Natto is a traditional Japanese food that has gained a reputation as a powerful superfood, particularly for those seeking to enhance their gut, heart, and bone health. Made from soybeans fermented with Bacillus subtilis natto bacteria, its characteristic strong aroma and slimy texture are a direct result of the fermentation process that also produces its impressive nutritional profile. For centuries, natto has been a dietary staple, and modern scientific research is increasingly validating the health wisdom passed down through generations.
The Probiotic Powerhouse for Gut Health
One of the most widely recognized benefits of natto comes from its probiotic content. The fermentation with Bacillus subtilis results in a dense population of beneficial bacteria that supports a healthy and diverse gut microbiome. This has several positive effects on digestive health:
- Improved Digestion and Nutrient Absorption: The probiotics in natto help break down food and enhance the absorption of vitamins and minerals. The fermentation process also neutralizes some of the natural antinutrients found in soybeans, making the food easier to digest.
- Relief from Digestive Issues: A balanced gut flora can help alleviate symptoms of digestive problems like gas, bloating, constipation, and diarrhea.
- Enhanced Immune Function: A significant portion of the immune system resides in the gut. A healthy microbiome, supported by probiotics, helps to strengthen the body's natural defenses against pathogens.
Nattokinase: A Heart-Healthy Enzyme
Another remarkable compound unique to natto is nattokinase, an enzyme produced during the fermentation process. Nattokinase is a potent fibrinolytic enzyme, meaning it helps to dissolve fibrin, a protein involved in blood clotting. Research has explored its potential cardiovascular benefits:
- Dissolving Blood Clots: By breaking down blood clots, nattokinase can help maintain good blood vessel structure and improve overall blood flow. This action may protect against heart disease and conditions caused by blood clots, such as stroke.
- Lowering Blood Pressure: Some studies suggest that regular consumption of nattokinase can help lower blood pressure, reducing the strain on the heart.
- Reducing Cholesterol: The fiber and polyunsaturated fats present in natto can help reduce LDL cholesterol levels, contributing to overall heart health.
Bolstering Bones with a Vitamin K2 Boost
Natto is considered the richest known food source of Vitamin K2, a crucial nutrient for bone health that is not widely available in most modern diets. Unlike Vitamin K1, found in leafy greens, Vitamin K2 is vital for regulating calcium in the body:
- Calcium Regulation: Vitamin K2 activates proteins that help transport calcium from the bloodstream into the bones and teeth, where it is most needed.
- Preventing Arterial Calcification: By directing calcium away from soft tissues, K2 helps prevent it from building up in the arteries, keeping them supple and elastic.
- Increased Bone Density: Studies have shown that Vitamin K2 supplementation can help increase bone mineral density and reduce the risk of fractures, especially in postmenopausal women.
Beyond the Big Three: Other Notable Nutrients
In addition to its powerful probiotic and enzymatic properties, natto is a nutrient-dense food packed with other essential vitamins and minerals.
- High-Quality Protein: Natto is an excellent source of complete, plant-based protein, providing all the essential amino acids necessary for muscle repair and growth.
- Fiber: The high fiber content supports digestive health, promotes satiety, and aids in weight management.
- Key Minerals: Natto is rich in minerals such as iron, manganese, magnesium, calcium, and zinc, all of which play vital roles in overall health.
Natto vs. Other Soy Products: A Nutritional Comparison
To highlight the unique benefits of fermentation, here is a comparison of natto with other common soy products, based on an average serving size.
| Feature | Natto | Tofu | Edamame |
|---|---|---|---|
| Processing | Fermented | Curdled | Steamed |
| Probiotics | Yes (live cultures) | No | No |
| Vitamin K2 (as MK-7) | Extremely High (richest source) | Low to none | Low to none |
| Digestibility | High (anti-nutrients broken down) | Moderate | Moderate |
| Nattokinase Enzyme | Yes (unique to fermentation) | No | No |
How to Embrace Natto: Tips for First-Timers
For those new to natto, its unique texture and pungent smell can be off-putting. Here are some tips to make it more palatable:
- Stir Vigorously: Before eating, stir the natto with chopsticks for a minute or two. This creates the signature stringy texture and is believed to enhance the umami flavor.
- Add Flavorful Condiments: Mix in the included packets of tare (soy sauce) and karashi (mustard). Chopped green onions are also a popular and effective addition.
- Combine with Other Foods: Serve natto over warm rice, mix it into scrambled eggs, or use it as a topping for toast or pasta to help mask the flavor and texture.
- Try Regional Varieties: Some people find that smaller bean varieties or hikiwari natto (crushed beans) are more palatable and produce a stronger Vitamin K2 concentration.
Important Considerations Before Eating Natto
While generally safe for most people, there are some important considerations to keep in mind, especially regarding its potent nutrients:
- Blood-Thinning Medication: Due to its high Vitamin K content and nattokinase enzyme, natto can thin the blood. Individuals on blood-thinning medications like warfarin should consult a doctor before adding natto to their diet to avoid potential interactions.
- Soy Allergies and Thyroid Issues: As a soy product, natto should be avoided by those with a soy allergy. People with impaired thyroid function may also want to limit their intake, as soy is considered a goitrogen, though this is less of a concern with fermented soy.
Conclusion: A Small Package of Powerful Benefits
For those willing to embrace its distinctive qualities, natto offers an exceptional array of health benefits that go far beyond a typical breakfast food. As a concentrated source of probiotics, the unique enzyme nattokinase, and the highly bioavailable Vitamin K2, natto supports everything from robust gut health and immune function to cardiovascular wellness and bone strength. Its rich content of protein, fiber, and essential minerals further cements its status as a legitimate superfood. Incorporating this traditional Japanese delicacy into a balanced diet can provide a powerful nutritional boost, making the effort to acquire a taste for it a worthwhile health investment. For a more detailed look at nattokinase's effects, see this Biochemical Research International review.
