In recent years, scientific understanding of the gut microbiome has grown and consumers increasingly understand the benefits that a well-balanced gut microbiome can have on general health, from immunity to digestion to cognitive wellness. This has led to a rise in popularity of many traditional fermented foods, such as kefir, kombucha, sauerkraut, and kimchi.
Kimchi is a Korean dish made by fermenting salted cabbage with chilli, garlic, ginger, and other ingredients such as shrimp paste or fish sauce. Previously unknown outside of Korea, sales of this side dish have skyrocketed around the world. Korean producer Daesang, which enjoys 60% of the kimchi export market, reported a 131% increase in exports between 2016 and 2021 and, last year, announced it was building its first European factory in Poland to make kimchi.
Now, some industry stakeholders hope that a little-known side dish from Japan could emulate the success of kimchi.
Natto is made by steaming or cooking soaked soybeans and fermenting them with bacteria, specifically Bacillus subtilis var. natto (also known as Bacillus natto). After a sufficient period of fermentation, the whole soybeans are covered in a white sticky fluid and have a soft texture, slimy appearance, and distinct flavour.
Like cheese, the flavour can vary hugely depending on the length of fermentation, ranging from relatively mild with umami notes to strong, earthy, and pungent.
A good source of protein and fibre, natto also contains vitamin K – it is frequently cited as one of the greatest sources of vitamin K, particularly vitamin K2 – manganese, copper, iron, potassium, magnesium, zinc, and selenium. It also contains nattokinase, an enzyme found in natto, that is said to improve cardiovascular health.
From snacks to side dishes: New product development with natto
Natto is traditionally served on white rice. However, some Japanese packaged food brands use it as a base to make healthy snacks. Freeze drying a popular method to remove the sliminess of fresh natto.
Sonomono, for instance, makes snack-sized packs of freeze dried natto available in three flavours: plain, sea salt, and brown sugar. The Japanese company, which ships globally, describes the brown sugar-flavoured natto snack as “an unexpected encounter of earthy sweetness and savoury natto”, and recommends eating it with yoghurt, ice cream, or cheesecake. It also makes powdered natto supplements for digestive health.
Another Japanese brand, Kanro Puchipori, freeze dries natto soybeans and flavours them with soy sauce in a snack described as being “subtly chewy” and packed full of umami notes.
Still very much a niche food outside Japan, Western brands selling natto tend to focus on the traditional, fresh format. US fermented food brand Rhapsody Foods offers two types of natto, made with either large or small regionally sourced soybeans. The company makes all its products in Vermont and says its aim is to bring the value of traditional dietary practices from Asia to US consumers. German brand Frisch Natto sells throughout Europe.
Adobe / Kristina Blokhin
Making natto palatable with flavours and familiar formats
A recently opened natto concept store in Tokyo allows consumers to create their own natto dish, choosing the texture of soybean (small, large, or coarsely ground) and adding traditional toppings that include dried kelp flakes, kimchi, ume plum, quail egg, bonito flakes, green chilli miso, wasabi, and chilli oil. It also offers natto packed in traditional rice straw or bamboo.
Outside Japan, however, natto’s strong flavour and slimy texture may be off-putting to many people. The US Soybean Export Council (USSEC) sees great potential for natto globally as it taps into interest in both fermented foods and plant-based foods but recognises that it needs to be adapted to Western consumers. It recommends that restaurants serve it as part of well-known dishes – it suggests avocado toast with natto and egg – or as a flavouring ingredient.
“Creating hybrid condiments – combining natto’s umami flavour with mayonnaise or mustard – is a way to introduce foodservice chefs and home cooks to natto as a sandwich spread or dip,” it said in an online post. “Other ideas include balsamic vinegar/natto-glazed roasted root vegetables: adding a bit of vinegar to natto reduces the bold smell and taste of natto. Adding few drops of sesame oil adds flavour to the natto and tends to reduce the smell. Natto can also add robust flavour to salads or pizza.”
USSEC has an interest in growing demand for the product: US soy producers supply around 70% of the soybeans used by Japan’s domestic natto industry. It is counting on education and experimentation to bring natto to a wider global audience outside Japan, and last year organised a three-day summit on natto in partnership with the Japan Natto Cooperative Society Federation, exploring export opportunities, supply chain issues, and food trends.
Its strategy includes promoting natto’s nutrition profile and health benefits; drawing on the cultural significance of natto and sharing stories of its history; and encouraging opportunities where retailers, foodservice operators, and consumers can taste it for themselves.
‘Health is wealth’: Researching natto’s health benefits
As a fermented whole food, natto has a plethora of health benefits. One review listed studies that found natto to have anticancer, anti-inflammatory, and antioxidative properties; an antidiabetic effect; antiallergenic properties; a beneficial impact on gut microbial diversity; and more.
The health benefits of natto are a key selling point for brands. Rhapsody Foods makes a prominent front-of-pack probiotic claim on its products, and researchers are continuing to explore the mechanisms behind natto’s health benefits.
Scientists from Osaka Metropolitan University said they had “demonstrated the possibility of lifespan-extending effects [...] through the ingestion of Bacillus subtilis var. natto” in an April 2023 study, published in the Journal of Applied Microbiology.
Although the research was conducted in a worm model, lead author Professor Eriko Kage-Nakadai said he hoped to apply the research to humans.
The scientists hypothesised that the “significantly longer” lifespan of those fed a natto-based diet may be down to the p38 MAPK pathway and insulin/IGF-1-like signalling pathway, which are known to be involved in immunity and lifespan. They also found that the natto group’s resistance to UV light and oxidative stress was enhanced.
“Health is wealth as the saying goes and new research now shows that it is possible to have a healthy, less stressed society through familiar and inexpensive foods. One such food might be the Japanese natto,” read a statement issued by Osaka Metropolitan University.