On the other hand, no such associations were observed for vitamin K1 (phylloquinone), wrote researchers from The Netherlands in Clinical Nutrition.
No risk reductions from dying of cardiovascular disease (CVD), cancer, or other causes were observed for either K1 or K2 intakes.
Commenting on the study’s findings, Hogne Vik, chief medical officer with NattoPharma, supplier of MenaQ7 Vitamin K2 as MK-7, said: “As with the Rotterdam Study (2004) and Prospect-EPIC Study (2009), a link has been established between intake of long-chain menaquinones and cardiovascular health. Improving one’s K2 status results in less calcification of the arteries and soft tissues, leading to improved long-term health outcomes.
“These benefits are recognized with Vitamin K2, but not K1, which is important because there is a misconception that daily recommended intake (RDI) of the vitamin K1 is sufficient to protect the arteries for developing arterial diseases. This is not the case, since vitamin K1 is only documented and recognized to meet our needs for coagulation. It is, however, vitamin K2, the menaquinones, that are responsible for the cardiovascular benefits, and not vitamin K1.”
K forms
There are two main forms of vitamin K: phylloquinone (vitamin K1), which is found in green leafy vegetables such as lettuce, broccoli and spinach, and makes up about 90% of the vitamin K in a typical Western diet; and menaquinones (vitamins K2), which make up about 10% of Western vitamin K consumption and can be synthesized in the gut by microflora.
Menaquinones (MK-n: with the n determined by the number of prenyl side chains) can also be found in the diet; MK-4 can be found in animal meat, MK-7, MK-8, and MK-9 are found in fermented food products like cheese, and natto is a rich source of MK-7.
The potential health benefits of the vitamin include cardiovascular and bone health, with some data also supporting a role for prostate health and cognitive benefits.
Study details
The researchers followed 33,289 participants aged between 20 and 70 years for almost 17 years, and during that time they documented 2,863 deaths, with 625 from CVD (256 from CHD), 1,346 from cancer, and 892 from other causes.
After crunching the numbers, the researchers elucidated that neither phylloquinone nor menaquinones had any significant impacts on all-cause mortality, or with risk of CVD mortality.
However, the highest intakes of long-chain menaquinones were associated with a 14% reduction in CHD mortality, and this reached borderline statistical significance.
Commenting on the potential mechanism of action, the researchers said that this was perhaps related to a reduction in arterial calcification.
“Consistent with this hypothesis, previous studies found inverse associations of menaquinone intake, especially long chain menaquinones, with CHD incidence and coronary calcification,” they wrote. “Although we did not observe strong associations, our results on CHD mortality are in line with these findings.
“None of [these earlier] studies found an association of phylloquinone with CHD, consistent with our study. This discrepancy between phylloquinone and menaquinones intake could be explained by the differences in their metabolism. Because phylloquinone is cleared rapidly by the liver and menaquinones are redistributed by the liver and transported by LDL, they have a longer half-life time and may be more available to extra hepatic tissues.”
NattoPharma’s Vik said that the study confirms data from a three-year interventional study, which found that vitamin K2 could improve arterial health and flexibility (Thrombosis and Haemostasis, 2015, Vol. 113, pp. 1135-1144).
“We are enthused to see additional studies confirming this mechanism and encourage the nutritional community to embrace Vitamin K2 for its unique and specific benefits,” he said.
Source: Clinical Nutrition
Published online ahead of print, doi: 10.1016/j.clnu.2016.08.017
“Vitamin K intake and all-cause and cause specific mortality”
Authors: S.R. Zwakenberg et al.