Micronutrients & recovery
Daily supplementation with natto-derived menaquinone-7 (MK-7) at doses of 50 µg or higher significantly interferes with oral anticoagulant therapy (specifically acenocoumarol) by reducing the INR, whereas synthetic vitamin K1 requires much higher doses (≥315 µg/d) to produce a similar clinical effect.
If you take oral anticoagulants like acenocoumarol or warfarin, avoid MK-7 (natto-derived) supplements above 50 µg/day as they can dangerously lower your INR. Synthetic Vitamin K1 is less likely to interfere at standard doses (<100 µg), but consult your hematologist before starting any Vitamin K supplement.
MK-7 induced more complete carboxylation of osteocalcin, and hematologists should be aware that preparations supplying 50 µg/d or more of MK-7 may interfere with oral anticoagulant treatment in a clinically relevant way.
Why this rating
Controlled clinical study in healthy volunteers on stable anticoagulation, but small sample size (n=12) and extrapolation to broader populations.
Source
Vitamin K–containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7
Leon J. Schurgers et al. · Blood · 2006
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