Natto the food is searched 18100 times a month, which is more than the supplement itself. The 2 are not interchangeable in the way most people assume.
The food gives you things the capsule does not, and the capsule gives you 1 thing the food cannot.
Quick Answer: Natto Food or Nattokinase Supplement?
Natto is the whole fermented soybean dish; nattokinase is 1 enzyme extracted from it. The food also supplies vitamin K2, fibre, protein and live Bacillus subtilis, none of which a nattokinase capsule contains. What the food cannot give you is a standardised dose, because fibrin units per serving vary with the batch. The capsule exists to fix that 1 problem.
Key Takeaways
- Natto is the food; nattokinase is 1 enzyme taken out of it.
- The food also carries 4 extras: vitamin K2, fibre, protein and bacteria.
- 1 serving of natto has no standardised fibrin unit count.
- Our capsule delivers a fixed 2000 FU, which the food cannot.
- 0 trials have compared eating natto against taking the enzyme.
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What Natto Actually Is
Before comparing them it helps to be concrete about the food, which most people outside Japan have never eaten.
- What it is: Boiled soybeans fermented with Bacillus subtilis.
- Texture: Sticky and stringy, which is the usual sticking point.
- Eaten as: A breakfast dish, often over rice.
- Contains: The enzyme, vitamin K2, fibre, protein and live bacteria.
The enzyme half is the part sold in capsules, and it is described in our guide to the enzyme.
What a Serving Delivers
This is where the comparison stops being about preference and starts being about numbers.
| A serving of natto | One of our capsules | |
|---|---|---|
| Nattokinase | Present, amount varies by batch | 2000 FU, fixed |
| Vitamin K2 | Yes, naturally | None |
| Fibre and protein | Yes | None |
| Live Bacillus subtilis | Yes | None |
| Standardised dose | No | Yes |
Fermentation is a biological process rather than a manufacturing one, so 2 batches of natto do not carry identical enzyme activity. That is the honest case for a capsule.
The Vitamin K2 Difference
This is the difference most likely to matter medically, and it usually gets skipped.
- Natto is: One of the richest known food sources of vitamin K2.
- Most enzyme capsules are: Purified, so K2 is largely absent.
- Why it matters: Warfarin works by blocking vitamin K.
- The consequence: Eating natto on warfarin is a specific problem.
Anyone taking warfarin is usually told to keep vitamin K intake steady rather than variable, and that is a separate issue from the enzyme. The pairing is unpicked in nattokinase and vitamin K2.
Is the Food Safer
Broadly yes, because it has been eaten for centuries, but broadly is not the same as always.
- In its favour: Centuries of daily consumption in Japan.
- Against it: Soy and natto allergy, with 1 published anaphylaxis case.
- Extremely rare: 1 case of meningitis from the natto strain itself.
- Shared with capsules: The vitamin K2 issue for anyone on warfarin.
The meningitis case involved a 67-year-old woman who ate natto daily, with the strain confirmed by sequencing as B. subtilis var. natto.[1]Bacterial Meningitis Caused by Bacillus subtilis var. natto — Internal Medicine (2023) View source She recovered on vancomycin. One case across a national diet is about as rare as a risk gets, and it is included here because leaving it out would be selective.
What the Trials Used
Worth knowing before deciding, because the research was not done on breakfast.
- What trials gave: Purified enzyme at measured fibrin units.
- Trials feeding natto instead: Effectively 0 for these endpoints.
- The anchor dose: 2000 FU, in a 12-person crossover study.
- What that means: Capsule evidence does not transfer to servings.
The single-dose crossover trial administered 2000 FU of purified enzyme and measured clotting and fibrinolysis parameters.[2]A single-dose of oral nattokinase potentiates thrombolysis and anti-coagulation profiles — Scientific Reports (2016) View source Nobody has run that study with a bowl of natto.
What those fibrin units mean on a label is unpacked in dosage and FU explained.
Which to Choose
It depends on what you actually want out of it, and the 2 goals are genuinely different.
- Want a food: Eat natto, and enjoy the K2 and fibre with it.
- Want a measured amount: A capsule is the only way to get 1.
- On warfarin: Neither, without your prescriber.
- Allergic to soy: Neither, and that includes the purified enzyme.
If the measured amount is the point, our nattokinase bottle carries 2000 FU per capsule, which a serving cannot promise.
- Food gives you: K2, fibre, protein and live bacteria.
- Capsule gives you: 1 fixed number of fibrin units.
- Trials used: The capsule, in all 10 of them.
- Neither is right if: You take 1 of the blood thinners.
The 2024 meta-analysis pooled trials of the supplement rather than of the food, which is why its conclusions belong to capsules.[3]Nattokinase Supplementation and Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials — Reviews in Cardiovascular Medicine (2024) View source
Choose Neither, and Speak to a Clinician First, If
- You take warfarin, a DOAC, aspirin, clopidogrel or any other anticoagulant or antiplatelet
- You have a mechanical heart valve, a stent or any implanted cardiac device
- You have a bleeding disorder such as haemophilia, or a history of haemorrhagic stroke
- You have surgery or a dental procedure booked within the next 2 weeks
- You are pregnant, breastfeeding, or allergic to soy or natto
Frequently Asked Questions
Is eating natto as good as taking nattokinase? +
It gives you more, including vitamin K2 and fibre, but 0 guarantee of how many fibrin units are in a serving.
How much nattokinase is in a serving of natto? +
It varies by batch, because fermentation is biological. That is the 1 thing a capsule fixes.
Does natto contain vitamin K2? +
Yes, and it is 1 of the richest known food sources. Most purified enzyme capsules contain none.
Can I eat natto on warfarin? +
Ask your prescriber first. Natto is very high in vitamin K2, and warfarin works by blocking vitamin K.
What does natto taste like? +
Strong, savoury and ammonia-like, with a sticky stringy texture. It is 1 of the more divisive foods in the world.
Is natto safe to eat every day? +
It is eaten daily across Japan. 1 published case of meningitis from the natto strain exists, which is about as rare as a food risk gets.
Do capsules contain live bacteria? +
No. Purified capsules contain the 1 enzyme, not the live Bacillus subtilis found in the food.
Which has more evidence behind it? +
The capsule. All 10 clinical trials used measured enzyme, and effectively 0 fed people natto for these endpoints.
Can I make natto at home? +
You can, with a starter culture. It will still give you 0 idea of the fibrin units per serving.
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