Available via license: CC BY-NC 4.0
Content may be subject to copyright.
Open access
1
Hariri E, etal. Open Heart 2021;8:e001715. doi:10.1136/openhrt-2021-001715
To cite: Hariri E, Kassis N,
Iskandar J- P, etal. Vitamin
K2—a neglected player in
cardiovascular health: a
narrative review. Open Heart
2021;8:e001715. doi:10.1136/
openhrt-2021-001715
EH and NK contributed equally.
Received 6 May 2021
Accepted 4 October 2021
1Department of Internal
Medicine, Cleveland Clinic
Foundation, Cleveland, Ohio,
USA
2Biochemistry, Maastricht
University CARIM School for
Cardiovascular Diseases,
Maastricht, The Netherlands
3Department of Cardiovascular
Medicine, Cleveland Clinic
Foundation, Cleveland, Ohio,
USA
4Department of Cardiovascular
Medicine, Morristown Medical
Center, Morristown, New Jersey,
USA
Correspondence to
Dr Samir Kapadia; kapadis@
ccf. org
Vitamin K2—a neglected player in
cardiovascular health: a narrative review
Essa Hariri,1 Nicholas Kassis ,1 Jean- Pierre Iskandar,1 Leon J Schurgers,2
Anas Saad,3 Omar Abdelfattah,3,4 Agam Bansal,1 Toshiaki Isogai,3
Serge C Harb ,1 Samir Kapadia3
Cardiac risk factors and prevention
© Author(s) (or their
employer(s)) 2021. Re- use
permitted under CC BY- NC. No
commercial re- use. See rights
and permissions. Published
by BMJ.
ABSTRACT
Vitamin K2 serves an important role in cardiovascular
health through regulation of calcium homeostasis. Its
effects on the cardiovascular system are mediated
through activation of the anti- calcic protein known
as matrix Gla protein. In its inactive form, this protein
is associated with various markers of cardiovascular
disease including increased arterial stiffness, vascular
and valvular calcication, insulin resistance and heart
failure indices which ultimately increase cardiovascular
mortality. Supplementation of vitamin K2 has been strongly
associated with improved cardiovascular outcomes
through its modication of systemic calcication and
arterial stiffness. Although its direct effects on delaying
the progression of vascular and valvular calcication
is currently the subject of multiple randomised clinical
trials, prior reports suggest potential improved survival
among cardiac patients with vitamin K2 supplementation.
Strengthened by its affordability and Food and
Drug Adminstration (FDA)- proven safety, vitamin K2
supplementation is a viable and promising option to
improve cardiovascular outcomes.
INTRODUCTION
Vitamin K is a fat- soluble vitamin that is
comprised of multiple similarly structured
compounds. Naturally, vitamin K occurs as
two vitamers, namely vitamin K1 (phylloqui-
none) and vitamin K2 (menaquinones; MKs).
Vitamin K2 specifically has been highlighted
for its long half- life and extrahepatic activity.
As such, vitamin K2 plays a pivotal role in the
activation of extrahepatic γ-carboxyglutamate
(Gla) proteins such as matrix Gla protein
(MGP), a small 84- amino acid (14 kDa)
protein that is commonly considered the
strongest inhibitor of vascular calcification.1
Primarily synthesised by vascular smooth
muscle cells (VSMCs), MGP undergoes two
forms of post- translational modifications for
complete maturation: γ-glutamate carboxyla-
tion and serine phosphorylation, the former
of which is vitamin- K dependent.2 During
states of vitamin K deficiency, MGP remains
uncarboxylated and its biological function is
impaired.1 There are several forms of MGP
depending on the phosphorylation and
carboxylation status. The circulating inac-
tive unphosphorylated and uncarboxylated
form of MGP (dp- ucMGP) is an established
biomarker for vitamin K deficiency.3 4 The
use of vitamin K antagonists (VKAs) such
as warfarin can induce a deficiency in MGP,
which may contribute to the formation
and evolution of vascular calcification, an
independent predictor of cardiovascular
morbidity and mortality.5
In light of expanding preclinical and clin-
ical data on the cardiovascular benefits of
vitamin K2, with multiple ongoing clinical
trials investigating its role in various outcomes,
there is a pressing need to organise our
understanding of the pathophysiology, safety,
and efficacy of vitamin K2 intake as it relates
to markers and outcomes of cardiovascular
health. The aim of this comprehensive narra-
tive review, divided into two major sections,
is to summarise the literature for scientists
Key points
►There is an alarmingly high prevalence of vitamin
K deciency and suboptimal recommended intake
among the general population in the USA.
►A growing body of evidence supports the potential
role of vitamin K2 in cardiovascular health.
►Vitamin K2 helps regulate the homeostasis of soft
tissue calcication through activation of an anti-
calcic protein known as matrix Gla protein (MGP).
