What is Natto?
Natto is a traditional Japanese food made by fermenting cooked soybeans with a special strain of bacteria known as Bacillus subtilis var. natto. This fermentation process is responsible for its famously pungent, ammonia-like odor and distinctively sticky, slimy texture. While its sensory profile can be divisive, natto has been a staple in the Japanese diet for centuries and is revered for its potent health properties. The fermentation not only creates unique enzymes and flavors but also increases the bioavailability of many nutrients, making them easier for the body to absorb.
The Nutritional Powerhouse: Natto's Profile
From a nutritional standpoint, natto is a powerhouse. A typical 100-gram serving (about 3.5 ounces) packs a significant amount of nutrients for a relatively low-calorie count.
Key Nutrients in 100g of Natto:
- Protein: Around 19 grams, providing a substantial plant-based protein source.
- Dietary Fiber: Approximately 5.4 grams, which is excellent for digestive health.
- Vitamin K2: An exceptionally rich source, offering hundreds of micrograms.
- Manganese: High levels to support brain and nerve function.
- Iron: Significant iron content, promoting healthy blood.
- Calcium: A dairy-free source that is vital for bone health.
- Magnesium: High levels support muscle and nerve function.
- Probiotics: Live Bacillus subtilis cultures contribute to gut microbiome health.
Vitamin K2: Natto's Secret Weapon
One of the most impressive and unique health benefits of natto is its incredibly high concentration of Vitamin K2, specifically the highly bioavailable form known as menaquinone-7 (MK-7). Fermentation by Bacillus subtilis multiplies the vitamin K2 content far beyond that of unfermented soybeans.
Why Vitamin K2 Matters
Vitamin K2 plays a critical role in directing calcium to the right places in the body. It activates specific proteins, ensuring that calcium is incorporated into the bones and teeth while simultaneously preventing its buildup in arteries and soft tissues. This mechanism is why regular natto consumption has been linked to better bone mineral density and lower risk of fractures, especially in postmenopausal women. It may also reduce the risk of arterial calcification, a major risk factor for heart disease.
Nattokinase: The Heart Health Enzyme
During fermentation, the Bacillus subtilis natto bacteria produce a unique enzyme called nattokinase, which is responsible for the sticky, stringy texture. Research has shown that nattokinase possesses potent fibrinolytic activity, meaning it can help dissolve blood clots. This property makes it a valuable asset for cardiovascular health. Studies have also indicated that nattokinase can help lower blood pressure, improve blood flow, and potentially reduce the risk of heart attack and stroke. Due to these benefits, nattokinase is also sold as a dietary supplement.
A Probiotic Powerhouse for Gut Health
As a fermented food, natto is an excellent source of probiotics, the beneficial bacteria that support a healthy gut microbiome. The specific probiotic bacterium, Bacillus subtilis var. natto, is known to be robust, surviving the harsh conditions of the human digestive tract.
Benefits for the Microbiome
- Promotes beneficial bacteria: Studies have shown that consuming natto can increase the abundance of beneficial bacteria, such as Bifidobacterium, in the gut.
- Improved nutrient absorption: The fermentation process and the presence of live cultures can aid in digestion and enhance the absorption of nutrients.
- Supports immune function: A healthy gut microbiome is fundamental to a robust immune system, and natto's probiotic content contributes to this.
- Fights harmful bacteria: The Bacillus subtilis natto strain has also demonstrated antibacterial properties against certain harmful bacteria, such as E. coli.
Comparing Natto with Other Fermented Soy Products
Natto is not the only fermented soy product, but it stands out due to its unique profile. Here is a comparison with other popular options like miso and tempeh.
| Feature | Natto | Miso | Tempeh |
|---|---|---|---|
| Fermenting Agent | Bacillus subtilis var. natto | Aspergillus oryzae (mold) | Rhizopus oligosporus (fungus) |
| Key Unique Compound | Nattokinase and exceptionally high Vitamin K2 (MK-7) | Rich in probiotics and enzymes | Provides isoflavones and is easily digestible |
| Nutrient Profile | High protein, fiber, Vit K2, manganese, iron | High in sodium, minerals, and probiotics | Firm, cake-like texture; high protein and fiber |
| Texture | Sticky, slimy, and stringy | Smooth paste | Firm, meaty, and dense |
| Taste | Pungent, savory, umami | Salty and umami | Nutty and earthy |
Potential Considerations and Side Effects
While natto is overwhelmingly healthy for most people, there are a few considerations to keep in mind.
1. Warfarin and Blood Thinners: Due to its extremely high Vitamin K2 content, natto can interfere with the effectiveness of anticoagulant medications like warfarin. It is crucial for anyone taking blood thinners to consult their doctor before adding natto to their diet to ensure proper dosage adjustment and monitoring.
2. Soy Allergies: As a product of fermented soybeans, natto should be avoided by individuals with soy allergies.
3. Digestive Discomfort: For those unaccustomed to high-fiber foods, consuming large amounts of natto might initially cause digestive discomfort like gas or bloating. Starting with smaller portions allows the body to adjust.
4. Calorie Density: Natto is relatively calorie-dense, so moderation is key for weight management, though its fiber and protein can aid in satiety.
Conclusion
Beyond its challenging texture and aroma, natto is indeed a remarkably healthy food. The fermentation process transforms simple soybeans into a nutritional powerhouse, brimming with beneficial compounds like the potent enzyme nattokinase and an unparalleled amount of Vitamin K2. These elements, along with its probiotic content, offer significant benefits for cardiovascular health, bone density, and the digestive system. While those on blood thinners must exercise caution, incorporating natto into a balanced diet is a scientifically backed way to boost overall wellness, as highlighted by numerous research studies. This ancient Japanese superfood proves that the most potent health benefits can sometimes come in the most unusual of packages. For those seeking to integrate more nutritious, plant-based foods, the benefits certainly outweigh the unique flavor and texture profile.
Learn more about fermented foods and their benefits by visiting the National Institutes of Health (NIH) website for extensive research information.
