What supplements should not be taken with nattokinase?

The riskiest thing about nattokinase is not the enzyme itself — it is what people take alongside it without thinking twice.

Nattokinase has a reasonable safety record on its own. A retrospective study of 1,062 participants taking it daily for 12 months [4] reported no serious safety signals. The problem is additive. Roughly one in three US adults uses herbal supplements [2], often without telling anyone — and several of the most popular ones push blood in the same direction nattokinase does.

Table of Contents

• 1. Why Stacking Matters More Than Any Single Supplement
• 2. Other Fibrinolytic Enzymes: The Highest-Overlap Category
• 3. Antiplatelet Botanicals: Garlic, Ginkgo, Ginger and Curcumin
• 4. Omega-3s and High-Dose Vitamin E
• 5. Vitamin K2: The Interaction That Runs the Other Way
• 6. Surgery, Procedures and Practical Timing
• 7. BioAbsorb Nattokinase Enzyme — Knowing What Is Actually in the Capsule
• Frequently Asked Questions
• Conclusion
• Research References

1. Why Stacking Matters More Than Any Single Supplement

Nattokinase reduces the blood's tendency to clot through more than one route at once. That is what makes it interesting for cardiovascular support — and it is also why the question of what to combine it with is not a minor footnote. When two supplements push the same system in the same direction, the effects do not simply sit side by side. They add.

A 2025 review in the International Journal of Molecular Sciences makes this explicit. It places nattokinase among a group of widely used cardiovascular supplements with overlapping antiplatelet or anticoagulant mechanisms [1], alongside omega-3 fatty acids, berberine and garlic. The review separately flags ginkgo biloba, ginger, ginseng and curcumin as raising bleeding risk when combined with antithrombotic therapy, and groups vitamin C, vitamin E, resveratrol, astaxanthin and coenzyme Q10 as antioxidants that can interfere with hemostasis. The review's central observation is that these products are frequently taken together by people who assume "natural" means the combination is neutral.

The honest caveat belongs here rather than buried at the end. A 2012 review in Nutrition Reviews examining six of these supplements concluded that controlled human studies remain too limited to demonstrate consistent anticoagulant effects [3], alone or in combination. A 2018 review in Advances in Nutrition reached a similar position, noting that much of the evidence for antiplatelet supplements is based on in vitro work rather than clinical outcomes [5]. Mechanism is clearer than outcome data. That argues for caution, not alarm.

One scope note: this article is about combining nattokinase with other supplements. Prescription anticoagulants and antiplatelet drugs — warfarin, DOACs, aspirin, clopidogrel — are a separate and more serious conversation, covered in full in our guide to nattokinase as a natural blood thinner. If you take any of those, that article should come first.

2. Other Fibrinolytic Enzymes: The Highest-Overlap Category

If there is one category to be most careful with, it is other systemic enzymes. Serrapeptase, lumbrokinase and bromelain all act on protein structures in ways that overlap with nattokinase's core activity. Stacking two fibrinolytic enzymes is not diversification — it is dose escalation by another name.

Serrapeptase is the most common pairing, and the two appear together in several commercial "systemic enzyme" blends. Controlled human data on the combination specifically is thin: a randomised controlled trial of an enteric-coated serrapeptase-and-nattokinase product in idiopathic pulmonary fibrosis patients [7] is one of very few. The theoretical rationale for combining them — nattokinase for circulatory fibrinolysis, serrapeptase for localised inflammation — is reasonable, but reasonable is not the same as demonstrated. Our comparison of nattokinase and serrapeptase sets out the case for choosing one rather than running both.

The most sobering data point in this category is not about oral use at all. Memorial Sloan Kettering's clinical database documents a case in which a 47-year-old man lost an arm to vascular necrosis [9] after injecting an oral enzyme product containing both serrapeptase and nattokinase; the original case report describes a transhumeral amputation after attempts to salvage the limb failed [12]. That is an extreme misuse case rather than a stacking risk — but it is a reminder that these are pharmacologically active compounds, not gentle wellness powders.

• Serrapeptase — the most frequent co-supplement; overlapping proteolytic activity, limited combination data
• Lumbrokinase — earthworm-derived fibrinolytic enzyme; often stacked in online protocols with almost no human safety data on the pair
• Bromelain — pineapple-derived protease with mild antiplatelet activity; frequently included in blends without being listed prominently
• Multi-enzyme "systemic" blends — check the full label; a single product may already contain 3 or more of the above

3. Antiplatelet Botanicals: Garlic, Ginkgo, Ginger and Curcumin

This is where the evidence gets more interesting, because it is genuinely uneven — and most articles on this topic flatten that unevenness into a single warning list. A 2022 review in Proceedings (Baylor University Medical Center) graded the evidence supplement by supplement and found that garlic and hawthorn were strongly associated with surgical bleeding even without anticoagulants [2], while cordyceps, echinacea and aloe vera showed only loose associations.

