Natto, a traditional Japanese dish made from fermented soybeans, is celebrated globally for its nutritional value and unique health-promoting properties. While its strong smell and sticky texture are an acquired taste for many, the science behind what does natto do for your body is increasingly clear. Fermented by the Bacillus subtilis natto bacteria, this superfood contains unique enzymes and high concentrations of vitamins that are not found in unfermented soybeans.
Heart Health: Nattokinase and its Role
One of natto's most significant contributions to your body is its support for cardiovascular health, primarily due to the enzyme nattokinase. Produced during the fermentation process, this powerful enzyme has demonstrated impressive fibrinolytic activity, meaning it can help dissolve blood clots. Studies have explored its potential to lower blood pressure and reduce blood lipid levels, both crucial factors in preventing heart disease. For example, one trial involving hypertensive individuals showed that nattokinase consumption helped improve their blood pressure. Furthermore, nattokinase has been shown to prevent plaque formation in the arteries, which is another key mechanism for safeguarding heart health. The fermentation process also creates soluble soy protein and isoflavones, which have been linked to reduced cholesterol levels and improved arterial health.
Digestive Wellness: Probiotics and Fiber
As a fermented food, natto is a natural source of powerful probiotics, which are beneficial microorganisms that help balance the gut microbiome. A healthy gut microbiome is essential for optimal digestion, a strong immune system, and even mental health. The living Bacillus subtilis spores in natto survive their journey through the digestive system and populate the gut with beneficial bacteria. Natto is also packed with prebiotic fiber, which acts as food for the good bacteria in your gut, further supporting digestive function. This potent combination of prebiotics and probiotics helps to relieve issues such as gas and constipation and can improve symptoms of Irritable Bowel Syndrome (IBS). The fermentation process breaks down anti-nutrients present in soybeans, making the fiber and protein in natto easier for the body to absorb.
Bone Strength: The Power of Vitamin K2
Natto is arguably the best food source of vitamin K2, a crucial nutrient for bone health. While most Western diets contain vitamin K1 from green vegetables, vitamin K2 is found in higher concentrations in fermented foods. It plays a vital role in activating proteins that integrate calcium into bone mineral density, strengthening your bones and protecting against fractures. Proper vitamin K2 intake ensures that calcium is deposited in the bones where it belongs, rather than accumulating in the arteries. This dual action benefits both your skeletal and cardiovascular systems. Research suggests a link between sufficient vitamin K2 intake and a lower risk of osteoporosis, particularly in postmenopausal women.
Anti-inflammatory and Other Benefits
Beyond its well-known effects on the heart, gut, and bones, natto offers additional advantages. Soy isoflavones and peptides like lunasin, found in soybeans and enhanced through fermentation, possess anti-inflammatory properties. By reducing inflammatory cytokines, these compounds can help mitigate chronic inflammation, which is a factor in many metabolic and inflammatory disorders. Natto also boasts a high content of potent antioxidants, such as superoxide dismutase (SOD), which helps combat free radical damage and oxidative stress. The diverse nutrient profile, including manganese, iron, and zinc, also plays a role in boosting overall immune function. Some studies even suggest a potential role in blood sugar regulation.
Natto vs. Other Fermented Soy Products
To understand natto's unique position, it's helpful to compare it to other popular fermented soy foods. This table highlights some key differences in their nutritional profiles and uses.
| Feature | Natto | Miso | Tempeh |
|---|---|---|---|
| Fermentation Agent | Bacillus subtilis natto | Mold (Aspergillus oryzae), yeast, and bacteria | Mold (Rhizopus oligosporus) |
| Key Enzyme | Nattokinase | Various enzymes, but no nattokinase | Various enzymes, but no nattokinase |
| Vitamin K2 Content | Exceptionally high | Low to moderate | Moderate |
| Texture | Sticky, slimy, stringy | Paste | Firm, cake-like |
| Culinary Use | Often eaten as is with rice, mixed into soups, or on toast | Flavoring paste for soups, glazes, and dressings | Cooked, fried, or baked as a meat alternative |
How to Integrate Natto into Your Diet
For those new to natto, its strong flavor and sticky texture can be a hurdle. Start by eating small amounts and gradually increase your intake. A traditional Japanese method involves stirring the natto vigorously with chopsticks for a minute or two to produce a frothy, stringy texture before mixing in the provided soy sauce (tare) and mustard (karashi). Serve it over warm rice to temper the strong flavor.
For a more modern approach, consider these ideas:
- Natto Toast: Spread prepared natto on toast and top with a slice of cheese before toasting. The cheese helps mask the potent flavor.
- Natto Miso Soup: Add natto to your morning miso soup for a quick nutritional boost.
- Natto Sushi Rolls: Use hikiwari (crushed natto) for an easy-to-manage filling in sushi rolls.
- Natto Omelet: Mix natto with chopped green onions and a raw egg before cooking it into a tamagoyaki or simple omelet.
Conclusion
The question of what does natto do for your body is answered by its unique nutritional profile, particularly its high concentrations of nattokinase and vitamin K2, along with its probiotic content. Regular consumption of this fermented food can contribute significantly to better heart health, stronger bones, and a more robust digestive system. While the flavor and texture are an acquired taste, the health benefits are undeniable and well-supported by scientific research. As with any food, listen to your body and start with small portions to reap the maximum rewards from this Japanese superfood.
[Disclaimer: It is important to consult a healthcare professional before making significant dietary changes, especially if you have pre-existing health conditions or take medications like blood thinners due to natto's vitamin K2 content.]
