Nattokinase and vitamin K2: what the evidence says and what I've seen
Nattokinase has measurable effects on blood pressure and fibrin activity. Natto, the food it comes from, is also the richest dietary source of vitamin K2. I have eaten it regularly for twelve years.
Straight to the point; nattokinase has measurable effects on cardiovascular markers. The research shows reductions in blood pressure, changes in fibrin activity, and, at higher doses, shifts in LDL, triglycerides, and arterial plaque. It is not a cure-all, but it produces real, observable changes.
Most people will come across nattokinase as a supplement. I came across it, unknowingly, through natto, the traditional Japanese fermented soybean food it comes from. Natto is not just a source of nattokinase. It is also, by a wide margin, the richest dietary source of vitamin K2 in its MK-7 form.
Natto and nattokinase are not the same thing. A nattokinase capsule gives you one isolated extract, usually measured in fibrinolytic units (FU). Natto gives you nattokinase, vitamin K2, protein, and the rest of the food matrix. In practice, I see them as related but not interchangeable.
Natto is typically eaten in small portions, around 40 grams at a time. Because vitamin K2 in the MK-7 form has a long half-life, roughly 2 to 3 days, I usually eat natto three times per week to maintain steady levels.
I have eaten natto consistently since 2013. I was 46, recovering from emergency surgery to remove an infected gallbladder, and trying to rebuild my health after the deleterious effects of conventional dietary advice. I came to natto through vitamin K2 research on heart health. I stayed because of what it did.
If you are looking into nattokinase benefits, the short version is this: it has measurable effects on blood pressure, fibrin activity, and some cardiovascular markers. If you are on blood thinners or have a bleeding disorder, speak to your doctor before adding natto or nattokinase.
What nattokinase is
Nattokinase is an enzyme produced during the fermentation of soybeans into natto by the bacterium Bacillus subtilis. It was identified in 1987 by Dr Hiroyuki Sumi at the University of Chicago, though natto itself has been consumed in Japan for centuries.
The enzyme breaks down fibrin, a protein involved in blood clot formation. Most of the clinical interest in nattokinase centres on that fibrinolytic activity and its downstream effects on circulation, blood pressure, and clot-related markers.
You can buy nattokinase as a supplement, usually dosed in fibrinolytic units (FU). You can also eat natto, and the two are not the same thing. Natto contains nattokinase, vitamin K2 in the MK-7 form, protein, and other compounds that a capsule does not include. A supplement gives you one isolated extract. The food gives you the whole matrix.
The cardiovascular evidence
A 2008 randomised controlled trial published in Hypertension Research tested nattokinase in people with pre-hypertension and stage 1 hypertension and found reductions in blood pressure. A 2023 systematic review and meta-analysis in Reviews in Cardiovascular Medicine combined multiple trials and reported consistent reductions in both systolic and diastolic blood pressure.
Blood pressure is the strongest part of the case for nattokinase. The data is clear enough to state plainly.
Beyond blood pressure, a 2022 clinical study published in Frontiers in Cardiovascular Medicine followed 1,062 participants taking nattokinase for 12 months. Total cholesterol, LDL cholesterol, and triglycerides all dropped significantly, and carotid artery plaque size decreased by 36 percent. That study used a dose of 10,800 FU per day, well above the 2,000 to 4,000 FU range used in most other trials, and the lower dose group in the same study showed no significant changes.
There is also research looking at fibrin-related markers such as D-dimer, which is relevant given nattokinase acts directly on fibrin.
Not all studies show benefit in every group. The Nattokinase Atherothrombotic Prevention Study (2021) found no effect on subclinical atherosclerosis in healthy, low-risk individuals. That tells you where nattokinase is less likely to do anything meaningful.
Nattokinase has consistent effects on blood pressure and fibrin activity. At higher doses, it may also influence other cardiovascular markers. The effects are real, but they are not universal and not a replacement for proper medical care.
Vitamin K2 and nattokinase
The search phrase vitamin K2 and nattokinase keeps rising because people are starting to recognise what natto contains. It is not just a source of nattokinase. It is, by a wide margin, the richest food source of vitamin K2 in MK-7 form.
K2 activates proteins that regulate calcium: osteocalcin, which supports bone mineralisation, and matrix GLA-protein, which helps keep calcium out of arteries and soft tissues. Without enough K2, it is possible to see both weakened bones and calcified arteries, which are often seen together.
When I eat natto, I get K2 and nattokinase together in one food. If I were supplementing, I would need separate capsules and assume they replicate the same effect. No trial has compared the whole food to isolated supplements head to head, so I cannot say one is superior. I chose the food because it made practical sense, and I stayed with it because the results held up.
One of the overlooked natto benefits is that simplicity. One food, multiple compounds, no stacking required.
What happened to my teeth
I came to natto looking for K2, initially for cardiovascular reasons. At the time, my health was already improving. I had removed grains, processed food, seed oils, and excess sugar. I was eating whole foods and animal-based protein.
But my teeth were still deteriorating. By my mid-forties the enamel at the gum line had worn away and grooves had formed. My dentist filled them and told me the deterioration could not be stopped.
He was wrong.
After I started eating natto regularly, the deterioration stopped. Over the following months, the enamel returned, the grooves smoothed over, and cavities disappeared.
Then I noticed a pattern. Acidic foods would strip the enamel. Consistent natto intake, around 40 grams per day, would see it recover within three to five days. That pattern held.
The mechanism aligns with what we know about K2 and mineral metabolism. Tooth enamel is largely mineral, and K2 activates proteins that help direct calcium where it is needed.
Context matters. This happened alongside a clean diet. Removing damaging inputs came first. Natto was not a fix on top of a poor diet.
I have not needed a dentist in over a decade. This is not a clinical trial. It is a long-term, repeatable personal observation that aligns with known biology.
Natto, supplements, and dosage
Clinical trials typically use 2,000 to 4,000 FU of nattokinase per day, though the 2022 Frontiers in Cardiovascular Medicine study suggests higher doses may be required for more significant changes.
For natto, dosing is less precise because it is a food.
If you are trying natto for the first time, the challenge is practical, not scientific. It has a strong smell and texture. If you cannot tolerate it, a nattokinase supplement combined with K2 MK-7 is a reasonable alternative.
My broader position is simple: fix the diet first. Natto or supplements come after that.
Nattokinase side effects and safety
Nattokinase has fibrinolytic activity. In simple terms, it thins the blood. That is where both its benefits and risks come from.
Anyone taking anticoagulants should not add nattokinase without medical advice. Natto adds complexity because it also contains vitamin K2, which interacts with certain medications.
The same applies to people with bleeding disorders or those preparing for surgery.
At standard doses, nattokinase has not shown significant adverse effects in clinical trials. If unsure, speak to your doctor.
Where natto fits
Natto is not a miracle food, (but has been miraculous for my dental health), and nattokinase is not a miracle supplement. Both are useful, within limits.
The benefits I consider well supported are lower blood pressure and reduced fibrin activity. The advantage of natto over a supplement is that it also provides vitamin K2.
The reason I keep it in my diet is simpler than the research. It produced consistent, observable results over more than a decade.
It sits within a broader approach. Remove what is doing harm. Build around whole foods. Then add in things that support function.
Natto is one of those things. Not the whole picture, but a solid piece of it.