The same review placed ginkgo biloba, turmeric, chondroitin-glucosamine, melatonin, bilberry, chamomile, fenugreek, milk thistle and peppermint in a different bracket: associated with bleeding risk in people already taking anticoagulants, but without evidence of independent risk [2]. Evidence for ginger, St John's wort and cranberry was described as conflicting. Two of those nine — turmeric and melatonin — sit in a very large number of household supplement cupboards.

Concentrated garlic supplements are the clearest concern in this group, and worth separating from food. Garlic used in normal cooking quantities is not the issue; standardised extracts delivering allicin at supplement doses are. Ginkgo's mechanism is distinct from nattokinase's — it inhibits platelet-activating factor rather than fibrin — which means the two affect different points in the same cascade, and the effects compound rather than overlap. The 2012 Nutrition Reviews analysis noted that serious events such as spinal epidural hematoma and spontaneous intracerebral hemorrhage [3] have been anecdotally linked to supplement use, though causation remains unestablished.

4. Omega-3s and High-Dose Vitamin E

Fish oil is probably the single most common supplement taken alongside a cardiovascular enzyme, which makes its evidence profile worth getting right. It is more reassuring than its reputation suggests. The 2022 Baylor review found no association between fish oil and bleeding [2], placing it in the same bracket as ginseng and saw palmetto.

A systematic review of omega-3 supplementation in older adults reached a comparable conclusion. Screening 398 citations down to 10 randomised trials covering 994 adults aged 60 and over [8], it examined serious adverse events including bleeding. This matters because that age band overlaps heavily with the people most likely to be taking nattokinase in the first place. The practical read: standard fish oil doses are a low-priority concern, while high-dose regimens deserve a conversation with a clinician.

Vitamin E is the more relevant one to watch, and for a mechanistic reason. At supplemental doses it interferes with vitamin K-dependent clotting factor activation — the same family of factors warfarin targets. The 2025 International Journal of Molecular Sciences review lists vitamin E among the antioxidant supplements that can interfere with hemostasis [1], alongside vitamin C, resveratrol, astaxanthin and coenzyme Q10. The small amount inside a standard multivitamin is a different proposition from a dedicated high-dose vitamin E capsule.

5. Vitamin K2: The Interaction That Runs the Other Way

Every other supplement on this page pushes in the same direction as nattokinase. Vitamin K2 pushes against it — and that makes it the most misunderstood item on the list.

Vitamin K is required to activate several clotting factors. Nattokinase breaks down fibrin. Taken together, each partly works against the other. Raw natto — the fermented food nattokinase is extracted from — is naturally very high in K2, which is why high K2 concentrations in natto can lower INR in people taking warfarin [10]. Most manufacturers remove K2 during extraction for exactly this reason, and BioAbsorb's formulation is K2-free.

Here is the part that rarely gets mentioned, and it deserves to be said plainly. Because natto's native K2 content may partly offset the enzyme's fibrinolytic effect, Health Canada raised a concern in 2012 that removing K2 could theoretically increase bleeding risk rather than reduce it [10] — and the same monograph notes that current safety data does not settle the question either way. There is a second signal pointing the same way: the 1,062-participant retrospective study reported that co-administering vitamin K2 and aspirin with nattokinase produced a synergistic effect on outcomes [4]. Both positions are defensible: removing K2 eliminates a real warfarin interaction variable, while potentially removing a natural brake. If you take a separate K2 supplement, or a D3+K2 combination, that is worth raising with your provider rather than resolving alone.

6. Surgery, Procedures and Practical Timing

Stacking risk becomes concrete around surgery, and this is the one section worth acting on regardless of what else you take. The Baylor review's recommendation is to discontinue non-essential supplements two weeks before a procedure [2]. That window covers dental extractions, colonoscopies and biopsies, not only major operations.

The scale of the problem is that clinicians often do not know what patients are taking. The Society for Perioperative Assessment and Quality Improvement convened an expert panel precisely because guidance was lacking, and produced consensus recommendations covering 83 individual dietary supplements [6] — a number that gives some sense of how many products routinely turn up in pre-operative assessments. The NIH's National Center for Complementary and Integrative Health advises disclosing supplement use to providers as far ahead of an operation as possible [11].

