Natto is a Japanese superfood made from fermented soybeans using Bacillus subtilis bacteria. This low-calorie food packs protein (19g per 100g), fiber, probiotics, and key nutrients like vitamin K2 (menaquinone), iron, magnesium, and zinc. Fermentation boosts bioavailability, reduces antinutrients, and creates nattokinase—a powerful enzyme that supports heart health by dissolving blood clots and lowering blood pressure.
Natto promotes gut health with probiotics and fiber, easing digestion and reducing inflammation. Vitamin K2 strengthens bones, while isoflavones and antioxidants support skin, immunity, and hormone balance. It may also aid weight control, sinus health, and brain function.
Start small if new to its sticky texture—mix with rice, soy sauce, or use in soups. Safe for most, but avoid if allergic to soy or on blood thinners. A nutrient-dense, heart-smart choice backed by tradition and science.
Long Version
Natto Nutrition & Health Benefits: Japan’s Fermented Superfood
Natto, a traditional Japanese superfood made from fermented soybeans, has been a staple in Japan for over a thousand years. This unique food undergoes fermentation using the bacterium Bacillus subtilis, transforming simple soybeans into a nutrient-packed powerhouse with a distinctive sticky texture and earthy flavor. As a low-calorie option rich in probiotics, natto stands out for its impressive nutrition profile and wide-ranging health benefits, from supporting digestive health to promoting cardiovascular health. Whether you’re exploring gut health or seeking natural ways to enhance your immune system, natto offers valuable insights into how fermentation can elevate everyday soybeans into a superfood with profound impacts on well-being.
The Fermentation Process Behind Natto
Natto’s creation begins with whole soybeans that are soaked, boiled, and then inoculated with Bacillus subtilis, a beneficial bacterium that drives the fermentation process. This step typically occurs at around 100°F for 22–24 hours, during which the bacteria produce enzymes and bioactive components essential to natto’s health properties. The result is a stringy, mucilaginous product owing to polyglutamic acid (PGA), a natural polymer formed during fermentation. This process not only enhances the probiotic potential but also breaks down antinutrients in soybeans, making the nutrients more bioavailable. Historically, natto was fermented using rice straw, but modern methods use pure cultures for consistency and safety.
Comprehensive Nutritional Profile of Natto
Natto is a nutrient-dense food, providing a balanced mix of macronutrients and micronutrients in a relatively low-calorie package. A typical 100-gram serving contains approximately 211 calories, with 19.4 grams of protein, 12.7 grams of carbohydrates (including 5.4 grams of dietary fiber), and 11 grams of fat, primarily polyunsaturated. This high-protein content makes it an excellent plant-based option for muscle maintenance and satiety, while the fiber supports steady energy release and helps regulate blood sugar.
On the micronutrient front, natto shines with vitamins and minerals. It delivers substantial amounts of vitamin K (including vitamin K2, also known as menaquinone), which is crucial for bone health and blood clotting. A 100-gram portion provides about 23.1 micrograms of vitamin K, alongside 13 milligrams of vitamin C for immune support. Natto also contains vitamin PQQ (pyrroloquinoline quinone), a compound produced by Bacillus subtilis that acts as an antioxidant and supports cellular energy production. Mineral-wise, it’s loaded with iron (8.6 milligrams, aiding oxygen transport and preventing anemia), magnesium (115 milligrams for nerve function and muscle relaxation), calcium (217 milligrams for bone strength), potassium (729 milligrams to balance electrolytes), zinc (3.03 milligrams for skin health and immune function), copper (0.667 milligrams for collagen formation), manganese (1.53 milligrams for metabolism), and selenium (8.8 micrograms as an antioxidant). Smaller amounts of B vitamins like thiamin, riboflavin, B6, folate, and pantothenic acid further contribute to energy metabolism and overall vitality.
Compared to unfermented soybeans, natto’s fermentation boosts its probiotic content and reduces phytic acid, improving mineral absorption. This makes it a superior choice for those seeking a fermented superfood that’s both filling and nutrient-rich without excess calories. Additionally, the fermentation process increases the bioavailability of isoflavones, plant compounds with hormone-balancing and anti-inflammatory effects, adding another layer to its nutritional superiority.
Key Health Benefits of Natto
Natto’s health benefits stem from its unique combination of probiotics, enzymes, and bioactive components, backed by scientific studies. These effects touch on multiple body systems, making it a versatile addition to a balanced diet.
Digestive Health and Gut Health
As a fermented food, natto excels in promoting digestive health through its probiotic potential. The Bacillus subtilis bacteria survive the digestive tract, acting as beneficial microbes that enhance gut flora balance. This supports gut health by reducing bloating, constipation, and inflammation, while the high dietary fiber (about 5.4 grams per 100 grams) aids motility and prevents metabolic disorders. Studies show that probiotics in natto can improve symptoms of irritable bowel syndrome and ulcerative colitis by optimizing the microbiome and protecting against harmful bacteria. The fermentation process also generates bioactive components like polyglutamic acid (PGA), which contributes to a healthy gut lining. Furthermore, regular consumption may help in maintaining a diverse gut microbiota, which is linked to better overall metabolic health and reduced risk of gastrointestinal disorders.
