Vitamin K-containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7

Schurgers LJ, Teunissen KJ, Hamulyák K, et al. · Blood

The pharmacokinetic case for taking K2 rather than K1: both forms were absorbed well and peaked in serum at 4 hours, but MK-7 has a far longer half-life, giving much more stable serum levels and 7- to 8-fold higher accumulation during prolonged intake, and it carboxylated osteocalcin more completely. The authors warn that 50 ug/day or more of MK-7 can interfere with oral anticoagulant treatment.

Population

Healthy volunteers given single and prolonged oral doses

Intervention

Synthetic vitamin K1 (phylloquinone) versus natto-derived menaquinone-7

Comparator

K1 against MK-7, head to head

Limitations

Small mechanistic trial in healthy volunteers with blood markers as endpoints; appraised from the paper's published summary; nothing measured in bone, artery or joint outcomes.