Natto
Natto is fermented soybeans with a distinctive sticky, pungent character that delivers high-quality plant protein, probiotics, and vitamin K2—a form crucial for bone and cardiovascular health that is rarely found in plant sources.
Nutrition · per ~90 g serving · ≈ ½ cup cooked
- Vitamin K20.8 mcg17% DV
- Riboflavin0.17 mg13% DV
- Vitamin C11.7 mg13% DV
- Thiamin0.14 mg12% DV
- Vitamin B60.19 mg11% DV
- Choline51.3 mg9% DV
- Folate7.2 mcg2% DV
- Vitamin E0.01 mg<1% DV
- Copper0.60 mg67% DV
- Manganese1.4 mg60% DV
- Iron7.7 mg43% DV
- Zinc2.7 mg25% DV
- Magnesium103.5 mg25% DV
- Calcium195.3 mg15% DV
- Selenium7.9 mcg14% DV
- Potassium656.1 mg14% DV
- Phosphorus156.6 mg13% DV
- Sodium6.3 mg<1% DV
- Polyunsaturated Fat5.6 g
- Monounsaturated Fat2.2 g
- Saturated Fat1.4 g
- Inulin / Prebiotic fibre~2.7 g
- Live probioticslive cultures
- Choline~135 mg
Score · 90/100
Vitamins & minerals packed in relative to calories — the single biggest driver of the score.
How much protein it delivers, by absolute grams and per calorie.
Dietary fiber for gut health, satiety and steadier blood sugar.
Fat quality — unsaturated vs saturated, and trans-fat free.
Polyphenols, flavonoids and other beneficial plant compounds for this food group.
Low sugar with a high fiber-to-carb ratio scores best — gentler on blood sugar.
- Copper74% DV
- Manganese66% DV
- Iron48% DV
- Zinc28% DV
- Magnesium27% DV
Overview
Natto originates from Japan, where it has been a dietary staple for over 1,000 years. During fermentation by Bacillus subtilis, soybeans undergo a remarkable biochemical transformation: proteins become more bioavailable, complex carbohydrates are partially broken down, and—most notably—vitamin K2 (menaquinone) is synthesized de novo. A 100g serving provides 211 calories with nearly 20g of complete plant protein, substantial micronutrients including iron (8.6mg), and bioactive compounds including nattokinase, a fibrinolytic enzyme with emerging cardiovascular benefits. The fermentation process also generates live probiotics and GABA, both linked to gut and neurological health. For longevity-focused nutrition, natto's combination of K2, complete protein, and fermented bioactives makes it exceptionally valuable—particularly for populations with limited access to K2-rich animal products. The sticky mucopolysaccharide coating (produced during fermentation) may support digestive resilience. Natto's umami-rich flavor makes it a functional food that enhances palatability of nutrient-dense meals without added sodium.
Health Benefits (5)
- Supports bone mineralization and cardiovascular calcification prevention via vitamin K2moderateVitamin K2 (menaquinone) activates osteocalcin and matrix Gla protein, proteins essential for directing calcium to bones rather than arterial walls
- Provides complete plant-based protein with all nine essential amino acidsstrongFermentation increases amino acid bioavailability and reduces antinutrient factors like phytates, enhancing protein digestibility to near animal-protein levels
- Supports fibrinolytic activity and healthy blood viscosity via nattokinaseemergingNattokinase, a serine protease produced during fermentation, may help dissolve excess fibrin and support healthy blood flow
- Promotes healthy gut microbiota composition via probiotics and prebiotic carbohydratesmoderateLive Bacillus subtilis and partially fermented oligosaccharides feed beneficial bacteria, supporting intestinal barrier function and immune signaling
- Supports cognitive and mood health via GABA and choline contentmoderateFermentation generates GABA (a calming neurotransmitter), while 57mg choline per 100g supports acetylcholine synthesis and brain cell membrane integrity
Food Pairings
- ·Pair with brown rice or soba noodles because their complex carbohydrates slow gastric emptying, extending nutrient absorption and moderating blood glucose response
- ·Combine with raw leafy greens (spinach, arugula) because natto's vitamin K2 works synergistically with K1 from greens for comprehensive bone and vascular support
- ·Serve with fermented vegetables (kimchi, sauerkraut) because complementary probiotic species enhance microbial diversity and reinforce intestinal barrier integrity
- ·Mix with avocado or olive oil because natto's fat-soluble vitamin K2 absorption is enhanced by dietary lipids
Practical Tips
- ·Purchase frozen natto packages and thaw overnight in the refrigerator; freeze immediately upon arrival if not used within 2-3 days, as Bacillus viability declines with age
- ·Mix natto vigorously for 30-50 seconds before eating to maximize the development of mucopolysaccharides and activate nattokinase; stir with the provided condiment packet for optimal flavor and umami enhancement
- ·Consume natto in its raw, unheated form to preserve heat-sensitive probiotics, nattokinase activity, and vitamin K2; heating above 70°C significantly reduces bioactive enzyme activity
- ·Start with a small portion (1-2 tablespoons) if new to natto to allow digestive adaptation; some individuals experience temporary bloating as the microbiome adjusts to increased fermented foods
- ·Store unopened packages in the freezer (below -18°C) for up to 6 months; once thawed, keep refrigerated and consume within 24-48 hours for optimal probiotic viability
Optimal Timing
Natto's complete protein, probiotics, and K2 support multiple physiological processes that benefit from distributed intake throughout the day. However, consuming with meals (especially breakfast or lunch) maximizes fat-soluble K2 absorption and provides sustained protein availability for satiety and muscle protein synthesis.