►Studies demonstrate a strong association between
vitamin K deciency, as assessed by plasma inac-
tive MGP, and arterial stiffness, vascular and val-
vular calcication, heart failure and cardiovascular
mortality.
►Increased vitamin K2 intake may reduce arterial
stiffness, slow progression of vascular and valvular
calcication, lower the incidence of diabetes and
coronary artery disease, and decrease cardiovascu-
lar mortality.
►Further efforts are necessary to establish vitamin
K2 as a safe, cost- effective, and efcacious supple-
ment for preventing and improving cardiovascular
outcomes.
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and clinicians on: (1) the role of MGP in cardiovascular
health, and (2) the cardiovascular benefits of vitamin K2
dietary intake and supplementation. We will first discuss
the pathophysiological interplay between vitamin K2 and
MGP. By providing an organised framework of the avail-
able evidence, we will then elucidate the association of
vitamin K deficiency and MGP on the various markers of
cardiovascular health. In the second section, this review
will outline the clinical impact of dietary and supple-
mental vitamin K2 intake on these outcomes, citing the
data of its use as a novel and practical addition to our
arsenal of cardioprotective therapies.
VITAMIN K-DEPENDENT PROTEINS AND CARDIOVASCULAR
HEALTH
Role of MGP in cardiovascular health
There is a growing body of evidence supporting the vital
role of MGP in cardiovascular disease (CVD).6 This was
first demonstrated in MGP knock- out mice who suffered
premature death within 6–8 weeks after birth consequent
to massive arterial calcification and spontaneous aortic
rupture.7 A paradigm shift around vascular calcifica-
tion has since emerged whereby the previous notion of
a passive, degenerative, and irreversible process is pres-
ently understood as an actively regulated and tenably
preventable or reversible mechanism.1
Figure 1 depicts the mechanism by which vitamin K2
regulates systemic calcification through activation of
MGP in VSMCs and chondrocytes. After the transcrip-
tion and translation of MGP into dp- ucMGP, it under-
goes post- translational modification through two distinct
processes: (1) kinase- mediated serine phosphorylation,1
and (2) γ‐carboxylation of glutamic acid residues medi-
ated by γ‐carboxylase, which requires vitamin K as a
cofactor.2 The latter process is akin to the activation of
several other vitamin- K dependent proteins such as coag-
ulation factors. The resultant active form of MGP, an 84‐
amino acid (approximately 14 kDa) protein, is thought
to protect against soft tissue calcification via several
processes. Calcium apatite is the predominant form of
calcium crystals that accumulate in blood vessel walls, and
it is also commonly found in bone.1 Notably, the process of
vascular calcification resembles bone formation as matrix
vesicles bud from cells and form a nidus for calcification.
In vivo studies have shown that in the absence of activated
MGP, VSMCs differentiate into cells with properties of
chondrocytes and osteoblasts, producing a matrix that
favours calcium crystal deposition.8 MGP regulates calcifi-
cation directly by inhibiting formation and solubilisation
of calcium crystals and through alternative calcification
inhibitors such as fetuin- A, as well as indirectly via modu-
lating transcription factors that suppress differentiation
of VSMC to an osteoblast- like phenotype.9 10 Moreover,
research demonstrates that only the active, carboxyl-
ated form of MGP antagonises the action of pro- calcific
proteins; for instance, it inhibits bone morphogenic
protein- 2 (BMP- 2), a potent pro- osteoblastic protein
heavily expressed in atherosclerotic lesions in states of
inflammation and oxidative stress, which induces an
osteogenic gene expression profile in VSMC.1 9 11
Role of other vitamin K-dependent proteins in cardiovascular
health
It is important to note that there other vitamin K- de-
pendent proteins implicated in cardiovascular health,
including bone Gla protein (or osteocalcin (OC)) and
Gas6 (growth arrest- specific 6) protein.12
The role of OC in cardiovascular health is manifested
by modulation of vascular calcification through activa-
tion of adiponectin, a protein that has been shown to
inhibit osteoblastic differentiation of VSMCs.13 More-
over, OC has been shown to reduce arterial stiffness in
diabetic rat model.14 These findings have been replicated
in human studies, as OC has been shown to be associated
with adiponectin in patients with chronic kidney disease
(CKD).15 A study by Fusaro et al found lower OC levels in
Figure 1 Mechanism of action of vitamin K2. Vitamin
K2 is as a cofactor for gamma- carboxylation of dp-
ucMGP into dp- cMGP in vascular smooth muscle cells
and chondrocytes. dp- cMGP undergoes an additional
phosphorylation by a casein kinase in Golgi bodies into p-
cMGP, the nal active form of MGP that ultimately inhibits
soft tissue calcication. Inactive dp- ucMGP is a biomarker
of poor vitamin K status in the circulation and is associated
with increased deposition of calcium into blood vessels,
predisposing to arterial stiffness via medial calcication and
atherosclerosis via atheroma calcication. On the other hand,
vitamin K- dependent carboxylation activates osteocalcin
(OC), also known as bone Gla protein, and the latter not only
promotes bone growth but also plays a role in preventing soft
tissue calcication through inhibiting calcium and phosphate
precipitation.118 dp- uc, dephospho- uncarboxylated; MGP,
matrix Gla protein.
