The Nutritional Profile of Natto
Natto is a traditional Japanese dish made from cooked soybeans fermented with a bacteria called Bacillus subtilis. The fermentation process not only gives it a distinctive stringy texture and pungent aroma but also profoundly enhances its nutritional value compared to unfermented soybeans. It is low in calories but exceptionally rich in nutrients that are vital for human health.
A typical 100-gram serving of natto contains a remarkable nutritional profile:
- Protein: Approximately 18-19 grams, providing a complete plant-based protein source.
- Fiber: Around 5-6 grams, which aids digestion and promotes satiety.
- Vitamin K2: An extraordinary amount, with sources suggesting between 600 µg to 1100 µg per 100g serving. This is a vitamin that is difficult to find in plant-based foods.
- Manganese: An essential mineral involved in bone formation and metabolism.
- Iron: Provides a substantial percentage of the daily recommended intake.
- Probiotics: Loaded with beneficial bacteria (Bacillus subtilis) that support a healthy gut microbiome.
Powerful Health Benefits of Natto
The health benefits of natto are wide-ranging and are attributed to its unique nutrient composition.
Promotes Stronger Bones with Vitamin K2
Natto is one of the richest dietary sources of Vitamin K2, a nutrient crucial for bone health. Vitamin K2 plays a key role in activating osteocalcin, a protein that helps bind calcium to the bone matrix. This process not only strengthens bones but also helps prevent osteoporosis, particularly in postmenopausal women. Regular consumption is linked to a reduction in bone mineral density loss.
Boosts Cardiovascular Health
Natto's most celebrated component is nattokinase, a powerful enzyme produced during fermentation that has potent fibrinolytic activity. This means it can break down fibrin, a protein involved in blood clot formation. Studies have shown that nattokinase can help dissolve existing blood clots, improve blood flow, and may help lower blood pressure, making it an excellent food for cardiovascular health. The high Vitamin K2 content also supports arterial health by preventing calcium buildup in arteries. For more in-depth information, you can read research on nattokinase's effects [^1].
Enhances Gut Health and Digestion
As a fermented food, natto is a natural probiotic powerhouse, containing billions of live and active Bacillus subtilis bacteria per serving. These probiotics help populate the gut with beneficial flora, which can improve digestion, regulate bowel movements, and support a healthy immune system. The fermentation process also breaks down anti-nutrients present in raw soybeans, such as phytates, making the nutrients in natto more bioavailable and easier for the body to absorb.
Strengthens the Immune System
A healthy gut is intrinsically linked to a strong immune system. The probiotics in natto bolster the body's natural defenses by supporting a balanced gut microbiome. Natto also contains essential nutrients like vitamin C, manganese, and zinc, which are crucial for immune function.
Natto vs. Other Fermented Soy Products
| Feature | Natto | Tofu | Tempeh |
|---|---|---|---|
| Fermentation | Yes, with Bacillus subtilis | No | Yes, with Rhizopus oligosporus |
| Probiotics | High | None | High |
| Vitamin K2 | Extremely High | None | Low to Moderate |
| Texture | Sticky, stringy, gooey | Soft, smooth, firm | Firm, dense, meaty |
| Flavor | Pungent, nutty, earthy | Mild, neutral | Earthy, nutty, mushroom-like |
| Primary Use | Breakfast food, condiment | Protein source, versatile | Meat substitute |
Potential Risks and Considerations
While natto is exceptionally healthy, there are a few important considerations.
Interaction with Blood Thinners
Individuals on anticoagulant medications like Warfarin should consult their doctor before consuming natto. The extremely high concentration of Vitamin K2 in natto can interfere with these medications, as Vitamin K is essential for blood clotting. Nattokinase also has blood-thinning properties, which can compound this effect.
Soy Allergies
As natto is made from soybeans, it should be avoided by anyone with a soy allergy. Though very rare, it is also possible to develop a specific allergy to natto.
Goitrogenic Effect
Soybeans contain isoflavones, which can have a goitrogenic effect, potentially suppressing thyroid function if consumed in very high amounts. However, the fermentation process and the normal portion sizes of natto mean this is generally not a concern for most people.
Incorporating Natto into Your Diet
For those willing to embrace its unique qualities, natto is versatile. Traditional preparations involve mixing a small packet of natto with the provided soy sauce and mustard and serving it over steamed rice. For beginners, mixing it with other ingredients can help mask the strong flavor and texture.
- Natto with Rice and Toppings: Serve over rice with toppings like chopped scallions, kimchi, grated daikon, or a raw egg yolk.
- Natto Sushi: Use it as a filling for sushi rolls.
- Natto Udon: Mix into chilled udon noodles.
- In Soups and Omelets: Add to miso soup or scrambled eggs.
Conclusion
Natto is an incredibly healthy food, rich in protein, fiber, probiotics, and uniquely high in Vitamin K2 and the powerful enzyme nattokinase. Its benefits for cardiovascular health, bone density, and gut function make it a prized superfood. While its distinctive taste and texture are an acquired preference, the nutritional rewards are significant. Individuals on blood thinners should seek medical advice due to natto's potent effects on blood clotting. For most, integrating natto into a balanced diet can be a potent and delicious way to boost overall wellness.
[^1]: Chen H, et al. Nattokinase: A Promising Alternative in Prevention and Treatment of Cardiovascular Diseases. Biomarker Insights. 2018;13:1177271918785130. doi:10.1177/1177271918785130
