Nattokinase

Nattokinase is a fibrinolytic enzyme extracted from natto, a traditional Japanese fermented soybean food produced by Bacillus subtilis. It works by breaking down fibrin and blood clots through its proteolytic activity, demonstrating significant thrombolytic and antithrombotic properties. Primarily used as a dietary supplement for cardiovascular health, it has shown benefits in managing atherosclerosis, reducing blood pressure, and improving circulation.

Overview

Nattokinase (NK, subtilisin NAT, EC 3.4.21.62) is a 275-amino-acid serine protease produced by the bacterium Bacillus subtilis var. natto during the fermentation of soybeans to produce natto — a traditional Japanese food consumed for over 1,000 years. The enzyme was discovered in 1987 by Dr. Hiroyuki Sumi at the University of Chicago, who observed that natto could dissolve artificial fibrin clots placed on a petri dish with remarkable efficiency. Nattokinase demonstrates direct fibrinolytic activity by cleaving cross-linked fibrin, and also enhances endogenous fibrinolysis through multiple indirect mechanisms: it converts plasminogen to plasmin, increases tissue plasminogen activator (tPA) activity, and degrades plasminogen activator inhibitor-1 (PAI-1) — the primary physiological inhibitor of fibrinolysis. This multimodal thrombolytic profile distinguishes nattokinase from pharmaceutical thrombolytics that typically act through a single mechanism.

Clinical evidence supporting nattokinase spans several cardiovascular domains. Randomized controlled trials have demonstrated significant reductions in blood pressure (both systolic and diastolic) in hypertensive subjects, with a 2016 meta-analysis reporting mean reductions of approximately 5.5 mmHg systolic and 2.8 mmHg diastolic. The antihypertensive mechanism involves inhibition of angiotensin-converting enzyme (ACE) and reduction of blood viscosity. For atherosclerosis, a notable 26-week clinical trial showed that nattokinase supplementation (6,000 FU/day) significantly reduced carotid artery plaque size by 37% compared to baseline, while the statin-treated control group showed 11.5% reduction. Additional cardiovascular benefits include reduction of Factor VII and Factor VIII clotting factors, decreased blood viscosity, improved erythrocyte aggregation, and reduction of elevated fibrinogen levels. Nattokinase also demonstrates activity against amyloid fibrils in vitro, generating interest in neurodegenerative disease research.

Nattokinase is standardized by fibrinolytic activity measured in fibrin units (FU), with typical supplemental doses of 2,000–4,000 FU (100–200 mg) daily, taken on an empty stomach for optimal absorption. The enzyme survives gastric transit and is absorbed intact into the bloodstream, with fibrinolytic activity detectable in plasma within 2–4 hours of oral administration. Important safety considerations include the potential for enhanced bleeding when combined with anticoagulant medications (warfarin, heparin, direct oral anticoagulants) or antiplatelet agents (aspirin, clopidogrel), and nattokinase should be discontinued 2 weeks before surgery. It pairs well with other cardiovascular support compounds such as omega-3 fatty acids, CoQ10, and garlic extract in comprehensive cardiovascular health protocols. Side effects are uncommon at standard doses.

Mechanism of Action

Nattokinase is a serine protease (EC 3.4.21.62) produced by Bacillus subtilis var. natto during soybean fermentation. Its primary mechanism of action involves direct fibrinolytic activity, where it cleaves cross-linked fibrin polymers in blood clots through hydrolysis of peptide bonds at specific Arg-Xaa sites. Unlike pharmaceutical thrombolytics that require plasminogen activation, nattokinase possesses both direct fibrinolytic activity and indirect thrombolytic mechanisms. Indirectly, it enhances endogenous fibrinolysis by cleaving and inactivating plasminogen activator inhibitor-1 (PAI-1), thereby increasing tissue-type plasminogen activator (t-PA) activity and promoting conversion of plasminogen to plasmin.

Nattokinase also degrades fibrinogen directly, reducing substrate availability for new clot formation. It decreases blood viscosity by reducing plasma fibrinogen levels and red blood cell aggregation. The enzyme inhibits platelet aggregation by suppressing thromboxane A2 (TXA2) formation and enhancing endothelial prostacyclin (PGI2) production, shifting the TXA2/PGI2 balance toward an antithrombotic state. Additionally, nattokinase has been shown to reduce factor VII and factor VIII coagulation activity, further attenuating the coagulation cascade. It demonstrates antihypertensive properties by inhibiting angiotensin-converting enzyme (ACE), reducing angiotensin II-mediated vasoconstriction.

Therapeutically, nattokinase is used as a cardiovascular protective supplement due to its multi-target antithrombotic, fibrinolytic, and antihypertensive activities. Clinical studies have demonstrated reductions in blood pressure, fibrinogen levels, and factor VIII activity in human subjects. Its oral bioavailability, sustained duration of action (8-12 hours), and favorable safety profile distinguish it from injectable thrombolytics. Nattokinase shows particular promise for prevention of deep vein thrombosis, atherosclerotic plaque stabilization, and as an adjunct in cardiovascular risk reduction.

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Research

Safety Profile

The primary risk is an increased chance of bleeding due to its blood-thinning properties. It is contraindicated for individuals with bleeding disorders, active ulcers, or those scheduled for surgery. People taking anticoagulant medications or with low blood pressure should consult a healthcare provider before use.

Pharmacokinetic Profile