Nattokinase Demonstrates Blood Pressure Reduction in Both Animal and Human Studies
The most robustly demonstrated health benefit of nattokinase across both animal and human studies is blood pressure reduction, with consistent evidence showing significant decreases in both systolic and diastolic blood pressure. 1, 2
Primary Cardiovascular Benefits
Blood Pressure Reduction (Strongest Evidence)
The most compelling evidence comes from randomized controlled trials showing:
- Systolic blood pressure reduction of 3.45-5.55 mmHg in patients with pre-hypertension or stage 1 hypertension 1, 2
- Diastolic blood pressure reduction of 2.32-2.84 mmHg compared to placebo 1, 2
- These effects were achieved with 8-week supplementation at doses of 2,000 FU/capsule 1
The mechanism appears to involve reduction in renin activity (net change of -1.17 ng/mL/h), suggesting nattokinase modulates the renin-angiotensin system 1. A 2023 meta-analysis of 546 participants confirmed these antihypertensive effects with high methodological quality 2.
Fibrinolytic and Antithrombotic Activity
Both animal and human studies demonstrate:
- Direct fibrinolytic properties through its serine protease activity 3, 4
- In animal models (rats), nattokinase restored cerebral blood flow in thrombolytic focal cerebral ischemia, with effects comparable to streptokinase at 300 mg/kg doses 5
- Neuroprotection in ischemic stroke models through reduction of inflammatory cytokines, oxidative stress (ROS), and coagulation factors 6
Secondary Metabolic Effects
Lipid Profile (Dose-Dependent and Mixed Results)
The evidence on lipid-lowering is more nuanced and dose-dependent:
- Low-dose nattokinase (specific threshold not clearly defined) showed paradoxical increases in total cholesterol, LDL, and decreases in HDL 2
- Higher-dose supplementation showed improved total cholesterol but no significant effects on HDL or LDL 2
- Recent 2025 research suggests nattokinase reduces blood lipids by activating hormone-sensitive lipase, inhibiting HMG-CoA reductase, and enhancing lipoprotein lipase activity 7
Clinical Caveat: The lipid-lowering effects are inconsistent and appear less reliable than blood pressure benefits. Do not rely on nattokinase as primary lipid management.
Emerging Metabolic Benefits
Very recent 2026 animal studies show:
- Obesity management: 10,000 U/kg body weight reduced body weight gain, adiposity, and dyslipidemia in high-fat diet-fed mice 8
- Gut microbiota restoration: Reversed dysregulated Bacteroidetes/Firmicutes ratio 8
These metabolic effects require human validation before clinical application.
Anti-Inflammatory and Antioxidant Properties
Both in vitro and animal models demonstrate:
- Reduction of pro-inflammatory cytokines in cerebral ischemia models 5, 6
- Attenuation of oxidative stress (ROS reduction) in ischemic injury 6
- Modulation of multiple cell death pathways: autophagy, apoptosis, PARP-dependent death, and endoplasmic reticulum stress 6
These effects are dependent on enzymatic activity - heat-inactivated nattokinase loses neuroprotective properties 6.
Safety Profile
Comprehensive toxicology studies show:
- Non-mutagenic and non-clastogenic in vitro 9
- 90-day oral NOAEL of 1,000 mg/kg/day in rats (highest dose tested) 9
- Well-tolerated in humans at 10 mg/kg/day for 4 weeks 9
- No notable adverse events reported across clinical trials 2
Critical Clinical Considerations
Important Caveats:
- The lipid effects are inconsistent and may be counterproductive at lower doses
- All neuroprotective and metabolic benefits beyond blood pressure require further human validation
- The enzyme activity is essential - ensure products maintain proper storage and handling
- Patients on anticoagulants should exercise caution given the fibrinolytic properties
Bottom Line: While nattokinase shows promise across multiple domains, blood pressure reduction remains the only consistently demonstrated benefit in adequately powered human trials. The fibrinolytic activity is well-established mechanistically and in animal models, but large-scale human outcome trials for thrombotic events are lacking.