Vitamin K2: MK-7 vs MK-4 — A Science-Based Overview
Vitamin K2 is often overlooked, yet it performs critical functions in the body: directing calcium into bones and keeping it away from arterial walls. The supplement market offers two main forms — MK-7 (menaquinone-7) and MK-4 (menaquinone-4). The difference is more than just a name — they behave remarkably differently in the body.
Key Differences Between MK-7 and MK-4
| Property | MK-7 | MK-4 |
|---|---|---|
| Source | Natto (fermented soybeans) | Animal (liver, chicken fat) |
| Half-life | 72 hours | 1–2 hours |
| Bioavailability | High | Lower (dose-dependent) |
| Effective dose | 90–200 mcg/day | 1000–45,000 mcg/day |
| Fat solubility | High | High |
Why Is MK-7 Preferred at Physiological Doses?
MK-7's long half-life means a single daily dose maintains stable blood levels throughout the day. Research shows that as little as 90 mcg of MK-7 per day effectively activates vitamin K-dependent proteins — osteocalcin and MGP (Knapen et al., 2013). MK-4 is cleared from the blood rapidly and requires 100–500 times larger doses to achieve comparable effects.
Primary Functions of Vitamin K2
Vitamin K2 activates two important proteins:
- Osteocalcin (in bones): binds calcium into bone tissue, increasing bone mineral density.
- MGP — Matrix Gla Protein (in blood vessels): inhibits calcium deposits in arterial walls, protecting cardiovascular health.
A clinical trial demonstrated that MK-7 supplementation (180 mcg per day for 3 years) improved lumbar spine bone density and reduced arterial stiffness in women (Knapen et al., 2015).
Food Sources of Vitamin K2
Best dietary sources:
- Natto (fermented soybeans, Japan): 939 mcg / 100g — exceptionally high
- Hard cheeses: 75 mcg / 100g
- Soft cheeses: 56 mcg / 100g
- Chicken liver: 35 mcg / 100g
- Butter: 15 mcg / 100g
Natto is hard to find in Estonia, making supplements a practical choice for most people.
Which Supplements Contain MK-7?
At maxfit.ee you'll find a wide range of K2 supplements. OstroVit Vitamin K2 200 Natto MK-7 90tabs delivers a high dose of natto-derived MK-7. MK-7 Vitamin K-2, 100 mcg, 60 Veg Capsules by NOW is a classic option for those seeking a standard daily dose. For a combined approach, OstroVit Pharma D3 4000 IU + K2 MK-7 90 Tabs and DY Vitamin D3 + K2 Capsules provide both vitamins in one capsule.
Are There Side Effects With Vitamin K2?
Vitamin K2 is generally safe even at higher doses. Unlike vitamin K1, K2 does not significantly affect blood clotting, but if you take anticoagulants (e.g., warfarin), consult your doctor first, as K vitamins can interact with these medications.
FAQ
Is MK-4 completely useless?
No. MK-4 is important in certain tissues (brain, arteries) where MK-7 may not accumulate as effectively. Some studies have used an MK-4 plus MK-7 combination. However, at typical supplement doses without medical supervision, MK-7 has stronger evidence behind it.
How much vitamin K2 should I take daily?
EFSA recommends 70–100 mcg of vitamin K daily (general), but many experts consider 100–200 mcg of MK-7 per day optimal for bone and vascular health. Higher doses may be used short-term when correcting a deficit.
Should D3 and K2 be taken together?
Yes — the combination is synergistic: D3 increases calcium absorption from the gut, while K2 ensures that calcium is deposited in bones rather than arteries. Taking them together theoretically reduces the risk of soft-tissue calcification (Vermeer et al., 2004).
References
- Knapen, M. H., Drummen, N. E., Smit, E., et al. (2013). Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporosis International, 24(9), 2499–2507.
- Knapen, M. H., Braam, L. A., Drummen, N. E., et al. (2015). Menaquinone-7 supplementation improves arterial stiffness in healthy postmenopausal women. Thrombosis and Haemostasis, 113(5), 1135–1144.
- Vermeer, C., Shearer, M. J., Zittermann, A., et al. (2004). Beyond deficiency: potential benefits of increased intakes of vitamin K for bone and vascular health. European Journal of Nutrition, 43(6), 325–335.
- Schurgers, L. J., & Vermeer, C. (2000). Determination of phylloquinone and menaquinones in food. Haemostasis, 30(6), 298–307.
- Geleijnse, J. M., Vermeer, C., Grobbee, D. E., et al. (2004). Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease. Journal of Nutrition, 134(11), 3100–3105.
