Critical Reasons to Avoid Nattokinase
Individuals Taking Blood-Thinning Medications
One of the most important groups who should avoid taking nattokinase are those on anticoagulant or antiplatelet drugs. Nattokinase functions as a natural blood thinner by breaking down fibrin, the protein responsible for clotting. When combined with prescription medications that also slow blood clotting, this can create a dangerously synergistic effect, dramatically increasing the risk of excessive bleeding, bruising, and even hemorrhage. Medications to be cautious with include:
- Warfarin (Coumadin)
- Heparin
- Clopidogrel (Plavix)
- Aspirin (especially daily doses)
- NSAIDs like ibuprofen and naproxen
- Apixaban (Eliquis) and other novel anticoagulants
People with Bleeding Disorders or Recent Hemorrhage
Individuals with pre-existing bleeding disorders, such as hemophilia, should completely avoid nattokinase. Its potent fibrinolytic activity could exacerbate their condition, leading to uncontrollable bleeding. Additionally, those with a history of intracranial hemorrhage or other bleeding events should not take this supplement. An unfortunate case involved an elderly woman who developed a fatal hemoperitoneum after taking nattokinase for atrial fibrillation. Another report detailed a cerebellar hemorrhage in a patient who combined aspirin and nattokinase.
Patients Planning for or Recovering from Surgery
Due to its powerful blood-thinning properties, nattokinase must be discontinued well in advance of any surgical procedure, including dental surgery. The typical recommendation is to stop at least two weeks beforehand to minimize the risk of excessive bleeding during and after the operation. Blood clotting is a vital part of the healing process, and nattokinase can interfere with this.
Pregnant or Breastfeeding Women and Children
There is a significant lack of reliable research on the safety of nattokinase for pregnant and breastfeeding individuals and for children. Because its effects can thin the blood and potentially cause bleeding complications, pregnant women are advised to avoid it. For children, the safety and proper dosage are not established, so use should be avoided.
Individuals with Very Low Blood Pressure
Nattokinase has been observed to help lower blood pressure in some studies. For those who already have low blood pressure (hypotension) or are taking medications to lower it, adding nattokinase could cause blood pressure to drop dangerously low. Symptoms of excessively low blood pressure, such as dizziness or fainting, could result.
People with Soy Allergies
Since nattokinase is derived from fermented soybeans (natto), individuals with a soy allergy should avoid it. Allergic reactions can range from mild urticaria to severe anaphylaxis.
Nattokinase Risk Comparison Table
| Medical Condition/Group | Primary Risk with Nattokinase | Rationale for Caution | Severity |
|---|---|---|---|
| Taking blood-thinners | Excessive bleeding, hemorrhage | Potentiates effects of anticoagulant/antiplatelet drugs | High |
| Bleeding disorders | Uncontrollable bleeding | Amplifies underlying coagulation issues | High |
| Upcoming surgery | Excessive bleeding during procedure | Interferes with natural clotting process | High |
| Pregnancy/Breastfeeding | Potential bleeding complications | Insufficient safety data in these populations | High |
| Hypotension (low BP) | Dangerously low blood pressure | May have additive blood pressure-lowering effects | Moderate |
| Soy allergy | Allergic reaction, anaphylaxis | Contains soy-based proteins from the fermentation process | Moderate to High |
| Post-stroke/Vascular lesions | Clot dislodgement, embolism | Theoretically could cause existing clots to move | High |
Considerations Before Supplementation
Beyond the primary contraindications, there are other important factors to consider before taking nattokinase.
- Lack of Standardization: Unlike FDA-approved drugs, nattokinase supplements lack standardized dosing regimens, and monitoring parameters are not well-established. This makes it difficult to predict the exact potency and effect of different products.
- Existing Clots: There is a theoretical risk that nattokinase's fibrinolytic properties could cause an existing clot to dislodge and travel to another location, potentially leading to a stroke or embolism. Patients with a history of deep vein thrombosis (DVT) or stroke should be particularly cautious.
- Dosage Uncertainty: Safe and effective dosing has not been determined through rigorous clinical trials. While some studies use a standard dosage of 2,000 Fibrinolytic Units (FU), individual needs and risks can vary significantly.
- Herbal and Drug Interactions: The potential for interactions is not limited to blood thinners. Anyone on regular medication for cardiovascular conditions, such as high blood pressure, should consult a physician. Additionally, combining nattokinase with other supplements, such as ginkgo biloba, may also increase bleeding risk.
- Lack of Long-term Data: Most studies on nattokinase are short-term. There is no substantial evidence on the long-term safety of taking the supplement for more than 12 months.
- Regulation: In many countries, including the US, nattokinase is sold as a dietary supplement with limited FDA regulation, meaning manufacturers are responsible for ensuring safety and labeling accuracy. This emphasizes the importance of professional medical advice.
Conclusion
While nattokinase is recognized for its potential cardiovascular benefits, its potent blood-thinning properties necessitate extreme caution for several groups. Individuals taking anticoagulant medications, those with known bleeding disorders, and patients awaiting or recovering from surgery should strictly avoid its use. Due to a lack of sufficient safety data, pregnant or breastfeeding women and children should also abstain. The potential for adverse interactions and side effects, including serious bleeding events, makes it essential to consult a healthcare provider before considering nattokinase. Relying on professional medical guidance is the safest approach to determine if this supplement is appropriate for your individual health status.
Key Takeaways
- Blood-thinning Medication: Do not take nattokinase if you are on anticoagulants or antiplatelet drugs like warfarin, heparin, or aspirin, as it significantly increases bleeding risk.
- Surgical Procedures: Discontinue nattokinase at least two weeks before any scheduled surgery to prevent excessive bleeding during or after the procedure.
- Bleeding Risk Conditions: Individuals with bleeding disorders, recent stroke, or a history of hemorrhage should avoid nattokinase due to potential complications like hemorrhage or clot dislodgement.
- Vulnerable Populations: Pregnant and breastfeeding women, along with children, should not take nattokinase because of insufficient safety data in these populations.
- Professional Consultation: Always speak with a healthcare provider before starting nattokinase, especially if you have existing health conditions or take other medications.
