What Is Natto Food?

Natto is a traditional Japanese fermented soybean dish known for its sticky texture, strong aroma, and rich probiotic benefits.

The Origins and History of Natto

Natto has been a staple in Japanese cuisine for centuries, dating back over a thousand years. It is believed to have originated during the Jomon period, with some stories tracing its discovery to accidental fermentation of boiled soybeans wrapped in rice straw. The natural bacteria present in rice straw, Bacillus subtilis natto, initiates the fermentation process that transforms the soybeans into natto.

This food became popular not just for its unique taste but also for its nutritional value and health benefits. Traditionally eaten as a breakfast item in Japan, natto pairs well with rice and condiments like soy sauce, mustard, or green onions. Its sticky texture and pungent smell can be off-putting to those unfamiliar with it, but it remains beloved by many for its deep umami flavor.

What Exactly Is Natto Food?

At its core, natto is fermented soybeans. The fermentation process involves steaming or boiling soybeans and then inoculating them with Bacillus subtilis bacteria. This bacterium breaks down proteins and carbohydrates in the beans, producing a distinctive sticky substance called polyglutamic acid. This sticky coating is responsible for the slimy texture that sets natto apart from other soybean products.

The fermentation not only alters the texture but also enhances the nutritional profile of the soybeans significantly. Natto is rich in protein, vitamins (notably vitamin K2), minerals, and enzymes that support digestion. The probiotics generated during fermentation contribute to gut health by promoting beneficial bacteria balance.

The Science Behind Natto’s Unique Texture and Smell

Natto’s characteristic stickiness comes from polyglutamic acid (PGA), a natural polymer produced by Bacillus subtilis. PGA acts as a natural glue binding the beans together with long strands of mucus-like threads. This sliminess can be surprising at first but is central to natto’s identity.

The strong aroma often described as “earthy” or “ammonia-like” results from fermentation by-products such as ammonia and various volatile compounds. While some find this smell unpleasant initially, it mellows when mixed with rice or other ingredients.

Nutritional Breakdown of Natto

Natto stands out nutritionally compared to regular cooked soybeans due to fermentation enhancing nutrient bioavailability and adding probiotics. Here’s an overview of what makes natto a powerhouse food:

Nutrient	Amount per 100g	Benefit
Protein	18.7 g	Supports muscle growth & repair
Vitamin K2 (Menaquinone-7)	1103 µg	Essential for bone & heart health
Fiber	5.4 g	Aids digestion & regulates blood sugar
Iron	8.6 mg	Vital for oxygen transport in blood
Calcium	217 mg	Strengthens bones & teeth
Probiotics (live bacteria)	High concentration*	Boosts gut microbiome & immunity

*Exact probiotic counts vary based on production methods but are significant enough to influence digestive health positively.

The Role of Vitamin K2 in Natto

Vitamin K2 found abundantly in natto is particularly noteworthy because it plays a critical role in calcium metabolism—helping direct calcium into bones and away from arteries where it can cause harm. Most Western diets lack sufficient vitamin K2, making natto an excellent natural source.

Research links vitamin K2 intake with reduced risk of osteoporosis and cardiovascular diseases. This makes natto especially beneficial for older adults or those concerned about bone density.

Key Takeaways: What Is Natto Food?

➤ Fermented soybeans with a strong aroma and sticky texture.

➤ Rich in protein and beneficial probiotics for digestion.

➤ Popular in Japan as a traditional breakfast food.

➤ Known for health benefits like improved heart health.

➤ Acquired taste, often paired with rice and soy sauce.

Frequently Asked Questions

Natto is a traditional Japanese dish made from fermented soybeans. It is known for its sticky texture and strong aroma, which result from the fermentation process involving Bacillus subtilis bacteria. Natto is rich in protein, vitamins, and probiotics that support digestive health.

How Is Natto Food Made?

Natto is made by steaming or boiling soybeans and then fermenting them with Bacillus subtilis natto bacteria. This fermentation produces a sticky coating called polyglutamic acid, which gives natto its unique slimy texture and enhances its nutritional value.

Why Does Natto Food Have a Strong Smell?

The strong smell of natto comes from fermentation by-products like ammonia and other volatile compounds. While the aroma can be off-putting at first, it softens when eaten with rice or condiments, making it more enjoyable for many people.

What Are the Health Benefits of Natto Food?

Natto is packed with probiotics that improve gut health by promoting beneficial bacteria. It also provides vitamin K2, protein, minerals, and enzymes that help digestion and support overall wellness. Its fermentation process increases nutrient absorption compared to regular soybeans.

How Is Natto Food Traditionally Eaten?

In Japan, natto is commonly eaten as a breakfast food served over rice. It is often combined with soy sauce, mustard, or green onions to complement its strong flavor and sticky texture. This traditional pairing helps balance natto’s unique taste.

