Vitamin K2 and the heart: what the Rotterdam Study found

What does the research say?

In a large Dutch population study, people who ate the most vitamin K2 (menaquinone) had a lower risk of dying from coronary heart disease than those who ate the least. Vitamin K1 — from leafy greens — didn’t show the same association. This kind of study shows an association, not cause and effect.

The science

Vitamin K is needed to activate proteins involved in blood clotting and in regulating where calcium is deposited in the body, including matrix Gla protein in the artery wall. Vitamin K2 is found mainly in fermented foods (notably natto) and some animal foods such as hard cheese and egg yolk.

In the Rotterdam Study, dietary intake was estimated from a food frequency questionnaire. After adjusting for other risk factors, the highest third of menaquinone intake was associated with a lower relative risk of coronary heart disease mortality (RR ≈ 0.43) and less severe aortic calcification, compared with the lowest third.

Separately, a pharmacokinetic study comparing vitamin K1 with natto-derived MK-7 found MK-7 stayed in the blood far longer, which is one reason natto is of research interest.

Key findings

Higher dietary K2 was associated with lower coronary heart disease mortality.
Higher K2 intake was associated with less severe aortic calcification.
No comparable association was seen for vitamin K1.
MK-7 from natto has a much longer half-life in blood than K1.

Limitations

Observational: people eating more K2 may differ in other ways that affect heart health.
Diet was self-reported at a single point in time.
In this Dutch population, K2 came largely from cheese — so it’s hard to separate K2 from other dietary factors.
Anyone taking warfarin or other vitamin K antagonists should speak to their doctor before changing vitamin K intake.

References

Geleijnse JM, Vermeer C, Grobbee DE, et al. Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study. J Nutr. 2004;134(11):3100–3105. doi.org/10.1093/jn/134.11.3100
Schurgers LJ, Teunissen KJF, Hamulyák K, et al. Vitamin K–containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7. Blood. 2007;109(8):3279–3283. doi.org/10.1182/blood-2006-08-040709