🫘Natto
The single richest dietary source of Vitamin K2 MK-7 — one serving of natto provides over 1000% of the daily Vitamin K2 requirement, alongside nattokinase with documented clot-dissolving cardiovascular benefits, exceptional probiotics and the most bioavailable soy protein available, making natto arguably the most therapeutically potent fermented food in existence.
What It Is
Natto is a traditional Japanese food made by fermenting soybeans with Bacillus subtilis natto — a bacteria that transforms the nutritional profile of soybeans dramatically. The result is a sticky, stringy, pungent fermented food with an extremely polarizing flavor that is beloved in Japan and largely unfamiliar elsewhere. Natto is nutritionally unlike any other food in a remarkable way — it is by far the richest dietary source of Vitamin K2 MK-7.
MK-7 is the most bioavailable and longest-lasting form of Vitamin K2, with a half-life of 3 days compared to MK-4's half-life of hours. This means a single daily serving of natto provides sustained Vitamin K2 activity throughout the day, directing calcium into bones and away from arterial walls. Natto also contains nattokinase — a serine protease enzyme produced by B. subtilis that dissolves fibrin blood clots and has been extensively studied as a natural thrombolytic agent.
Nutritional Highlights
Health Benefits
- 100g provides over 1000mcg of MK-7 — approximately 10 times the daily adequate intake
- MK-7 has a 3-day half-life — one daily serving maintains elevated K2 activity throughout the day and night
- Activates osteocalcin for bone calcium incorporation — clinically proven to increase bone mineral density
Why it works: Natto's MK-7 is the most pharmacologically active dietary Vitamin K2 — its 3-day half-life means even intermittent consumption maintains adequate K2 activity. Multiple clinical trials confirm that MK-7 supplementation (at doses matching natto consumption) significantly increases bone mineral density and reduces fracture risk in postmenopausal women.
- Nattokinase dissolves fibrin blood clots through serine protease activity
- Clinical trials confirm nattokinase reduces blood pressure and markers of arterial stiffness
- Reduces fibrinogen — the clot-forming protein associated with cardiovascular disease risk
Why it works: Nattokinase is a fibrinolytic enzyme — it directly dissolves the fibrin threads that form blood clots. Clinical trials in Japan and elsewhere have confirmed that oral nattokinase (from natto consumption or supplements) reduces blood pressure, arterial stiffness and fibrinogen levels. This thrombolytic activity makes natto uniquely relevant for cardiovascular disease prevention.
- MK-7 activates matrix GLA protein — the primary inhibitor of arterial calcification
- Arterial calcification reversal observed in research with adequate K2 intake
- Population studies link higher K2 intake to dramatically reduced cardiovascular mortality
Why it works: Matrix GLA protein (MGP) — activated by Vitamin K2 — directly inhibits calcium crystal formation in arterial walls. Inactive MGP (from K2 deficiency) allows calcium to deposit in arteries — reducing flexibility and increasing cardiovascular risk. The Rotterdam Study found that populations with the highest K2 intake had 57% reduced cardiovascular mortality — one of the strongest dietary cardiovascular associations ever observed.
- Bacillus subtilis natto provides probiotic benefit throughout the digestive tract
- Produces unique dipicolinic acid with antimicrobial and anti-cancer properties
- Fermentation dramatically improves soy protein digestibility and isoflavone bioavailability
Why it works: B. subtilis natto produces spores that survive the acidic stomach environment and germinate in the small intestine — providing probiotic benefit throughout the entire digestive tract. Unlike Lactobacillus species that are mostly killed by stomach acid, Bacillus spores are highly resistant, making natto one of the more gut-penetrating probiotic foods.
- 8.6mg of iron per serving — one of the richest plant iron sources available
- Fermentation significantly improves iron bioavailability from soy
- Vitamin K2 supports red blood cell membrane integrity alongside iron's hemoglobin role
Why it works: Natto provides remarkable iron content for a plant food — comparable to red meat per serving. The fermentation process reduces phytic acid that would otherwise inhibit iron absorption, significantly improving the bioavailability of natto's iron compared to unfermented soy. This makes natto particularly valuable for plant-based diets.
- 17.7g of complete protein per serving — superior to tofu and comparable to meat
- Fermented isoflavones are more bioavailable than in tofu — providing stronger phytoestrogenic modulation
- Dipicolinic acid has anti-cancer properties unique to natto
Why it works: Natto's fermented isoflavones are in their aglycone form — directly absorbed without requiring gut bacterial conversion. This superior bioavailability produces more consistent and pronounced phytoestrogenic modulation for bone protection, hormonal balance and cancer prevention than unfermented soy products.
How to Use It
Recommended Products
Safety & Considerations
- Soy allergy requires complete avoidance
- Those on blood-thinning medications (warfarin) must NOT consume natto — the extremely high Vitamin K2 significantly interferes with warfarin dosing
- Nattokinase may interact with other anticoagulants — consult doctor if on any blood-thinning medication
- The flavor and texture are extremely unfamiliar to most Western palates — introduce gradually
- Generally safe for most people not on anticoagulants in normal dietary amounts
This content is for informational purposes only and is not intended as medical advice. Always consult a qualified healthcare professional before making changes to your diet, supplement use, or treatment plan.
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