Natto: Japan’s Fermented Superfood – Nutrition, Health Benefits & Uses
Discover the unique health benefits, nutrition profile, and culinary uses of natto, Japan’s traditional fermented food—supported by science and tradition.
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Natto: Japan’s Fermented Superfood
Natto, a traditional Japanese food made from steamed and fermented soybeans, is renowned not only for its strong flavor and sticky texture but also for its exceptional nutritional value and numerous health benefits. For centuries, it has been a staple in Japanese breakfasts, offering a powerful dose of protein, vitamins, minerals, and potent bioactive compounds unique to its fermentation process.
What Is Natto?
Natto is created by fermenting whole soybeans with the Bacillus subtilis (natto) bacterium. This process yields its signature sticky, web-like texture and distinctive aroma. While its taste and strong smell may be an acquired preference, natto’s remarkable nutritional profile and health-boosting properties have made it a standout food both in Japan and increasingly worldwide.
Key Characteristics of Natto
- Origin: Japan, with records dating back over a thousand years
- Main Ingredient: Soybeans fermented with Bacillus subtilis
- Texture: Stickiness with thread-like strings
- Flavor: Earthy, pungent, and slightly nutty
Nutritional Profile of Natto
Natto is highly regarded as a nutrient powerhouse. In just a single 100g serving, natto delivers ample amounts of macronutrients, essential minerals, and vitamins, along with unique fermentation-derived compounds.
| Nutrient | Amount per 100g | % Daily Value* |
|---|---|---|
| Calories | 211 kcal | – |
| Protein | 19.4 g | – |
| Total Fat | 11 g | – |
| Carbohydrates | 12.7 g | – |
| Fiber | 5.4 g | – |
| Calcium | 217 mg | 17% |
| Iron | 8.6 mg | 48% |
| Magnesium | 115 mg | 27% |
| Manganese | 1.53 mg | 66% |
| Potassium | 729 mg | 15% |
| Zinc | 3.03 mg | 27% |
| Vitamin K | 23.1 mcg | 19% |
| Vitamin C | 13 mg | 14% |
| Selenium | 8.8 mcg | 16% |
*Percent Daily Value is based on a 2,000 calorie diet
Key Nutritional Highlights
- High in Protein: Nearly 20 grams per serving, making it an excellent plant-based source—especially for vegetarians and vegans.
- Rich in Fiber: Promotes satiety and supports digestive health.
- Excellent Source of Micronutrients: Contains significant levels of calcium, iron, magnesium, potassium, and manganese.
- Vitamin K2: Exceptionally high compared to most foods; vital for bone and cardiovascular health.
- Probiotics and Bioactive Compounds: Contains beneficial bacteria and unique fermentation metabolites such as nattokinase.
How Is Natto Made?
The traditional preparation of natto relies on a two-step process:
- Steaming the Soybeans: Soybeans are soaked, then cooked by steaming until soft.
- Fermentation: Beans are combined with Bacillus subtilis natto, then incubated at a warm temperature for around 24 hours. This process activates fermentation, transforming texture, flavor, and nutrition.
Aging enhances stickiness—the distinctive threadlike texture is a direct result of this fermentation.
Top Health Benefits of Natto
Natto provides a robust array of health benefits, many of which stem from its unique composition that is only possible due to fermentation.
1. Abundant in Nutrients and Easily Absorbed
Fermentation not only increases vitamin and mineral content in natto, but also breaks down antinutrients such as phytates, lectins, and oxalates, which normally inhibit absorption. As a result, the body is able to absorb and utilize these nutrients more efficiently than from unfermented soybeans.
- High levels of protein, fiber, vitamins (notably vitamin K2), and minerals.
- Improved digestibility compared to non-fermented soy foods.
2. Supports Gut Health
Natto is a natural source of probiotics from the live bacteria generated during fermentation, particularly Bacillus subtilis. Regular consumption supports healthy gut flora, improves digestion, and bolsters immune function.
- Helps maintain balanced intestinal microbiota.
- May reduce symptoms of indigestion and improve absorption of other nutrients.
3. Enhances Heart Health
Perhaps the most celebrated compound in natto is nattokinase, an enzyme unique to this food. Nattokinase has demonstrated the ability to support cardiovascular health through several mechanisms:
- Reduces Blood Clot Risk: Nattokinase can promote the breakdown of blood clots (fibrinolysis), potentially lowering the risk of strokes and heart attacks.
- Supports Healthy Blood Pressure: Some studies suggest regular natto intake may help maintain normal blood pressure levels.
- Improves Circulation: Aids blood flow and may benefit those prone to poor vascular health.
4. Promotes Strong Bones
Natto contains among the highest natural levels of vitamin K2 (menaquinone-7), which plays a crucial role in bone metabolism by activating proteins that bind calcium, thus strengthening bone tissue and reducing the risk of osteoporosis.
