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Natto / Vitamin K2 (for Arteries) Side Effects & Safety

Evidence:Moderate
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This content is for informational purposes only and does not constitute medical advice. Statements about dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary — consult your healthcare provider before starting any supplement. Full disclaimer

Safety Profile

Overall safety rating: Safe with Caution

Potential Side Effects

  • Generally very well-tolerated at recommended doses
  • Mild GI discomfort (rare)
  • Nattokinase: increased bleeding risk in susceptible individuals
  • Allergic reaction in those with soy allergy (nattokinase derived from soy)

Drug & Supplement Interactions

  • Warfarin/vitamin K antagonists — K2 directly opposes warfarin mechanism; do NOT combine without medical supervision
  • Anticoagulants and antiplatelets — nattokinase may increase bleeding risk
  • Vitamin D — synergistic for calcium metabolism; often taken together beneficially

Maximum Dose

Do not exceed: 360mcg MK-7/day; 4000 FU nattokinase/day

Full Natto / Vitamin K2 (for Arteries) Guide

References

  1. RCTKnapen MH, Braam LA, Drummen NE, Bekers O, Hoeks AP, Vermeer C (2015). Menaquinone-7 supplementation improves arterial stiffness in healthy postmenopausal women. A double-blind randomised clinical trial. Thrombosis and Haemostasis. DOI PubMed
  2. ObservationalGeleijnse JM, Vermeer C, Grobbee DE, Schurgers LJ, Knapen MH, van der Meer IM, Hofman A, Witteman JC (2004). Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study. Journal of Nutrition. DOI PubMed
  3. RCTKurosawa Y, Nirengi S, Homma T, Esaki K, Ohta M, Clark JF, Hamaoka T (2015). A single-dose of oral nattokinase potentiates thrombolysis and anti-coagulation profiles. Scientific Reports. DOI PubMed