A few practical habits reduce risk more than any amount of label-reading:

• Audit the full stack, not one product — check your routine against the overlapping supplements named in the 2025 review and count how many you are taking
• Bring the bottles — take actual labels to appointments rather than trying to recall doses
• Add one thing at a time — introducing a new supplement alongside nattokinase makes any change hard to attribute
• Watch for early signals — easy bruising, prolonged bleeding from minor cuts, or bleeding gums warrant stopping and calling your provider

7. BioAbsorb Nattokinase Enzyme — Knowing What Is Actually in the Capsule

Most of the stacking risk described above comes from uncertainty: not knowing what is in a product, at what activity level, or whether a blend already contains a second enzyme. Formulation transparency is the practical countermeasure.

BioAbsorb Nattokinase Enzyme is a single-ingredient product: 100 mg standardised to 2000 FU per capsule, one capsule daily on an empty stomach. It is not a systemic enzyme blend, which means there is no second fibrinolytic enzyme hidden in the formula — a meaningful distinction when the main risk in this category is unintentional double-dosing across two products.

Activity units matter more than milligrams. Fibrinolytic units measure enzymatic activity rather than powder weight, and two products both listing 100 mg can differ substantially in active enzyme. Each BioAbsorb batch is third-party tested to confirm activity at 2000 FU or above, along with heavy metals, gluten and microbial contaminants. Manufacturing is in a GMP-certified facility in Canada.

The capsule uses DRcaps delayed-release technology, which protects the enzyme through the stomach without the phthalates and plasticizers used in many enteric coatings. The formulation is non-GMO and free from gluten, nuts, eggs, dairy, fish, shellfish and all animal products. It is also free of vitamin K2 — a choice discussed honestly in section 5 above, including Health Canada's counterpoint. Full ingredient, potency and pricing details are on the BioAbsorb Nattokinase Enzyme product page.

Frequently Asked Questions

Can I take nattokinase and serrapeptase together?

Many commercial products combine them, but controlled human evidence on the pair is limited — the randomised trial in pulmonary fibrosis patients cited above is among the few [7]. Because both are proteolytic enzymes with fibrinolytic activity, running them together is closer to increasing your dose than to adding a different benefit. If you are considering both, discuss it with a healthcare provider rather than stacking them independently.

Is fish oil safe to take with nattokinase?

The evidence is more reassuring than fish oil's reputation suggests: the 2022 Baylor review found no association between fish oil and bleeding, grouping it with ginseng and saw palmetto [2]. That said, high-dose omega-3 regimens are a different case from standard doses, and a systematic review of 994 adults aged 60 and over [8] looked specifically at adverse events in the age group most likely to be taking both. Standard doses are a low-priority concern; high doses warrant a conversation.

What about turmeric or curcumin?

Turmeric sits in the bracket the 2022 Baylor review described as associated with bleeding risk in people already on anticoagulants [2], without clear evidence of independent risk. The 2025 International Journal of Molecular Sciences review also lists curcumin among supplements with anti-inflammatory vascular activity that may raise bleeding risk alongside antithrombotic therapy [1]. Culinary quantities are a different matter from concentrated extracts.

Should I stop taking nattokinase before surgery?

Yes — and earlier than most people expect. The general recommendation for non-essential supplements is two weeks before a procedure [2], and NCCIH advises telling your care team as far in advance as possible [11]. This applies to dental work and minor procedures as well as major surgery. Bring the actual bottles to your pre-operative appointment.

Does taking vitamin K2 cancel out nattokinase?

They work in opposite directions — vitamin K activates clotting factors while nattokinase breaks down fibrin — so a degree of mutual interference is expected. What is less widely known is that Health Canada raised the reverse concern in 2012 [10]: that removing K2 from nattokinase supplements might theoretically increase bleeding risk by removing a natural offset. If you take a separate K2 or D3+K2 product, raise it with your provider.

How many supplements is too many to combine with nattokinase?

There is no validated threshold, and anyone offering one is overstating the evidence. A practical approach is to check your routine against the overlapping supplements identified in the 2025 review [1] and count how many you are taking. Two or more from that list alongside nattokinase is a reasonable trigger for a clinician conversation, particularly if you are over 60 or have any bleeding history.

Conclusion

The supplements to be most careful with alongside nattokinase are other fibrinolytic enzymes, concentrated garlic, ginkgo, high-dose vitamin E and — for the opposite reason — vitamin K2. Nattokinase's own safety record is reasonable, with 1,062 participants studied over 12 months at 10,800 FU daily [4] without serious safety signals — several times a standard supplemental dose — but that record reflects the enzyme taken on its own. If you want a single-ingredient product with confirmed activity and no hidden second enzyme, BioAbsorb Nattokinase Enzyme delivers 2000 FU per capsule with full third-party testing — and your provider should still see the full list of what you take.

