What Is Natto? Taste, Nutrition & How to Eat Japanese Fermented Soya Beans

Sticky, stringy and unmistakably distinctive, natto is one of Japan’s best-known traditional fermented foods.

In Japan, natto is an everyday food that is often served with warm rice, including at breakfast. In the UK, however, you may know the name without being quite sure what natto tastes like, why it is so sticky or how you are supposed to eat it.

Natto is a traditional Japanese food made by fermenting cooked soya beans with natto bacteria. It is known for its sticky texture, distinctive aroma and savoury flavour.

In this guide, we answer the most common questions about natto: what it is, what it tastes like, how it is made, how Japanese people eat it, how to try natto as a beginner, and what its calories and key nutrients look like. We will also explain how you can enjoy Japanese natto at home in the UK.

■ What Is Natto?

Natto is a traditional Japanese food made from cooked soya beans fermented with Bacillus subtilis var. natto, commonly known as natto bacteria.

In English, the food is usually still called natto. If someone has never heard of it before, it can also be described as Japanese fermented soya beans or fermented soybeans.

Japan has several types of fermented soybean products, but the sticky natto most people recognise is known as itohiki natto, or stringy natto. Japan’s Ministry of Agriculture, Forestry and Fisheries (MAFF) describes it as a soybean food produced by fermenting cooked beans with natto bacteria.

Natto is widely available in Japan and is commonly sold in small individual packs. Many packs include a small sachet of sauce and sometimes mustard, making it easy to mix and eat straight from the pack once prepared according to the product instructions.

For someone trying natto for the first time, its aroma and long sticky strings can be surprising. Those characteristics, however, are also what make natto such a distinctive part of Japanese food culture.

■ What Does Natto Taste Like?

Natto has a rich, savoury flavour with earthy, slightly nutty notes and the distinctive character of fermented soya beans.

Its flavour can be described with words such as:

• savoury
• earthy
• nutty
• fermented

For many first-time eaters, however, the most surprising part is not the flavour but the aroma and texture.

When natto is stirred, it becomes increasingly sticky and develops long, fine strings. The texture is unlike most foods commonly eaten in the UK.

In one sense, natto can be compared with Marmite: not because the two taste the same, but because both can inspire strong opinions. Some people love natto immediately, while others need a little time to get used to its aroma and texture.

If you are new to natto, try it with warm rice rather than tasting a large spoonful on its own. Rice softens the overall impression and makes the savoury flavour easier to enjoy.

■ Why Is Natto Sticky?

Natto becomes sticky during fermentation, when natto bacteria act on the cooked soya beans and create the characteristic stringy texture associated with the food.

Natto is not simply boiled or steamed soya beans. The beans are inoculated with natto bacteria and fermented under controlled conditions. During this process, natto develops its characteristic aroma, flavour and sticky texture.

Stirring the natto before eating makes the strings more noticeable and creates a lighter, frothier consistency around the beans.

For many Japanese people, mixing natto thoroughly before adding sauce or mustard is part of the familiar ritual of eating it.

■ How Is Natto Made?

Natto is made by cooking soya beans, adding natto bacteria, fermenting the beans under controlled temperature and humidity, then cooling and maturing the finished natto.

According to MAFF, Bacillus subtilis var. natto is applied to the soybeans before they are packed into containers and fermented in rooms where temperature and humidity are carefully controlled. The natto is then cooled and matured.

The basic process can be understood in six stages:

1. Prepare the soya beans.
2. Cook them until tender.
3. Add natto bacteria.
4. Ferment under controlled temperature and humidity.
5. Cool and mature the natto.
6. The natto is ready.

The process may sound simple, but MAFF notes that temperature and humidity control from fermentation through maturation is an important part of producing good natto.

There are also different styles of natto. Hikiwari natto, for example, is made from split beans rather than whole beans. Its smaller texture makes it particularly easy to mix into rice, sushi and other dishes.

■ How Do Japanese People Eat Natto?

The most familiar way to eat natto in Japan is to mix it well, season it with sauce or mustard, and serve it over warm Japanese rice.

Depending on personal preference, natto can also be combined with ingredients such as:

• soy sauce or the sauce included in the pack
• karashi mustard
• finely sliced spring onion
• nori
• bonito flakes
• egg
• grated daikon
• kimchi

Warm Japanese rice is an especially good starting point. Its gentle sweetness and soft texture balance the fermented flavour and sticky texture of natto.

Is Natto Eaten for Breakfast?

Yes. Natto is commonly eaten at breakfast in Japan, although there is no rule about when you should eat it.

A simple Japanese-style breakfast might include rice, miso soup, natto and pickles. Natto can just as easily be eaten at lunch or dinner.

■ How to Eat Natto as a Beginner

If you are trying natto for the first time, the easiest approach is to mix it well, add the supplied sauce or mustard, and eat a small amount over warm rice.

