Natto: Japan’s Fermented Soybean Tradition, Regional Styles, and How to Eat It
Natto — soybeans fermented with Bacillus subtilis var. natto bacteria to produce sticky, stringy, pungent beans — is one of Japan’s most polarizing foods, deeply beloved by a large portion of the population and categorically rejected by many first-time tasters. The fermentation process produces a complex flavor profile combining umami, bitterness, and a pungent ammonia-like note; the sticky strands that form when the beans are stirred are a textural experience without Western equivalent. For travelers curious about Japanese food culture, engaging seriously with natto offers insight into fermentation traditions, regional identity, and the Japanese relationship between food and health.
Fermentation and Production
Natto production begins with soaking and steaming whole soybeans, then inoculating them with Bacillus subtilis natto spores and incubating at approximately 40°C for 12–18 hours. During fermentation, the bacteria produce the characteristic stickiness (polyglutamic acid polymers) and the pungent aroma compounds. The fermented beans are then chilled to arrest fermentation and packed in the small polystyrene containers (traditionally pine straw bundles — waratsuto) that are ubiquitous in Japanese supermarket refrigerators.
Nutritionally, natto is exceptional: it contains nattokinase (an enzyme associated with cardiovascular health), vitamin K2, complete protein, and a dense probiotic community. The fermentation process increases bioavailability of the soybeans’ nutrients compared to cooked unfermented soybeans. These properties have sustained natto’s status as a health food in Japan for over a millennium.
Regional Natto Culture
Mito (Ibaraki Prefecture): Japan’s most famous natto city — the city’s identity is built around natto to a degree unusual even in Japan. Mito Station gift shops are stocked almost exclusively with natto products; natto ice cream, natto pasta, natto rice crackers, and natto soft-serve are all sold alongside standard small-pack fermented beans. The city’s Mito Natto Co-op produces several premium varieties. Natto festivals are held regularly; the city claims historical connections to natto production dating to the Edo period.
Tohoku: The highest per-capita natto consumption region in Japan — the cold climate historically made natto a practical protein source during winter. Larger beans (okutama or hikiwari chopped style) and regional producer varieties with distinctive flavor profiles are found in Tohoku supermarkets.
Kansai: The cultural boundary of natto preference runs roughly at the old Tokai-Kanto border — Kansai residents historically have lower natto consumption, and the region is associated with light-colored miso and different fermentation traditions. This cultural divide is itself a frequently discussed aspect of Japanese regional identity.
How to Eat Natto
Standard preparation: stir the beans vigorously (50–100 rotations is conventional wisdom for developing the stickiness fully), add the included tare (soy sauce seasoning) and mustard packets, and serve over hot rice. Common additions include chopped green onion, raw egg yolk, kimchi, or minced takuan (pickled daikon). The beans should be lifted with chopsticks and eaten with rice; the sticky strands are an expected and valued part of the experience. Most Japanese eat natto at breakfast as the protein component of a traditional Japanese meal.
For visitors trying natto for the first time: the initial scent impact is strongest when the package is first opened; it diminishes once the beans are stirred and mixed with rice. Eating cold natto on its own maximizes the challenging aspects; eating freshly stirred, well-seasoned natto on hot rice in the context of a complete Japanese breakfast is the optimal introduction.
Natto Beyond Breakfast
Contemporary Japanese cuisine extends natto into unexpected contexts. Natto pasta (a 1990s fusion dish now mainstream at Italian chain Saizeriya) combines natto with spaghetti and nori. Natto maki (sushi rolls) are a lunchtime staple. Natto pizza, natto toast, and natto udon are regional variations; the fermented beans appear in tempura (natto in shiso leaf), on pizza in chain restaurants, and in craft beer (seasonal collaborations between natto producers and microbreweries). This creative application reflects both natto’s cultural status as a health food and its producers’ efforts to expand consumption among younger Japanese who grew up without the daily breakfast habit.