Research References

1. Navigating the Effects of Anti-Atherosclerotic Supplements and Acknowledging Associated Bleeding Risks. International Journal of Molecular Sciences, Vol. 26, Issue 20, Article 10183 (2025). Peer-reviewed review identifying nattokinase, omega-3 fatty acids, berberine and garlic as nutraceuticals whose benefit may be limited by bleeding risk, with ginkgo biloba, ginger, ginseng and curcumin raising bleeding risk alongside antithrombotic therapy, and vitamin C, vitamin E, resveratrol, astaxanthin and coenzyme Q10 able to interfere with hemostasis.
2. Dietary supplements and bleeding. Proceedings (Baylor University Medical Center), Vol. 35, Issue 6, Pages 802–807 (2022). Graded review finding garlic and hawthorn strongly associated with surgical bleeding independent of anticoagulants; fish oil, ginseng and saw palmetto not associated; recommends discontinuing non-essential supplements two weeks pre-procedure.
3. Anticoagulant activity of select dietary supplements. Nutrition Reviews, Vol. 70, Issue 2, Pages 107–117 (2012). Review of garlic, ginkgo biloba, ginger, ginseng, fish oil and vitamin E, concluding that controlled human studies remain too limited to establish consistent anticoagulant effects alone or with drug therapy.
4. Effective management of atherosclerosis progress and hyperlipidemia with nattokinase: A clinical study with 1,062 participants. Frontiers in Cardiovascular Medicine, Vol. 9, Article 964977 (2022). Retrospective study of 1,062 participants over 12 months at 10,800 FU/day. A corrigendum was published 5 December 2022 (Vol. 9, Article 1076420).
5. Dietary Supplements with Antiplatelet Activity: A Solution for Everyone? Advances in Nutrition, Vol. 9, Issue 1, Pages 51–57 (2018). Review concluding that human controlled trials are too limited to establish that antiplatelet supplements are universally safe, alone or combined with antiplatelet therapy.
6. Preoperative Management of Surgical Patients Using Dietary Supplements: Society for Perioperative Assessment and Quality Improvement (SPAQI) Consensus Statement. Mayo Clinic Proceedings, Vol. 96, Issue 5, Pages 1342–1355 (2021). Consensus developed by modified Delphi method, covering perioperative management of 83 individual dietary supplements.
7. A Randomized Controlled Trial of the Safety and Efficacy of Systemic Enzyme Supplementation on Symptoms and Quality of Life in Patients with Idiopathic Pulmonary Fibrosis. Diseases, Vol. 12, Issue 7, Article 155 (2024). Double-blind randomised placebo-controlled trial in 100 IPF patients across six institutions, using an enteric-coated serrapeptase-and-nattokinase regimen — one of few controlled human datasets on the enzyme combination.
8. Fish oil administration in older adults: is there potential for adverse events? A systematic review of the literature. BMC Geriatrics, Vol. 13, Article 41 (2013). Systematic review screening 398 citations to 10 randomised trials covering 994 adults aged 60 and over, assessing serious adverse events including bleeding.
9. Nattokinase — About Herbs Database. Memorial Sloan Kettering Cancer Center. Clinician-reviewed integrative medicine resource documenting reported adverse events, including a vascular necrosis case following injection of an oral serrapeptase-and-nattokinase product.
10. Nattokinase — Professional Monograph. Drugs.com Natural Products database. Clinical monograph citing Health Canada's 2012 concern that removing vitamin K2 from nattokinase supplements could theoretically increase bleeding risk, and noting natto's native K2 effect on INR.
11. Using Dietary Supplements Wisely. National Center for Complementary and Integrative Health, National Institutes of Health. Guidance advising disclosure of all supplement use to healthcare providers as far in advance of surgery as possible.
12. Vascular Necrosis of the Upper Extremity After Self-Treatment for Peyronie's Disease. Sexual Medicine, Vol. 9, Issue 1, Article 100282 (2021). Primary case report of the transhumeral amputation following intravascular self-injection of an oral serrapeptase-and-nattokinase supplement.

About the Author

David Kimbell is a health writer, digital entrepreneur and former aerospace engineer, based in Ottawa, Canada. He loves translating complex science into clear, actionable guidance for consumers seeking evidence-based solutions.

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Important Disclaimers

Medical Disclaimer: This article provides educational information only and is not intended as medical advice. Always consult with a qualified healthcare provider before starting any new supplement, especially if you have existing health conditions, take medications, or are pregnant or nursing.

FDA/Health Canada Statement: These statements have not been evaluated by the Food and Drug Administration or Health Canada. This product is not intended to diagnose, treat, cure, or prevent any disease.