Does Nattokinase Cause Brain Hemorrhage?

One study of a person taking aspirin who then added natto (400 mg/day for 7 days) to his meds and had an intracerebral hemorrhage (ICH) (brain hemorrhage) concluded that nattokinase caused the problem.¹ The logical fallacy this article makes is called post hoc ergo propter hoc, the logical fallacy of "after this therefore because of this." It could very well have been the aspirin that caused the hemorrhage, not the nattokinase. Indeed, this is a more likely conclusion. Especially since natto is a Japanese food and causes no side effects, such as brain hemorrhage. Instead, natto prevents such events and prevents strokes and heart attacks.² Another, more credible, study concluded that aspirin causes brain hemorrhage.³

Warfarin (also known as Coumadin) is an antithrombotic, specifically an anticoagulant. There are three types of antithrombotics: antiplatelet drugs (which reduce platelet aggregation), anticoagulants (which reduce the ability of platelets to clot), and thrombolytic drugs (such as natto, which dissolve clots). Warfarin, commonly given to patients who have had a stroke, also can cause cerebellar hemorrhage (CH), a type of brain hemorrhage.⁴ Warfarin is no more effective than aspirin.⁵

References

1. "Cerebellar hemorrhage provoked by combined use of nattokinase and aspirin in a patient with cerebral microbleeds." Intern Med. 2008;47(5) : 467-9. Epub 2008 Mar 3. Chang YY, Liu JS, Lai SL, Wu HS, Lan MY. http://www.ncbi.nlm.nih.gov/pubmed/18310985
2. "Natto and Its Active Ingredient Nattokinase: A Potent and Safe Thrombolytic Agent." Martin Milner, Kouhei Makise. Alternative and Complementary Therapies. June 2002, 8(3): 157-164. doi:10.1089/107628002760091001.
3. Aspirin-associated intracerebral hemorrhage in a patient with CADASIL." Clin Neurol Neurosurg. 2008 Apr; 110(4) : 384-6. Epub 2008 Jan 22. "Oh JH, Lee JS, Kang SY, Kang JH, Choi JC. http://www.ncbi.nlm.nih.gov/pubmed/18207319?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_SingleItemSupl.Pubmed_Discovery_RA&linkpos=2&log$=relatedarticles&logdbfrom=pubmed
4. "Antithrombotic therapy and predilection for cerebellar hemorrhage." Cerebrovasc Dis. 2007;23(2-3):109-16. Epub 2006 Nov 15. Toyoda K, Okada Y, Ibayashi S, Inoue T, Yasumori K, Fukui D, Uwatoko T, Makihara N, Minematsu K. http://www.ncbi.nlm.nih.gov/pubmed/17124390?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_SingleItemSupl.Pubmed_Discovery_RA&linkpos=1&log$=relatedarticles&logdbfrom=pubmed
5. "Study Shows That Aspirin and Warfarin Are Equally Effective for Stroke Prevention." November 14, 2001. http://www.ninds.nih.gov/news_and_events/news_articles/pressrelease_stroke_prevention_111401.htm