scored 90/100
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.
6.6 g net carbs after fiber.
Representative amounts for this food, not measured for this item. Real content varies widely by variety, ripeness and storage.
These are the scored components, not a sum: the published score also reflects normalisation across the catalog, so the parts above will not add to 90.
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.
Vitamin K2 (menaquinone) activates osteocalcin and matrix Gla protein, proteins essential for directing calcium to bones rather than arterial walls
Fermentation increases amino acid bioavailability and reduces antinutrient factors like phytates, enhancing protein digestibility to near animal-protein levels
Nattokinase, a serine protease produced during fermentation, may help dissolve excess fibrin and support healthy blood flow
Live Bacillus subtilis and partially fermented oligosaccharides feed beneficial bacteria, supporting intestinal barrier function and immune signaling
Fermentation generates GABA (a calming neurotransmitter), while 57mg choline per 100g supports acetylcholine synthesis and brain cell membrane integrity
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.
Breaks a fast
While technically compatible with fasting, consuming natto during eating windows ensures optimal nutrient absorption, particularly for fat-soluble vitamin K2
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.
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.
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.
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).
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).
In a 90 g serving, natto is highest in Copper (~67% DV), Manganese (~60% DV), Iron (~43% DV), Magnesium (~25% DV), Zinc (~25% DV).
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).
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.
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.
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.
Encyclopedia entries that supply the same signature nutrients natto contributes. Click through to see clinical dose ranges, evidence quality, and bioavailable forms.
These are the nutrients natto contributes 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.