Nattokinase
Also known as: NK, subtilisin NAT, Bacillus subtilis natto enzyme
Effective Dosage
2,000–8,000 FU (fibrinolytic units) daily based on study doses
What the Science Says
Nattokinase is a protein-digesting enzyme extracted from natto, a traditional Japanese fermented soybean food. It has fibrinolytic (clot-dissolving) activity in lab settings and is marketed for cardiovascular support. Clinical trials show it may modestly reduce LDL cholesterol and total cholesterol when combined with other compounds like red yeast rice, but a large 3-year randomized trial found no meaningful effect on artery wall thickness, blood pressure, or clotting markers in healthy adults.
What It Doesn't Do
Won't prevent heart attacks or strokes — the best available trial showed zero effect on artery health over 3 years. Doesn't reliably lower blood pressure in clinical trials. Won't improve overall cognitive function — a 6-month RCT found no improvement in global cognition scores. Not a replacement for statins or anticoagulants. The cholesterol benefits seen in studies used a combination product with red yeast rice, so nattokinase alone may not deserve the credit.
Evidence-Based Benefits
Nattokinase has demonstrated modest lipid-lowering effects (reducing TC, LDL-C, non-HDL-C) when combined with Monascus in a 4-month RCT (PMID: 37836525), and showed safety and symptom improvement in vascular disease patients including DVT and venous insufficiency (PMID: 34199189). In a stroke rehabilitation context, it showed supportive effects on functional recovery scores as an adjunct to standard care (PMID: 31934821), and animal models suggest neuroprotective mechanisms via Nrf2-associated antioxidative pathways (PMID: 41760340).
Weak EvidenceEffective at: 2000-8000 FU/day based on clinical trials; no consensus established
Source: auto-research
Absorption & Bioavailability
Unknown — oral absorption of intact enzyme is debated. Studies use fibrinolytic units (FU) rather than mg, suggesting activity is measured functionally. No pharmacokinetic data provided in the reviewed papers.
Red Flags to Watch For
- Serious bleeding risk: nattokinase has anticoagulant and fibrinolytic activity — do NOT combine with blood thinners (warfarin, aspirin, heparin, NOACs) without physician supervision
- One case report links nattokinase supplementation to aggravated histamine intolerance in people with diamine oxidase deficiency
- Most positive cholesterol data comes from a combination product (nattokinase + red yeast rice), making it impossible to isolate nattokinase's contribution
- The largest long-term cardiovascular RCT (3 years, 265 participants) showed a null result — no benefit on any cardiovascular marker
- Long COVID use is speculative — listed only as a candidate for future trials with no direct RCT evidence
Research Sources
- PubMed
- NIH DSLD
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-04-06