High-Potency Systemic Enzyme Support for Healthy Blood Flow, Vascular Elasticity, and Heart Function
If you are looking for advanced cardiovascular support, healthy circulation is the place to start. Every organ, muscle, and tissue in your body relies on smooth blood flow to deliver fresh oxygen and nutrients while clearing away cellular waste. Source Naturals Nattokinase NSK-SD® 200 mg delivers a concentrated, clinically researched systemic enzyme derived from natto—a traditional Japanese fermented soybean food prized for centuries for its cardiovascular longevity benefits.
Unlike standard 100 mg formulas, this double-strength capsule supplies an impressive 4,000 Fibrinolytic Units (FU) of genuine, non-GMO NSK-SD® per serving. Patented and standardized by Japan Bio Science Laboratories (JBSL), this pure extract undergoes a proprietary process that removes virtually all Vitamin K2, ensuring pure enzymatic activity that supports your body's natural circulatory clearing pathways without interfering with clot-balancing mechanisms.
Key Highlights at a Glance:
✓Double Potency: 200 mg providing 4,000 FU per single capsule.
✓Authentic NSK-SD®: The gold-standard, clinically studied nattokinase extract.
✓Vitamin K2 Removed: Less than 0.1 ppm Vitamin K ensures targeted enzymatic action.
✓Systemic Fibrin Support: Cleanses micro-capillaries and supports healthy arterial elasticity.
✓Clean Formulation: Non-GMO, free of gluten, dairy, yeast, artificial colors, and preservatives.
How Nattokinase Works in Plain English: Breaking Down Fibrin
To understand why nattokinase is so widely recommended by integrative cardiologists, think of your circulatory system as a vast network of highways. Over time, physical stress, natural aging, and metabolic factors can cause tiny internal roadblocks that make blood flow thicker and less efficient.
A key player in this process is a mesh-like structural protein called fibrin. In normal circumstances, your body creates fibrin like a biological net to stop bleeding when you have an injury. Once healing is complete, your body uses natural enzymes (primarily plasmin) to dissolve that net away.
However, as we age, natural plasmin production declines, while fibrin levels often rise. When excess fibrin lingers inside blood vessels, blood becomes thicker (increased blood viscosity), putting unnecessary strain on the heart and making arteries less pliable.
The Dual-Action Advantage of Nattokinase
Nattokinase acts like microscopic biological shears inside the bloodstream via two distinct mechanisms:
Direct Action: It directly breaks down excess cross-linked fibrin webs, helping to keep blood moving freely through narrow capillaries.
Indirect Activation: It supports your body's internal clearing mechanisms by prompting the release of tissue plasminogen activator (t-PA), which turns on your natural reserves of plasmin.
Why NSK-SD® Is the Clinically Recognized Gold Standard
Not all nattokinase supplements are manufactured equally. Raw natto food contains unpredictable enzyme levels and high concentrations of Vitamin K2. While Vitamin K2 is beneficial for bone health, it acts as a primary building block for blood-clotting factors in the liver, directly working against the circulatory clearing action you want from a fibrinolytic enzyme.
Source Naturals specifically partners with Japan Bio Science Laboratories (JBSL) to utilize NSK-SD® (Natural Super Kinase - Sprayed Dried). Here is why NSK-SD® stands head and shoulders above generic alternatives:
Patented Vitamin K2 Removal: Through JBSL's patented purification technology, Vitamin K2 is reduced to less than 0.1 parts per million (ppm), eliminating unwanted coagulation counter-effects.
Verified Bacterial Lineage: It is fermented exclusively using a proprietary, non-GMO strain of Bacillus subtilis var. natto, authenticated by four distinct identity and DNA sequencing tests.
Standardized Potency (FU): Enzyme activity is measured in Fibrinolytic Units (FU) rather than mere milligram weight. Every capsule of Source Naturals 200 mg delivers an exact, laboratory-verified 4,000 FU.
Extensive Safety Documentation: NSK-SD® has undergone over 30 safety and efficacy evaluations, including human clinical trials, animal studies, and recognized safety reviews overseen by global standards bodies.
