Source Naturals Nattokinase 50mg (SN1823) delivers a purified, bioactive systemic enzyme isolated from traditional Japanese fermented soybean (natto). Engineered to support cardiovascular dynamics, nattokinase works systemically to assist the body's natural fibrinolytic clearing mechanisms, degrade excess cross-linked fibrin, and promote smooth, healthy blood viscosity without unnecessary synthetic fillers.
What Is Nattokinase? The Science of Fermented Fibrinolytic Enzymes
Nattokinase is a 275-amino acid alkaline serine protease with an approximate molecular weight of 27.7 kDa, derived from the fermentation of non-GMO soybeans by the probiotic bacterium Bacillus subtilis var. natto. First identified in 1980 by Dr. Hiroyuki Sumi at the University of Chicago and Miyazaki Medical College, nattokinase was discovered when fermented natto was placed onto an artificial fibrin thrombus in a Petri dish; the enzyme cleaved the clot completely within 18 hours, demonstrating a fibrin-degrading potential far exceeding other conventional enzymes (Sumi et al., 1987).
Unlike typical digestive enzymes that break down proteins inside the gastrointestinal lumen, nattokinase is a systemic enzyme. When taken on an empty stomach, it passes through the intestinal mucosal epithelium intact into the bloodstream, where it exerts direct proteolytic activity against intravascular fibrin build-up and promotes fluid shear dynamics across capillary beds.
Mechanism of Action: How Nattokinase Supports Arterial & Venous Blood Flow
The circulatory system relies on a delicate homeostatic balance between coagulation (clot formation via fibrin) and fibrinolysis (clot breakdown via plasmin). As we age, vascular endothelial inflammation, elevated stress, and sedentary lifestyles can elevate clotting proteins and suppress our natural clearing enzymes. Research confirms that Nattokinase 50mg operates through four distinct cardiovascular mechanisms:
1. Direct Cleavage of Cross-Linked Fibrin
Nattokinase directly mimics plasmin—the body's only endogenous fibrinolytic enzyme. It cleaves cross-linked fibrin strands within microscopic deposits, breaking them down into soluble fibrin degradation products (FDPs) and D-dimers without destroying essential clotting factors during minor tissue repair.
2. Cleavage of Plasminogen Activator Inhibitor-1 (PAI-1)
Plasminogen Activator Inhibitor-1 (PAI-1) acts as the primary "brake" on the body's natural clot-dissolving machinery. Elevated PAI-1 levels paralyze tissue plasminogen activator (t-PA), allowing fibrin to accumulate. Clinical studies demonstrate that nattokinase proteolytically degrades PAI-1, releasing this inhibition and allowing natural fibrinolysis to resume unimpeded (Urano et al., 2001).
3. Upregulation of Tissue Plasminogen Activator (t-PA) & Urokinase
In addition to clearing inhibitors, nattokinase stimulates vascular endothelial cells to release endogenous tissue plasminogen activator (t-PA) and facilitates the conversion of inactive pro-urokinase into active urokinase (u-PA). This triggers a self-sustaining wave of natural plasmin activation directly along the vessel lumen.
4. Reduction of Whole Blood Viscosity & Red Cell Aggregation
By breaking down excess circulating fibrinogen and preventing red blood cells from stacking into rigid chains (rouleaux formation), nattokinase lowers whole blood viscosity. Decreased vascular friction improves microvascular capillary perfusion, peripheral blood flow to extremities, and healthy arterial wall elasticity.
Potency Breakdown: Why Fibrinolytic Units (FU) Matter More Than Milligrams
When evaluating nattokinase supplements, weight (milligrams) does not dictate potency—enzymatic activity does. Enzyme potency is measured in Fibrinolytic Units (FU), which represent the enzyme's quantifiable laboratory ability to hydrolyze and dissolve a calibrated mass of fibrin substrate over time.
Standard Clinical Target: Most clinical research on cardiovascular clearance and blood pressure stabilization validates daily dosing between 2,000 FU to 4,000 FU.
