperature of anywhere between 86 and 104 degrees Fahrenheit (that’s 30-40 Celsius). There are a few tricks to making sure your natto stays at the proper heat such as putting a hot water bottle beside the container and covering both with a blanket or even using a heated blanket over the container. Let your natto ferment for around 20 hours, checking the temperature periodically to make sure it’s staying within the range. When you’re finished, pull off your plastic wrap and you should see that your beans have become covered with a whitish filament. Don’t be alarmed, since this is exactly what you want and shows that everything has gone well and you’ve made your very own natto!

If you’re feeling adventurous and want to try some of this unique food for yourself or you want to take advantage of natto’s many health benefits, you can stop by Asahi any time for a wide selection of frozen natto. You’ll also find MegumiNatto brand’s fresh, never frozen, natto so you can experience the full beany flavor. You can buy some soybeans and even use any of the natto you buy as a starter if you want to try your hand at making your own natto!

So, do you love or hate natto? Ever get someone else to eat natto just to see the look on their face? Are there any unique natto recipes that you love eating? Let everyone know your favorite way to enjoy natto in the comments!

Are there any topics that you’d like to read about on the Asahi blog? Leave a comment below and let us know! Your topic could be the next one we cover!


Leave a Comment

  1. Sirs, I want to learn to make natto. I purchased organic, non GMO, soybeans 6wks packaged in paper bag 50lbs. On opening we discovered thin layer light gray mold. Are these beans usable for natto? Thank You, Bernie @. carbide08@gmail.com

    1. Hi Bernie!

      We’re not natto experts, but our opinion is that you’ll want to get new beans for your natto. You’ll want a specific type of mold in your natto making, and unfortunately that’s not the mold you want.

      Thanks for the question and thanks for reading!

  2. Thank you for this article. The natto I purchased has 0 English on it and didn’t know what the packets were! Plus would you know what the different types of the natto are. The store I was in had ohhh at least 20 different containers but again no English so not a clue what the differences would be.

  3. I don’t find it much of a pleasure eating natto but I am able to eat it frozen. Am I still getting all the nutritional benefits eating it frozen?

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