natto

Natto is a traditional Japanese food made by fermenting soybeans with the bacterium Bacillus subtilis var. natto. It has a strong, pungent aroma, a slimy, stringy texture, and a tangy flavor that clings to the beans.

Production involves soaking soybeans, then boiling or steaming them before they are inoculated with natto starter culture. The beans are incubated at about 40°C for 18–24 hours to ferment, then cooled and allowed to mature for a day or two. The result is a sticky, stringy mass with a distinct aroma.

Natto is rich in plant-based protein, fiber, and minerals, and is notably high in vitamin K2 (menaquinone), which supports bone and cardiovascular health. It contains the enzyme nattokinase and is often discussed for potential probiotic effects, though results can vary. People taking anticoagulant medications should consult a clinician before regularly consuming natto due to its vitamin K content and potential blood-thinning interactions.

Culinary uses include serving natto over steamed rice with soy sauce and karashi mustard; chopped scallions are a common topping. It can also be stirred into miso soup, blended into sauces, or folded into eggs to add a fermentation note.

Storage and safety: Natto is typically refrigerated and consumed within a week or two after opening; some varieties can be frozen for longer storage. Discard natto that shows off-odors, mold, or an unusual texture.

Varieties differ by aroma, texture, and regional preference. In Japan, some regions favor milder natto while others prefer stronger flavors; international versions may be milder still.