Heart Health and Cardiovascular Support
Natto is renowned for its cardiovascular health benefits, largely due to nattokinase, a powerful enzyme with fibrinolytic and anticoagulant properties. This enzyme dissolves blood clots, improves blood flow, and reduces arterial plaque, lowering the risk of heart disease and stroke. Research links regular natto consumption to decreased blood pressure and cholesterol levels, with fiber and polyunsaturated fats playing supporting roles in reducing LDL cholesterol. Populations with high natto intake, such as in Japan, show lower mortality from ischemic heart diseases, underscoring its role in heart health. Additionally, isoflavones in natto act as phytoestrogens, further aiding blood vessel health and potentially cleansing the blood by reducing oxidative stress. The combined effects of these components can also help in managing hypertension and improving endothelial function, which is vital for long-term vascular integrity.
Bone Health
Vitamin K2 (menaquinone) in natto is a standout for bone health, helping direct calcium to bones and preventing its buildup in arteries. Combined with calcium, magnesium, manganese, zinc, and copper, it supports bone density and reduces fracture risk, particularly in postmenopausal women. Studies on Japanese populations demonstrate that higher natto intake correlates with improved bone mineral density in the hip and femoral neck, offering protection against osteoporosis. This synergy of nutrients not only strengthens bones but also supports joint health, potentially alleviating conditions like arthritis through anti-inflammatory pathways.
Immune System Boost
Natto strengthens the immune system through its probiotics and nutrient synergy. The gut microbiome influenced by Bacillus subtilis enhances antibody production and reduces infection risk, with a study showing fewer respiratory infections in elderly individuals consuming it. Vitamins C, iron, zinc, selenium, and copper further bolster immune defenses, speeding recovery from illnesses and acting as antioxidants to combat free radicals. This comprehensive support can be particularly beneficial during seasonal changes or for those with weakened immunity, helping to modulate immune responses and prevent overreactions like allergies.
Additional Benefits: Skin Health, Inflammation, and More
Beyond core areas, natto’s isoflavones and soy protein reduce inflammation by inhibiting cytokines like TNF-α and IL-6, potentially easing menopausal symptoms and chronic conditions. For skin health, zinc and copper promote collagen production and wound healing, while antioxidants like vitamin PQQ support cellular repair. Natto may also aid weight management by promoting satiety through protein and fiber, and preliminary research suggests it lowers cancer risk via isoflavones and vitamin K2. Its nattokinase even benefits sinus health by thinning mucus and shrinking nasal polyps, and it enhances metabolism to help regulate body fat and prevent diabetes. Emerging evidence also points to natto’s role in supporting brain health, as vitamin PQQ may protect against neurodegenerative diseases by promoting nerve growth and reducing oxidative damage in neural tissues.
Potential Risks and Considerations
While natto is safe for most, it may cause digestive issues like gas or bloating in those unaccustomed to high-fiber foods. Individuals with soy allergies should avoid it, as symptoms can range from hives to anaphylaxis. Its vitamin K content can interfere with blood-thinning medications like warfarin, and nattokinase may heighten bleeding risks when combined with aspirin. Those with thyroid issues should monitor intake due to goitrogens in soy, though fermentation mitigates this. Pregnant or breastfeeding individuals should consult a doctor, as more research is needed. Starting with small portions can help minimize initial side effects, and opting for organic or non-GMO varieties ensures higher quality and fewer potential contaminants.
Incorporating Natto into Your Diet
Start small to acquire a taste for natto’s umami flavor. In Japan, it’s often mixed with soy sauce, mustard, and chives over rice. Try it in salads, soups, or as a topping for toast. For homemade natto, soak and boil soybeans, add a starter culture, and ferment—store in the fridge for up to a week or freeze for longer. Pair with complementary foods like kimchi or seaweed to enhance its benefits. For those new to it, blending natto into smoothies or using it in dressings can mask its texture while still delivering the nutrients. Experimenting with recipes from various cuisines can make integration easier and more enjoyable.
Conclusion
Natto, Japan’s fermented superfood, exemplifies how simple soybeans can become a multifaceted health ally through fermentation. With its rich array of protein, fiber, vitamins, minerals, and bioactive components like nattokinase and isoflavones, it delivers tangible benefits for digestive health, heart health, bone health, immune system support, and beyond. Backed by scientific evidence, natto remains an accessible, authoritative resource for those pursuing natural wellness—proving that this ancient food continues to offer modern insights into optimal nutrition.