The Fermentation Process Explained Step-by-Step

Producing authentic natto involves careful control of temperature, humidity, and time to encourage Bacillus subtilis growth while preventing harmful microbes:

Selecting Soybeans: High-quality whole soybeans are soaked overnight to soften.
Cooking: The beans are steamed or boiled until tender but intact.
Inoculation: Beans are mixed with Bacillus subtilis culture—either naturally from rice straw or added directly.
Fermentation: Beans are kept at around 40°C (104°F) for 18-24 hours allowing bacteria to multiply.
Maturation: After fermentation, natto is cooled quickly and refrigerated to slow further bacterial activity.
Packaging: Once matured, it’s packaged fresh or frozen for distribution.

This process creates the signature sticky strands and pungent aroma while preserving nutrients.

Differences Between Homemade and Commercial Natto

Making natto at home can be rewarding but challenging due to precise temperature needs and contamination risks. Commercial producers use controlled environments ensuring consistent quality.

Homemade versions might vary more in texture or smell depending on local bacterial strains used during fermentation. Commercially produced natto typically uses pure cultures resulting in milder flavors preferred by some consumers outside Japan.

Culinary Uses: How Natto Is Enjoyed Around the World

In Japan, natto is most commonly served over hot steamed rice with simple toppings like soy sauce, karashi mustard, chopped green onions, or raw egg yolk mixed in for richness.

Beyond traditional uses:

Sushi Rolls: Natto maki rolls combine fermented beans wrapped in seaweed with sushi rice.
Natto Toast: A modern twist spreads natto on toast topped with cheese or avocado.
Natto Salad: Mixed into salads with fresh vegetables for added protein boost.
Natto Pasta: Stirred into warm pasta dishes as an umami enhancer replacing heavier sauces.

Outside Japan, adventurous eaters incorporate it into smoothies or dips due to its probiotic content despite its strong taste profile.

Taste Profile: What Does Natto Actually Taste Like?

Natto’s flavor combines earthiness with nuttiness plus a hint of bitterness from fermentation acids. The aroma can be intense—some compare it to aged cheese—while others find it reminiscent of mushrooms or soy sauce.

Its slimy texture might take some getting used to; however mixing thoroughly before eating helps distribute flavors evenly across each bite making it more pleasant.

The Health Benefits Backed by Science

Natto offers several scientifically supported health advantages:

Digestion Support: Its live probiotics improve gut flora balance aiding digestion and reducing bloating.
Cancer Prevention Potential:* Some studies suggest compounds in fermented soy can inhibit cancer cell growth.
CVD Risk Reduction:* Vitamin K2 lowers arterial calcification risk; fiber also helps manage cholesterol levels.
Bones & Teeth Strengthening:* High calcium combined with vitamin K2 enhances bone mineral density.
Aiding Blood Clotting:* Vitamin K plays a vital role in coagulation processes preventing excessive bleeding.

*While promising data exists from lab studies and population research, more clinical trials are necessary for definitive claims.

Natto Compared With Other Fermented Foods

Unlike yogurt or kimchi which rely primarily on lactic acid bacteria producing sourness, natto uses Bacillus subtilis, creating more alkaline conditions resulting in unique textures and flavors.

Here’s how natto stacks up nutritionally against common fermented foods:

Name	Main Bacteria Type	Main Nutritional Highlight(s)
Natto	Bacillus subtilis (natto)	B Vitamin complex; Vitamin K2; Protein; Probiotics;
Kefir (milk-based)	Lactobacillus species + yeasts	Lactose digestion aid; Calcium; Probiotics;
Kimchi (fermented vegetables)	Lactic acid bacteria (Lactobacillus)	P Vitamins; Fiber; Antioxidants;
Sauerkraut (fermented cabbage)	Lactic acid bacteria (Leuconostoc)	C Vitamins; Fiber; Probiotics;

Each fermented food has distinct benefits depending on bacterial strains involved and base ingredients used.

The Challenges: Why Some People Avoid Natto Food?

Despite its benefits, several factors limit widespread acceptance:

The strong odor can be overwhelming especially for first-timers unaccustomed to fermented foods.
The slimy consistency may feel strange or unpleasant compared to familiar textures like cooked beans or tofu.
Natto contains high levels of vitamin K which can interfere with blood-thinning medications such as warfarin — making medical consultation necessary before consumption.
Cultural familiarity plays a big role; outside Japan many consumers simply haven’t been introduced properly so they shy away based on appearance alone.

Understanding these barriers helps producers develop milder versions or incorporate flavors that make eating natto easier globally.

Nutritional Considerations Before Adding Natto To Your Diet

If you’re considering adding this superfood regularly:

If you take anticoagulants consult your healthcare provider first since vitamin K impacts medication effectiveness.
Add gradually if you’re new to fermented foods — this allows your digestive system time to adjust without discomfort.
Avoid if you have soy allergies as natto derives directly from whole soybeans.

If pregnant or breastfeeding check safety guidelines since fermented foods vary widely worldwide based on preparation hygiene standards.