The absorption of MK-4 is rapid, but the action time is short, while the half-life of MK-7 is long. The effective dose of MK-4 needs 45 mg / D, while the effective dose of MK-7 is 45 μg / D, which means that taking MK-7 once a day is enough. In 2012, Sato et al.^[1] completed two bioavailability tests in healthy Japanese women:
　　(1) single dose test: single dose MK-4 (420 μg; 945 nmol) or MK-7 (420 μg) was given together with standardized breakfast in the morning; Results: MK-7 was well absorbed and serum vitamin K2 reached the maximum level 6 hours after administration. The serum containing vitamin K2 could be detected up to 48 hours after administration. However, at any time point after taking MK-4, vitamin K2 in serum of all subjects could not be detected.
　　(2) Continuous administration test: continuous administration of MK-4 (60 μg; 135 nmol) or MK-7 (60 μg; 92 nmol) for 7 days. Results: continuous supplementation of MK-4 for 7 days did not increase serum MK-4 level, but continuous supplementation of MK-7 for 7 days increased serum MK-7 level in all subjects.

References

[1] Sato T, Schurgers LJ, Uenishi K.Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women. Nutr J，2012，11:93.