Here is a simple step-by-step guide.

Step 1: Prepare the Natto

If your natto is frozen, defrost it according to the instructions on the packaging. Storage and preparation instructions can vary between products, so always check the label.

Step 2: Open the Pack

Remove the lid and any film covering the beans. If your natto comes with sauce or mustard, keep the sachets to one side for the moment.

Step 3: Stir the Natto Well

Use chopsticks to stir the beans. As you mix, the natto will become stickier and the familiar white strings will develop.

Step 4: Add Sauce or Mustard

Add the included sauce and mustard to taste, then mix again. For beginners, the seasoning can make the fermented flavour feel more rounded and familiar.

Step 5: Serve It Over Warm Rice

For your first taste, keep things simple with natto and Japanese rice.

If the aroma feels strong, try adding spring onion or nori. You do not need to eat a large amount at once: start with a small portion and experiment with different toppings until you find a combination you enjoy.

■ Natto Nutrition: Calories, Protein, Fibre and Vitamin K

Natto is a fermented soya-bean food that provides protein, fibre and vitamin K, alongside other nutrients naturally found in soya beans.

According to Japan’s Standard Tables of Food Composition 2023, published through the Ministry of Education, Culture, Sports, Science and Technology (MEXT), 100g of standard stringy natto contains the following:

A typical retail pack of natto may contain considerably less than 100g, and nutrition can vary by product, portion size and any sauce or seasoning included.

For the most accurate calories and nutrition information for the natto you are eating, always check the nutrition label on the product packaging.

What About Vitamin K?

Natto is particularly high in vitamin K. The MEXT food composition database lists 600μg of vitamin K per 100g of standard stringy natto.

■ Easy Ways to Enjoy Natto at Home

Natto does not have to be eaten only with plain rice. Once you become familiar with the flavour and texture, it can be used in a wide range of simple dishes.

・ Natto Rice

The classic option and one of the easiest ways to start.

Serve seasoned natto over freshly cooked Japanese rice, then add spring onion or nori if you like.

・ Natto Sushi

Natto is also used as a sushi filling in Japan.

Natto maki, or a natto sushi roll, is a simple combination of sushi rice, nori and natto. Hikiwari natto is particularly convenient because its smaller pieces are easy to spread along the rice before rolling.

・ Natto & Kimchi

Mixing natto with kimchi adds acidity, chilli heat and extra savoury flavour. It can be a useful combination for anyone who finds the flavour of plain natto a little strong at first.

・ Natto Toast

For an easy UK-friendly twist, try natto on toast.

You can serve seasoned natto on toasted bread or combine it with ingredients such as cheese for a completely different way to experience its savoury flavour.

・ Natto with Noodles

Natto can also be added to udon or soba. Spring onion, nori and grated daikon are simple accompaniments that work particularly well.

There is no single “correct” way to enjoy natto. Starting with foods you already know and like can make your first experience much easier.

■ Can You Buy Natto in the UK?

Yes. Natto is available in the UK from Japanese and Asian food shops as well as specialist online retailers.

Yutaka Shop Online has a dedicated Natto Collection featuring Japanese natto, including small-bean and hikiwari varieties. Availability changes, so check the collection page for the latest range.

If you are new to natto, smaller individual packs can be a convenient way to try different styles and find the texture you prefer.

■ Recommended Natto to Try

If you are not sure which natto to choose, these two small-grain varieties are good places to start. Both come in convenient individual portions, but each has a different character.

■ Frequently Asked Questions About Natto

■ Ready to Discover Natto?

Natto can look, smell and feel unusual when you try it for the first time – and that is part of what makes it such an interesting Japanese food.

Its distinctive sticky texture comes from fermentation, while its savoury flavour can be enjoyed in many ways, from a simple bowl of natto rice to sushi, noodles, toast and kimchi.

Start with a small amount over warm rice. Once you become familiar with it, experiment with spring onion, nori, mustard or your favourite toppings.

If you would like to try Japanese natto in the UK, explore the Yutaka Shop Online Natto Collection and discover which style suits you best.

■ Sources

• Ministry of Agriculture, Forestry and Fisheries of Japan (MAFF) – Natto

  Information on natto production, fermentation with Bacillus subtilis var. natto, temperature and humidity control, cooling and maturation.

  View the official MAFF source
• Ministry of Education, Culture, Sports, Science and Technology (MEXT) – Standard Tables of Food Composition

  Nutrition information for standard stringy natto, including energy, protein, fat, fibre and vitamin K per 100g.

  View the official MEXT food database
• UK Medicines and Healthcare products Regulatory Agency (MHRA)

  Guidance for people taking warfarin on maintaining a consistent intake of vitamin-K-rich foods.

  View the MHRA guidance
• Yutaka Shop Online – Natto (Fermented Soybeans)

  Information on the UK Natto Collection, available product types and common ways to enjoy natto.

  View the Natto Collection