Source Naturals SN1823 Formulation: Formulated with premium concentrated nattokinase, providing targeted, flexible enzyme delivery. A standard daily intake of 1 to 2 softgels up to three times daily delivers reliable, standardized fibrinolytic units (1,440 FU to 2,000+ FU per therapeutic day), allowing users to adjust their intake based on their healthcare provider's recommendations.
Vitamin K2 Removal: Whole food natto is naturally rich in Vitamin K2 (menaquinone-7), which supports clotting cascades. High-grade clinical nattokinase extracts, such as those selected by Source Naturals, undergo specialized molecular isolation to remove Vitamin K2, ensuring pure fibrinolytic action that will not conflict with baseline vascular clearing.
Clinical Research & Scientific Citations
Nattokinase has been the subject of extensive international human clinical trials, animal studies, and pharmacodynamic reviews:
Antihypertensive & Vascular Resistance Effects:
In an 8-week randomized, double-blind, placebo-controlled human clinical trial involving 86 subjects aged 20 to 80 years, daily supplementation with 2,000 FU of nattokinase resulted in a statistically significant reduction in both systolic blood pressure (-5.55 mmHg) and diastolic blood pressure (-2.84 mmHg) compared to placebo (Kim et al., 2008, Hypertension Research).
Deep Vein & Microcirculatory Flight Study:
The landmark FLIGHT trial evaluated 186 passengers on long-haul flights (7 to 8 hours) at high risk for deep vein thrombosis (DVT) and edema. Patients administered an oral enzyme combination containing nattokinase and pinokinase prior to flight demonstrated zero thrombotic events and significantly reduced lower-leg edema, whereas the placebo control group experienced 7 venous events (5 deep, 2 superficial) and measurable fluid pooling (Cesarone et al., 2003, Angiology).
Comprehensive Review on Fibrinolytic Dynamics:
A pharmacologic review published in Biomarker Insights demonstrated that nattokinase possesses potent multi-pathway activity: accelerating plasma fibrin breakdown, extending prothrombin time (PT) and activated partial thromboplastin time (APTT) within safe biological margins, and degrading vascular atherosclerotic plaques without producing hemorrhagic side effects (Weng et al., 2017).
Source Naturals adheres strictly to Good Manufacturing Practices (cGMP) and third-party laboratory verification for identity, potency, and purity.
Supplement Facts
Serving Size: 2 Softgels • Servings Per Container: 30
Active Ingredients
Amount Per Serving
% Daily Value
Nattokinase
(standardized providing ~1,440 to 2,000 Fibrinolytic Units [FU] of active systemic enzyme)
72 mg to 100 mg*
†
† Daily Value not established.
*Batch potencies may vary based on standardized FU activity assays (delivering 50mg active nattokinase equivalent per single softgel).
Complete Ingredients:
Active Ingredient: Pure Nattokinase (from fermented, non-GMO soybean extract via Bacillus subtilis var. natto).
Other Ingredients (Excipients): Soybean oil, gelatin, vegetable glycerin, purified water, beeswax, glycerin fatty acid ester, and soybean lecithin.
Allergen Declaration: Contains Soy.
Does NOT Contain: Yeast, dairy, egg, gluten, corn, wheat, starch, sugar, salt, preservatives, or artificial colors, flavors, or fragrances.
Suggested Use & Pharmacokinetic Administration
To achieve maximum systemic absorption and biological activity, nattokinase must be taken correctly:
Take on an Empty Stomach: Consume 1 to 2 softgels three times daily, at least 45 minutes before meals or 2 hours after eating, with a full 8-ounce glass of pure water.
Why the Empty Stomach Is Essential: When ingested with food, nattokinase acts as a general protease, spending its catalytic energy digesting dietary proteins in the stomach. When consumed without food, it rapidly traverses the acidic stomach environment and enters the duodenum intact, allowing full systemic absorption into plasma.
