What is Natto?

Natto is a fermented food made by fermenting soybeans using bacteria called “Bacillus subtilis.” However, whilst living in Spain, I had no starter, so I decided to experiment with fermenting the beans using cabbage leaves. The outcome was excellent.


According to the oldest tale surrounding the creation of natto, it was thought up somewhere around the 10th century BC and the middle of the 3rd century AD.

It is believed that it started getting sold as a product in the Edo period (1603 – 1868), eventually becoming a standard part of the Japanese breakfast. It is extremely popular as a healthy delicacy, possessing plenty of Vitamin K, soy protein, and dietary fiber.

Since it is a fermented food, it does give off a special smell that comes from the bacteria. Due to its unique stickiness, texture, and taste, it is a food that some people don’t like, it is an acquired taste. It has a flavour that has been described as akin to fermented cheese and is often served with condiments such as sliced green onions, wasabi or pickled ginger.

Soybeans Wrapped in Rice Straw

It’s not quite certain when or who first discovered that wrapping cooked soybeans in rice straw for a while would make them ferment and become soft and sticky. The earliest written record of natto is from around the mid-11th century, but it is fairly certain that the food itself existed way before then.

The bacillus bacteria that turns soybeans into natto, bacillus subtilis or bacillus nattō, lives on rice straw, and since both rice and soybeans have existed in Japan since prehistoric times, it’s quite likely that natto has been made since then, too.

The old-fashioned way of making natto, by wrapping boiled soybeans in straw and keeping them in a warm place for a few days, gave me the idea to warp them in cabbage leaves, as bacteria live on them, as well. Lactobacillus Plantarum is the most popular lactic acid bacteria strain and it ferments sauerkraut, pickles, cheese, and even meat.

There are a lot of good reasons to try using natto in your diet.

Whole cooked, soybeans are packed with protein, fiber and other nutrients, but the fermentation process makes it even more beneficial to health: It adds probiotics, which helps with digestion as well as strengthening the immune system. It’s also packed with vitamin K, which is found in leafy greens as well as vitamin PQQ (pyrroloquinoline quinone), which may help your body’s cells to metabolize.

How I Make Natto

  • 1 1/2 cups organic soybeans
  • Cabbage leaves
  • Baking tray
  • Coolbox
  • Glass jars

Wash and rinse the soybeans. Soak for a maximum for 10 hours, the beans will absorb to at least double in size. Place in a pressure cooker with enough water to cover and bring to a boil.

Skim off the foam that arises and when the foam ceases, cover the pressure cooker and cook at low heat for 30 minutes.

Remove from the heat and allow the pressure to come down naturally.

If you don’t have a pressure cooker, use an open pot, however, you will have to add water as the beans cook. Follow the same format, skimming off the foam, then cover and cook over medium heat until the beans are soft.

Drain the beans and set aside. Cover the base of the baking tray with the cabbage leaves, discarding any hard stems, so the leaves lay flat. Spread the beans on top and then cover with a layer of cabbage leaves, tucking in the sides of the tray.

Transfer the tray to your coolbox or any other box with a tight lid you may have to hand.

Place one or two sushi mats on top to avoid squashing the beans when you add your water bottles or jars. Fill your glass jars with hot water from the tap and place in each corner of the box or depending on the size of your jars or bottles that may lie horizontally.

I refreshed the warm water every 12 hours for a period of 36 hours. Perfectly fermented, stringy, sticky natto was the result. Your choice to freeze in portions or refrigerate. Freezing stops the fermentation process and preserves the stickiness. Without refrigerating, the natto will lose its stickiness and continue to ferment.

Note: In Spain, the fermentation happened simply with the cabbage leaves, but here in the U.K. damp wet winter right now, you must follow the method above.

In good health,




Natto contains fiber, probiotics, vitamin K2 and nattokinase. This combination may help reduce cholesterol and blood pressure levels and decrease the risk of heart disease.

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A long-time vegan, lover of animals, nature and life and passionate about human ecology. As an eternal optimist, increasing the number of people worldwide to switch to a wholefood, plant-based diet and vegan lifestyle is her mission. Together with her husband Bill Tara, they have created The Human Ecology Project.