Clinical Research & Scientific Evidence
Since its initial discovery by Dr. Hiroyuki Sumi in 1980 at Chicago University Medical School, nattokinase has become one of the most thoroughly investigated natural cardiovascular compounds in medical literature. Human clinical trials demonstrate tangible benefits for blood pressure regulation, circulation, and vascular health:
1. Healthy Blood Pressure Support
In a randomized, double-blind, placebo-controlled clinical trial published in Hypertension Research, 86 subjects aged 20 to 80 years with elevated blood pressure were administered nattokinase daily for 8 weeks. Participants receiving nattokinase demonstrated statistically significant reductions in both systolic and diastolic blood pressure compared to the placebo group. Researchers also observed a noticeable decrease in plasma renin activity, indicating that nattokinase helps calm kidney-mediated vascular constriction signals.
Citation: Kim, J. Y., et al. (2008). "Effects of nattokinase on blood pressure: a randomized, controlled trial." Hypertension Research, 31(8), 1583–1588. [PMID: 18971533]
2. Rapid & Sustained Circulatory Action
A landmark human crossover study published in Scientific Reports evaluated the direct fibrinolytic effects of a single oral dose of NSK-SD® in healthy young men. Blood analysis at 2, 4, 6, and 8 hours following administration revealed measurable increases in fibrin/fibrinogen degradation products (FDP) and D-dimer concentrations, alongside enhanced antithrombin activity. Crucially, the circulatory support of oral nattokinase remained active for over 8 hours post-ingestion.
Citation: Kurosawa, Y., et al. (2015). "A single-dose of oral nattokinase potentiates thrombolysis and anti-coagulation profiles." Scientific Reports, 5, 11601. [PMID: 26109079]
3. Endothelial Protection & Vascular Markers
A multicenter North American randomized, double-blind, placebo-controlled trial evaluated adults receiving nattokinase over 8 weeks. Supplementation was associated not only with healthy blood pressure stabilization but also with a meaningful decline in von Willebrand factor (vWF)—a key circulatory protein linked to endothelial stress and abnormal platelet adhesion.
Citation: Jensen, G. S., et al. (2016). "Consumption of nattokinase is associated with reduced blood pressure and von Willebrand factor, a cardiovascular risk marker." Integrated Blood Pressure Control, 9, 95–104. [PMID: 27785095]
4. Long-Term Arterial Health & Higher-Dose Protocols
In a massive clinical study involving 1,062 participants published in Frontiers in Cardiovascular Medicine, researchers examined long-term nattokinase protocols on carotid arterial thickness and lipid profiles over 12 months. The trial confirmed that consistent daily nattokinase intake meaningfully supported arterial wall flexibility and normal lipid management, demonstrating that higher daily activity levels (above 3,600 FU) were particularly effective for ongoing vascular maintenance.
Citation: Chen, H., et al. (2022). "Effective management of atherosclerosis progress and hyperlipidemia with nattokinase: A clinical study with 1,062 participants." Frontiers in Cardiovascular Medicine, 9, 964977. [PMID: 36172225]
100 mg (2,000 FU) vs. 200 mg (4,000 FU): Choosing Your Potency
Most entry-level nattokinase products on the market supply 100 mg delivering 2,000 FU per serving. While 2,000 FU is well-suited for general baseline maintenance, Source Naturals developed this 200 mg (4,000 FU) formulation for individuals seeking intensified cardiovascular care without having to swallow multiple capsules per day.
Feature
Standard Formulas (100 mg)
Source Naturals NSK-SD® (200 mg)
Enzymatic Potency
2,000 FU per capsule
4,000 FU per capsule
Target User
General daily wellness
Targeted circulation, blood pressure, and arterial support
Capsules Needed Daily
2 to 3 capsules
1 capsule (up to 3 as recommended)
Vitamin K2 Content
Variable (often unverified)
Guaranteed < 0.1 ppm removed
How to Take for Maximum Absorption: The Empty Stomach Rule
Because nattokinase is a systemic proteolytic enzyme, timing makes all the difference in how your body utilizes it:
Why an Empty Stomach Is Essential:
If you take nattokinase with a meal, your stomach will treat it as a digestive enzyme. It will get busy breaking down the dietary proteins in your chicken, steak, or tofu instead of entering your circulation. When taken on an empty stomach (at least 30 to 45 minutes before eating, or 2 hours after a meal) with 8 ounces of water, the enzyme bypasses active digestion and absorbs intact through the intestinal wall directly into your bloodstream.
Suggested Retail Routine: Take 1 capsule once to three times daily on an empty stomach with a full glass of water, or as directed by your healthcare professional. Many individuals prefer taking their dose first thing in the morning upon waking or right before bed at night.
