Nattokinase and vitamin K2 come out of 1 pot of fermented soybeans, and they are sold together constantly. They also pull in 2 opposite directions on clotting.
That contradiction is the whole reason this page exists.
Quick Answer: Should You Take Nattokinase With Vitamin K2?
They are 2 different molecules from the same food. Nattokinase is an enzyme that breaks fibrin down; vitamin K2 is a vitamin the body needs to build clotting factors. Combination products exist because natto contains both, not because a trial tested the pair. If you take warfarin, vitamin K2 is the specific problem, because warfarin works by blocking vitamin K.
Key Takeaways
- Both come from natto, but they are 2 entirely different molecules.
- 1 breaks fibrin down, the other helps build clotting factors instead.
- 0 trials have tested the 2 together as a deliberate combination.
- Extra K2 opposes warfarin, the 1 drug that works by blocking vitamin K.
- We sell 0 vitamin K2 products, so nothing here is selling you one.
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Two Molecules, One Food
The confusion is understandable, because both names appear on the same bottles and both trace back to the same Japanese breakfast dish.
| Nattokinase | Vitamin K2 (MK-7) | |
|---|---|---|
| What it is | An enzyme | A fat-soluble vitamin |
| Made by | Bacillus subtilis during fermentation | The same bacteria, as a by-product |
| Effect on clotting | Breaks fibrin down | Helps build clotting factors |
| Measured in | Fibrin units, FU | Micrograms |
| In our capsule | 2000 FU | None |
What the enzyme half is and does is set out in what the enzyme is.
Why They Look Contradictory
Read the table above and the pairing looks like a mistake. It is worth being precise about why it is not quite one.
- Nattokinase acts on: Fibrin that has already formed.
- Vitamin K2 acts on: Proteins that direct calcium in bone and artery walls.
- Where they overlap: Vitamin K also drives clotting-factor production.
- What has been tested: 0 trials of the deliberate combination.
Vitamin K2 is mostly studied for arterial calcification and bone, not as a clotting agent. The overlap with clotting is real but it is not what people buy K2 for.
The enzyme half has been measured directly in people, including a single 2000 FU dose in 12 healthy men.[3]A single-dose of oral nattokinase potentiates thrombolysis and anti-coagulation profiles — Scientific Reports (2016) View source Nothing comparable exists for the pairing.
Why Combination Products Exist
The honest answer is provenance rather than pharmacology.
- Reason 1: Natto naturally contains both, so the pairing feels native.
- Reason 2: Both are marketed for arteries, from different angles.
- Reason 3: 2 actives on a label reads as better value.
- Not a reason: Any trial showing the pair beats either alone.
A 2024 meta-analysis of randomized trials looked at nattokinase and cardiovascular risk factors and did not evaluate it as half of a K2 pairing.[1]Nattokinase Supplementation and Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials — Reviews in Cardiovascular Medicine (2024) View source Every trial in this literature tested the enzyme, not the duo.
The Warfarin Problem, Specifically
This is the part that matters most, and it is a different problem from the one nattokinase itself creates.
- How warfarin works: By blocking vitamin K recycling.
- What extra K2 does: Works directly against it.
- What nattokinase does: Pushes the other way, raising bleeding risk.
- A product with both: Interferes at 2 points at once.
A published case describes a patient who stopped warfarin and took nattokinase instead after a mechanical aortic valve replacement.[2]Consequence of patient substitution of nattokinase for warfarin after aortic valve replacement with a mechanical prosthesis — Proceedings (Baylor University Medical Center) (2015) View source The full set of interaction rules is in why warfarin changes everything.
What We Actually Sell
Worth saying plainly, since this page ranks for a combination we do not stock.
- Our capsule contains: 2000 FU nattokinase.
- Vitamin K2 in it: None.
- Also in it: A 1000 mg proprietary garlic and turmeric blend.
- K2 products we sell: 0.
If you want the enzyme without the vitamin, the capsule form is exactly that. If you want K2, you will need to buy it elsewhere, and you should tell your prescriber either way.
How to Decide
Three questions settle it faster than any comparison table.
- On warfarin? Then neither, without your prescriber.
- Want the enzyme? A single-ingredient product tells you the FU.
- Want K2 for bone? That is a separate decision from this one.
- Want both anyway? Ask specifically about the clotting overlap.
Where the food itself sits in all this is in the food it comes from.
Do Not Start Either, 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
Should I take nattokinase with vitamin K2? +
There are 0 trials of the deliberate combination. They come from the same food but they act on clotting in 2 opposite directions.
Why are nattokinase and K2 sold together? +
Because natto naturally contains both, and 2 actives read better on a label. It is provenance, not a trial result.
Does vitamin K2 cancel out nattokinase? +
Not exactly, but they oppose each other on clotting. 0 studies have measured what the net effect is in a person.
Can I take K2 with warfarin? +
Not without your prescriber. Warfarin works by blocking vitamin K, so extra K2 works directly against the 1 drug you are relying on.
Is MK-7 the same as vitamin K2? +
MK-7 is 1 form of vitamin K2, and it is the form found in natto. It is not the same molecule as nattokinase.
Does your nattokinase contain vitamin K2? +
No. Our capsule has 2000 FU of nattokinase and a 1000 mg garlic and turmeric blend, with 0 added vitamin K2.
Which is better for arteries? +
They are studied for different things, so there is no single winner. K2 research focuses on calcification, and the 10 nattokinase trials focus on clotting markers.
Can I get both from eating natto? +
Yes, natto contains both of the 2 naturally. What it does not give you is a standardised number of fibrin units per serving.
Do I need K2 if I take nattokinase? +
No. There is no requirement, and 0 evidence that the enzyme creates a vitamin K2 need.
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