While technically compatible with fasting, consuming natto during eating windows ensures optimal nutrient absorption, particularly for fat-soluble vitamin K2
Systems supported
body systems this food feedsPathways supported
biochemical reactions enabled by this foodCompared to other legumes
Per 100 g of the default form. Bars show how much higher or lower natto is than the average across 26 peer foods in this category. Green means a favorable direction; amber means the opposite.
What people ask about natto
What is natto?
Natto is classified as a legume. Natto is fermented soybeans with a distinctive sticky, pungent character that delivers high-quality plant protein, probiotics, and vitamin K2—a form crucial for bone and cardiovascular health that is rarely found in plant sources.
Is natto healthy?
Natto scores 90/100 in Formulate, making it an exceptional choice. Its strongest contributions come from Copper, Manganese, Iron. The score blends nutrient density, fiber, healthy fats, protein quality, bioactive compounds, and glycemic impact.
Is natto high in protein?
Yes — it's a high-protein food. A 90 g serving provides about 17.5 g of protein (~35% of the 50 g daily value).
Is natto high in fiber?
It's a moderate source of fiber. A 90 g serving provides about 4.9 g of fiber (~17% of the 28 g daily value).
What vitamins and minerals are in natto?
In a 90 g serving, natto is highest in Copper (~67% DV), Manganese (~60% DV), Iron (~43% DV), Magnesium (~25% DV), Zinc (~25% DV).
Is natto keto-friendly?
Sometimes — it depends on your daily carb budget. A 90 g serving has about 6.6 g of net carbs (11.4 g total minus 4.9 g fiber).
When is the best time to eat natto?
Best any time of day. Natto's complete protein, probiotics, and K2 support multiple physiological processes that benefit from distributed intake throughout the day. However, consuming with meals (especially breakfast or lunch) maximizes fat-soluble K2 absorption and provides sustained protein availability for satiety and muscle protein synthesis.
How much natto should I eat?
A typical serving is around 90 g (~190 kcal), based on the FDA's Reference Amount Customarily Consumed for this food category. There's no fixed daily target — most adults benefit from rotating natto alongside several other legume sources.
What pairs well with natto?
Natto pairs nicely with: Pair with brown rice or soba noodles because their complex carbohydrates slow gastric emptying, extending nutrient absorption and moderating blood glucose response; Combine with raw leafy greens (spinach, arugula) because natto's vitamin K2 works synergistically with K1 from greens for comprehensive bone and vascular support; Serve with fermented vegetables (kimchi, sauerkraut) because complementary probiotic species enhance microbial diversity and reinforce intestinal barrier integrity; Mix with avocado or olive oil because natto's fat-soluble vitamin K2 absorption is enhanced by dietary lipids.
Supplements that mirror Natto's nutrient profile
Encyclopedia entries that supply the same signature nutrients natto contributes. Click through to see clinical dose ranges, evidence quality, and bioavailable forms.
Signature nutrients in Natto
These are the nutrients nattocontributes meaningfully toward (≥10% DV per 100 g serving). Click one to see what it does in the body, which supplements concentrate it, and which other foods are top sources.