Vitamin K2: The Overlooked Molecule Behind Longevity and Cardiovascular Health
What Is Vitamin K2?
Vitamin K2, or menaquinone, is a fat-soluble vitamin belonging to the vitamin K family, alongside vitamin K1 (phylloquinone), found mainly in leafy green vegetables. Unlike K1, which is primarily involved in blood clotting, vitamin K2 plays a central role in calcium metabolism, directing it toward bones and teeth rather than arteries and soft tissues.
Several forms of vitamin K2 exist, labeled MK-4 to MK-13 depending on the length of their side chain. The two most studied are:
- MK-4: found in animal products (egg yolk, liver, meat), with a short half-life in the body.
- MK-7: derived from bacterial fermentation (notably Japanese natto), with a much longer half-life, making it the preferred form in dietary supplements (Schurgers et al., 2007).
A Bit of History
Vitamin K was discovered in 1929 by Danish biochemist Henrik Dam, who was studying blood clotting in chickens. Its name comes from the German word Koagulation. Dam was awarded the Nobel Prize in Physiology or Medicine in 1943 for this discovery, shared with Edward Doisy.
For decades, research focused mainly on vitamin K1 and its role in coagulation. It wasn't until the 1990s-2000s, largely thanks to the work of Cees Vermeer's team at Maastricht University, that the specific role of K2 in bone and cardiovascular health was uncovered, opening a new field of research into its potential against vascular aging.
The Mechanism: Why Researchers Are So Interested
Vitamin K2 acts as a cofactor for enzymes that activate certain vitamin K-dependent proteins, notably:
- Osteocalcin: a protein produced by osteoblasts that binds calcium to the bone matrix.
- Matrix Gla Protein (MGP): a powerful inhibitor of soft tissue calcification, especially in arterial walls.
Without sufficient activation by vitamin K2, these proteins remain inactive: circulating calcium risks depositing not in the bones but in the arteries, contributing to arterial stiffening â a phenomenon closely associated with cardiovascular aging (Cranenburg et al., 2007).
Potential Benefits Related to Aging
Cardiovascular Health
The Dutch Rotterdam Study, involving over 4,800 participants, showed that high vitamin K2 intake was associated with a significant reduction in aortic calcification and a lower risk of cardiovascular mortality (Geleijnse et al., 2004).
Bone Health
Several Japanese clinical trials studied high-dose MK-4 for osteoporosis prevention, showing a reduced risk of vertebral fractures in postmenopausal women (Iwamoto, 2014). Vitamin K2 is often paired with vitamin D3, with which it works synergistically: D3 increases calcium absorption, while K2 ensures it's properly directed.
Arterial Flexibility and Skin Elasticity
The BKCT (Beaulieu Knapen Calcification Trial) demonstrated that three years of MK-7 supplementation improved arterial flexibility in healthy postmenopausal women (Knapen et al., 2015).
Advantages and Limitations
Advantages:
- Helps direct calcium toward bones rather than arteries.
- Interesting synergy with vitamin D3.
- Well-tolerated forms, few reported side effects.
- The MK-7 form offers better bioavailability and prolonged action.
Limitations and Precautions:
- Large-scale, long-term studies remain limited.
- Major interaction with anticoagulants (warfarin-type): vitamin K2 may reduce their effectiveness â medical advice is essential before supplementing in this case.
- Dietary intake (natto, aged cheeses like gouda or brie, egg yolk, goose liver) is often insufficient in Western diets, making supervised supplementation worth considering.
Where to Find Vitamin K2?
- Natto (Japanese fermented soybeans): the most concentrated source of MK-7.
- Aged cheeses: gouda, edam, brie.
- Egg yolk and organ meats: rich in MK-4.
- Dietary supplements: usually in MK-7 form, often combined with vitamin D3 and sometimes calcium or magnesium.
Ongoing Research
Current research is exploring vitamin K2's role in preventing cognitive decline, kidney health (particularly in dialysis patients), and its interaction with the gut microbiome, which participates in the endogenous synthesis of certain menaquinone forms. Larger clinical trials are underway to confirm the benefits observed in cohort studies (Halder et al., 2019).