Researchers examined data from more than 50,000 people taking part in the Danish Diet, Cancer, and Health study over a 23-year period.
They investigated whether people who ate more foods containing vitamin K had a lower risk of cardiovascular disease related to atherosclerosis (plaque build-up in the arteries).
There are two types of vitamin K found in foods we eat: vitamin K1 comes primarily from green leafy vegetables and vegetable oils while vitamin K2 is found in meat, eggs and fermented foods such as cheese.
For vitamin K2, the risk of being hospitalized was 14 percent lower.
This lower risk was seen for all types of heart disease related to atherosclerosis, particularly for peripheral artery disease at 34 percent.
ECU researcher and senior author on the study Dr. Nicola Bondonno said the findings suggest that consuming more vitamin K may be important for protection against atherosclerosis and subsequent cardiovascular disease.
“Current dietary guidelines for the consumption of vitamin K are generally only based on the amount of vitamin K1 a person should consume to ensure that their blood can coagulate,” she said.
“However, there is growing evidence that intakes of vitamin K above the current guidelines can afford further protection against the development of other diseases, such as atherosclerosis.
“Although more research is needed to fully understand the process, we believe that vitamin K works by protecting against the calcium build-up in the major arteries of the body leading to vascular calcification.”
University of Western Australia researcher Dr. Jamie Bellinge, the first author on the study, said the role of vitamin K in cardiovascular health and particularly in vascular calcification is an area of research offering promising hope for the future.
“Cardiovascular disease remains a leading cause of death in Australia and there’s still a limited understanding of the importance of different vitamins found in food and their effect on heart attacks, strokes and peripheral artery disease,” Dr. Bellinge said.
“These findings shed light on the potentially important effect that vitamin K has on the killer disease and reinforces the importance of a healthy diet in preventing it.”
Next steps in the research
Dr. Bondonno said that while databases on the vitamin K1 content of foods are very comprehensive, there is currently much less data on the vitamin K2 content of foods. Furthermore, there are 10 forms of vitamin K2 found in our diet and each of these may be absorbed and act differently within our bodies.
“The next phase of the research will involve developing and improving databases on the vitamin K2 content of foods.
“More research into the different dietary sources and effects of different types of vitamin K2 is a priority,” Dr. Bondonno said.
Additionally, there is a need for an Australian database on the vitamin K content of Australian foods (e.g. vegemite and kangaroo).
To address this need, Dr. Marc Sim, a collaborator on the study, has just finished developing an Australian database on the vitamin K content of foods which will be published soon.
The paper “Vitamin K intake and atherosclerotic cardiovascular disease in the Danish Diet Cancer and Health Study’ was published in the Journal of the American Heart Association.
Vitamin K is a fat-soluble vitamin including vitamin K1 (K1; phylloquinone) from green leafy vegetables and vegetable oils as the main dietary sources, and vitamin K2 (K2; menaquinones) from dairy products, meat and egg yolk as the main dietary sources in Europe.1–3 K2 has a longer half-life in the circulation than K1.4
Both are absorbed from the small ileum and jejunum. K1 and K2 are incorporated into chylomicrons and delivered to the liver. K2 is also transported via low-density lipoprotein and high-density lipoprotein (HDL) particles to extrahepatic tissue.4 5
Vitamin K functions as a cofactor for the enzyme gamma-glutamyl carboxylase which converts protein-bound glutamate residues into gammacarboxyglutamate (Gla).6 7 Gla-containing proteins are involved in, for example, the coagulation of blood,8 inhibition of arterial calcification (Matrix Gla Protein) and vascular smooth muscle cell apoptosis and movement that is considered protective against vascular injury (Gas-6).9
Matrix Gla Protein is involved in both medial and intimal calcification, and low vitamin K status has been associated with both types of calcification.10–14 In addition, a study that examined the effect of warfarin (a vitamin K antagonist) on medial and intimal plaque calcification in apoE−/− mice concluded that warfarin accelerates both medial and intimal calcification of atherosclerotic plaque.15
Patients with both medial and intimal calcification have a higher cardiovascular risk when compared with similar patients without calcification.16 17 Therefore, an inverse association between vitamin K intake and coronary heart disease (CHD) could be expected.
Results from observational studies on the association between intake of vitamin K and CHD are inconsistent.18–24 Among the identified studies, three found reduced risk of CHD in multivariable adjusted analyses at higher dietary K219 20 or K1.24
Nordic Nutrition Recommendations include a provisional recommended intake of vitamin K of 1 µg/kg body weight per day,3 while adequate intake is 90 µg/day for women and 120 µg/day for men.25 However, these recommendations may not be sufficient to attain complete carboxylation of extrahepatic vitamin K-dependent proteins.26 27
Given the limited number of epidemiological studies,18–24 and the fact that dietary vitamin K sources and content differ between countries,28–31 further research is warranted. The purpose of the current study was to evaluate the association between intake of both K1 and K2 and subsequent CHD events among community-living middle-age adults in Norway.
reference link : https://bmjopen.bmj.com/content/10/5/e035953
More information: Jamie W. Bellinge et al, Vitamin K Intake and Atherosclerotic Cardiovascular Disease in the Danish Diet Cancer and Health Study, Journal of the American Heart Association (2021). DOI: 10.1161/JAHA.120.020551