- Particularly beneficial for postmenopausal women and adults at risk of osteoporosis.
- Dietary vitamin K2 from natto has been linked to improved bone mineral density.
5. May Support Immune Function
The symbiosis of probiotics, bioactive peptides, and micronutrients in natto can contribute to a healthier immune response. Probiotics contribute to gut barrier integrity and immune signaling, while other antioxidants may help protect cells from oxidative damage.
Other Potential Health Benefits
- May Help Lower Cholesterol: Certain bioactive compounds and fiber in natto may help maintain healthy blood lipids.
- Blood Sugar Regulation: The fiber and protein content support stable blood glucose.
- Weight Management: Its high satiating properties can help curb cravings and overconsumption.
How to Eat Natto
Natto can be enjoyed in a variety of ways, both traditional and creative. While its smell and texture may be challenging for some, proper preparation and pairing can make natto more palatable, even for newcomers.
Popular Ways to Enjoy Natto
- With Rice: The classic way is to mix natto with soy sauce, mustard, or green onions and serve over steamed rice.
- As a Sushi Ingredient: Used as natto-maki (fermented soybean sushi rolls).
- Mixed into Salads: Adding vegetables and sesame seeds for nutrition and crunch.
- In Miso Soup: Adds protein and probiotic richness to soups.
- Breakfast Dishes: Natto with egg, seaweed, and avocado on toast is gaining popularity outside Japan.
Tip: If you’re new to natto, try mixing it with flavorful condiments or blending it into dishes with bold flavors to balance its strong taste.
Potential Side Effects and Considerations
- Vitamin K Content: Individuals taking blood thinners (like warfarin) should avoid excessive natto due to its high vitamin K, which can interfere with medication.
- Histamine/Soy Sensitivity: As a soy product, those with soy allergies or sensitivity should avoid natto.
- Texture and Flavor: The taste and stickiness can be off-putting; gradual introduction may help tolerance.
Comparing Natto with Other Fermented Soy Foods
| Food | Main Characteristics | Key Benefits |
|---|---|---|
| Natto | Fermented whole soybeans (sticky, strong smell) | Probiotics, vitamin K2, nattokinase, improved digestion |
| Miso | Fermented soy paste, usually used in soups | Probiotics (if unpasteurized), umami flavor |
| Tempeh | Fermented soy pressed into firm blocks | High protein, firm texture, easy meat substitute |
| Soy Sauce | Liquid from fermented soy and wheat | Flavor enhancement, some antioxidants |
Natto in Japanese Culture & Cuisine
Natto is especially popular in eastern Japan, often paired with rice as a breakfast staple. While some regions have a long-standing natto tradition, its taste remains polarizing even among the Japanese. Despite this, natto’s reputation as a food that aids longevity and supports good health is widespread and well-documented.
Frequently Asked Questions (FAQs)
Q: What makes natto so healthy compared to other soy foods?
A: Natto’s fermentation process dramatically increases its nutritional value and digestibility, introducing unique compounds like vitamin K2 and nattokinase not found in most other soy products. It’s also easier to absorb essential minerals and vitamins from natto.
Q: Is natto suitable for vegans and vegetarians?
A: Yes, natto is fully plant-based and provides strong protein, iron, and calcium for those avoiding animal products.
Q: Are there any health risks in eating natto regularly?
A: Most people can enjoy natto safely, but those on blood thinners or with soy allergies should consult their healthcare provider before adding large amounts to their diet, due to its high vitamin K and soy content.
Q: Can you make natto at home?
A: Yes. Natto can be made by fermenting cooked soybeans with Bacillus subtilis natto starter culture and incubating in a warm environment, but the process requires attention to hygiene and temperature control for best results.
Q: How often should one eat natto for health benefits?
A: No official guidelines exist, but many Japanese people eat natto several times per week as part of a balanced diet. One serving (about 100g) a few times a week is thought to provide benefits for most adults.
Key Takeaways
- Natto is a nutritional powerhouse, rich in proteins, vitamins, minerals, probiotics, vitamin K2, and a unique enzyme nattokinase.
- Scientific research links regular natto consumption to improved heart, bone, and gut health.
- It is a versatile food with a distinctive taste—acquired by many, but valued for health worldwide.
References
- https://www.healthline.com/nutrition/natto
- https://draxe.com/nutrition/natto/
- https://bokksu.com/blogs/news/natto-101-everything-you-need-to-know-about-japans-nutritional-powerhouse
- https://www.webmd.com/diet/health-benefits-nattokinase
- https://revolutionfermentation.com/en/blogs/tempeh-soy-grains/health-benefits-natto/
- https://www.urmc.rochester.edu/encyclopedia/Content?contentTypeID=76&ContentID=16113-1
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