Safety, Drug Interactions & Medical Precautions
Dietary supplements that influence blood rheology require thoughtful medical coordination. While nattokinase has an outstanding safety record across dozens of clinical studies, responsible health management requires observing the following guidelines:
Important Medical Guidance:
Prescription Anticoagulants & Antiplatelets: Do not combine nattokinase with prescription blood thinners (such as warfarin/Coumadin®, heparin, apixaban/Eliquis®, rivaroxaban/Xarelto®, or clopidogrel/Plavix®) or high-dose aspirin without direct physician supervision, as additive fibrinolytic actions may increase bleeding risk.
Blood Pressure Medications: Because nattokinase naturally supports blood pressure relaxation, monitor your readings closely if taking ACE inhibitors, beta-blockers, or diuretics to avoid hypotensive episodes.
Surgery & Dental Procedures: Discontinue use at least 14 days before any scheduled surgery or invasive dental procedure to prevent excessive bleeding.
Pregnancy & Nursing: If you are pregnant, may become pregnant, or are breastfeeding, consult your healthcare practitioner prior to use.
Regulatory Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This product is a dietary supplement and is not intended to diagnose, treat, cure, or prevent any disease. Always speak with your qualified physician before altering any medical regimen.
Complete Ingredient Listing & Supplement Facts
Supplement Facts
Serving Size: 1 Capsule Servings Per Container: 60
Amount Per Serving
% Daily Value
Nattokinase (NSK-SD®) delivering 4,000 Fibrinolytic Units (FU)
200 mg *
* Daily Value not established.
Other Ingredients: Microcrystalline cellulose, gelatin (capsule), silica, and magnesium stearate.
Allergen Information: Contains soy.
Free of Common Allergens: Contains NO yeast, dairy, egg, gluten, wheat, sugar, preservatives, artificial colors, artificial flavors, or fragrances.
Frequently Asked Questions (FAQ)
What is Nattokinase NSK-SD® 200 mg and how is it made?
Nattokinase is a purified systemic enzyme extracted from natto, a traditional Japanese food made from fermented non-GMO soybeans. Source Naturals uses NSK-SD®, a patented, clinically studied form fermented by Japan Bio Science Laboratories using a proprietary strain of Bacillus subtilis var. natto. The 200 mg dose provides double the potency of typical nattokinase supplements.
What does 4,000 FU mean on the label?
FU stands for "Fibrinolytic Units." Unlike regular vitamins measured solely by milligram weight, enzymes are measured by their biological activity—specifically how effectively they break down fibrin protein webs in laboratory assays. An activity level of 4,000 FU per capsule indicates high enzymatic strength, delivering twice the standard 2,000 FU daily serving.
Why is Vitamin K2 removed from NSK-SD®?
Whole fermented natto naturally contains very high levels of Vitamin K2. Because Vitamin K helps the liver synthesize blood-clotting proteins, it can counteract the circulation-clearing activity of nattokinase. NSK-SD® undergoes a patented extraction process that reduces Vitamin K2 to less than 0.1 ppm, ensuring you receive pure fibrinolytic benefits without interfering with coagulation balance.
Why must I take nattokinase on an empty stomach?
If taken with food, nattokinase gets used up by your stomach acid to digest the proteins in your meal. To work systemically throughout your cardiovascular system, it must be absorbed into your bloodstream intact. Taking it on an empty stomach with a full glass of water (at least 30 to 45 minutes before eating or 2 hours afterward) allows it to pass directly into your circulation.
Can I take this supplement if I am on prescription blood thinners?
No, not without express approval and ongoing monitoring from your prescribing doctor. Because nattokinase promotes fibrin breakdown and reduces blood viscosity, combining it with medications such as warfarin, Eliquis, Xarelto, or Plavix may compound their blood-thinning effect and elevate your risk of bleeding or bruising.
How long does it take for Nattokinase 200 mg to show results?
Clinical pharmacology studies demonstrate that nattokinase begins breaking down cross-linked fibrin and enhancing circulatory markers within 2 to 4 hours of a single oral dose, remaining active in the blood for over 8 hours. For systemic cardiovascular goals like healthy blood pressure and vascular elasticity, clinical trials report measurable improvements after 8 to 12 weeks of consistent daily supplementation.