Consistent Timing: Plasma fibrinolytic activity peaks approximately 2 to 4 hours post-ingestion, with active breakdown metabolites circulating for 8 to 12 hours. Evening dosing (before bed) is frequently recommended by practitioners because nocturnal blood flow is naturally more sluggish and endogenous fibrinogen concentrations elevate overnight.
Safety Information, Contraindications & Drug Interactions
Important Medical Advisory: Nattokinase affects systemic coagulation parameters. Consult a board-certified physician before incorporating this supplement into your daily regimen, especially if you are managing chronic cardiovascular disease.
Prescription Anticoagulant / Antiplatelet Medications: Do NOT take nattokinase in conjunction with prescription blood thinners such as Warfarin (Coumadin), Heparin, Clopidogrel (Plavix), Apixaban (Eliquis), Rivaroxaban (Xarelto), or daily therapeutic Aspirin unless directly managed and monitored by a hematologist or cardiologist. Combining systemic enzymes with blood-thinning drugs can increase the risk of unexpected bruising or bleeding.
Bleeding Disorders: Contraindicated in individuals diagnosed with active peptic ulcers, hemophilia, von Willebrand disease, recent intracranial hemorrhage, or any other coagulopathy.
Pre-Operative Protocol: Discontinue use of nattokinase at least 14 days prior to any scheduled surgical or dental procedure to prevent prolonged operative bleeding times.
Pregnancy & Lactation: Do not use if you are pregnant, planning to become pregnant, or nursing, as clinical safety profiles have not been established in these populations.
Frequently Asked Questions About Nattokinase 50mg
What is the difference between Nattokinase milligrams (mg) and Fibrinolytic Units (FU)?
Milligrams (mg) measure the physical weight of the extract powder or softgel contents, whereas Fibrinolytic Units (FU) measure the enzymatic activity—specifically the enzyme's laboratory capacity to dissolve fibrin clots. A 50mg softgel that provides high enzymatic activity is more biologically potent than a 100mg supplement containing poorly standardized raw powder. Always check for standardized FU per dose.
How quickly does Nattokinase begin working in the body?
Pharmacokinetic studies show that nattokinase enters systemic circulation and increases plasma fibrinolytic activity within 2 to 4 hours after oral ingestion on an empty stomach. Its biochemical effects on blood viscosity and fibrin clearance can remain active for 8 to 12 hours. For long-term arterial flexibility and blood pressure support, clinical trials typically evaluate results after 8 to 12 weeks of daily, consistent use.
Does Source Naturals Nattokinase 50mg contain Vitamin K2?
While traditional whole fermented food natto contains substantial amounts of Vitamin K2 (menaquinone-7), purified nattokinase dietary supplements undergo specialized filtration to remove Vitamin K. This ensures that the supplement provides targeted fibrinolytic activity without providing the coagulant-promoting cofactors associated with high-dose Vitamin K intake.
Can I take Nattokinase with Serrapeptase or Lumbrokinase?
Yes, many cardiovascular and functional medicine practitioners combine nattokinase with serrapeptase for synergistic systemic enzyme benefits. Nattokinase primarily targets fibrin within the blood vessels, while serrapeptase specializes in clearing dead cellular debris and cellular swelling throughout soft tissue. However, combining nattokinase with lumbrokinase (an exceptionally potent earthworm-derived enzyme) requires professional supervision, as stacking multiple strong fibrinolytic agents significantly amplifies blood-thinning actions.
Why must Nattokinase be taken strictly on an empty stomach?
Nattokinase is an active protease. If you consume it with meals or snacks, the enzyme will spend its catalytic power digesting dietary proteins in your stomach (similar to pepsin or bromelain). When taken on an empty stomach with 8 oz of pure water (at least 45 minutes before eating or 2 hours after), the enzyme passes into the intestines undamaged and absorbs directly into your bloodstream to work on vascular circulation.
Is Source Naturals Nattokinase safe for people with soy allergies?
Because nattokinase is derived from soybeans fermented by Bacillus subtilis var. natto, and the softgel carrier contains soybean oil and soybean lecithin, this product contains soy and is not recommended for individuals with severe, IgE-mediated soy allergies.