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Cardiac risk factors and prevention
patients with aortic and iliac calcifications as compared
with patients without calcifications.16 Moreover, in a
prospective study of 774 men aged 51–85 years from the
MINOS cohort who had OC measured at baseline and
were followed over 10 years with serial measurements
of abdominal aortic calcification, higher baseline total
OC was associated with a lower abdominal aortic calci-
fication progression rate (OR=0.74 (0.57 to 0.97) per 10
ng/mL variation; p=0.029) and lower 10- year all- cause
mortality (HR=0.62 (0.44 to 0.86) per 10 ng/mL vari-
ation; p=0.005).17 In light of the above studies, 1 meta-
analysis of 46 studies showed no definitive association of
OC with vascular calcification; it is important to mention,
however, the considerable variability in adjustment for
confounders, heterogeneity of the populations and assays
used for measurement of serum OC in these studies.
Besides, Gas6 protein is a vitamin K- dependent protein
that highly expressed in lungs, hearts and kidneys and
has been shown to regulate calcification of VSMCs.18 19
It has also been shown that androgen receptor signal-
ling inhibits vascular calcification through enhanced
Gas6 transcription.20 Similar findings have been shown
with adiponectin and its effect on vascular calcification
through alterations in Gas6 expression.21 Alternatively,
Gas6 is also known to protect against endothelial dysfunc-
tion and VSMC apoptosis, both of which are mechanisms
that mediate vascular calcification.18 22 Moreover, in
vitro data revealed that phosphate- induced calcification
of VSMC is associated with a downregulation of Gas6
expression.18
Measurement of vitamin K2 levels
In order to investigate the role of vitamin K2 on cardio-
vascular health, a biomarker reflecting vitamin K status is
required. This has been achieved by assessing the status
of vitamin K- dependent proteins that require carboxyl-
ation, and assays measuring MGP seem to be the most
commonly used ones,5 23 24 a measurement that reflects
the bioactivity of vitamin K over a span of weeks to
months.2 25 The assay that quantifies vitamin K deficiency
is that which measures dp- ucMGP.5 With the introduc-
tion and growing adoption of automated commercial
measurements, most notably through the popular, exten-
sively validated kits by ImmunoDiagnostic Systems (IDS,
Boldon, UK), which cost $25 per sample, dp- ucMGP now
serves as an accessible and feasible marker for routine
laboratory assessment in clinical practice.
The following sections will discuss in detail the relation-
ship of vitamin K status with various markers of cardiovas-
cular health.
Arterial stiffness
Plasma dp- ucMGP has consistently shown an association
with measures of central haemodynamics and arterial
function including arterial stiffness, a surrogate marker
of cardiovascular morbidity and mortality. Specifically,
high dp- ucMGP is associated with higher aortic stiff-
ness as assessed by carotid–femoral pulse wave velocity
(PWV),26–29 central pressure28 and augmentation index25
in varying patient populations internationally. A recent
study by Ikari et al found that after 3 months of replacing
warfarin with rivaroxaban, vitamin K deficiency, assessed
by inactive forms of prothrombin and OC, was signif-
icantly reduced (100% to 2% for inactive prothrombin
and 82% to 55% in inactive OC; p<0.05 for both). This
was associated with a significant reduction in arterial stiff-
ness via brachial–ankle PWV.30 The role of active MGP
seems to extend beyond protection from calcification
and is implicated in reduced elastin degradation and
collagen formation in the arterial wall, both of which can
potentially improve arterial stiffness.31
Coronary and vascular calcication
It is well established that MGP inhibits vascular calcifica-
tion. This was first reported in human Keutel syndrome,
which is characterised by systemic vascular calcification
due to loss- of- function mutations in the MGP gene.32
Studies have shown that MGP inhibition of ‘pro-
osteoblastic’ transcription factor BMP- 2 relies on carbox-
ylation.9 Moreover, warfarin, a VKA, has been shown to
accelerate coronary, aortic valvular and mitral annular
calcification (MAC).33 34 Genetic studies have also linked
polymorphism in the gene encoding MGP with vascular
calcification and coronary artery disease (CAD).35 36 The
relationship between low vitamin K status and systemic
calcification in humans has been described in several
studies done on several patient populations. Dalmeijer et
al found a greater trend of coronary artery calcification
(CAC) in postmenopausal women with higher plasma
dp- ucMGP,37 and Liabeuf et al showed a significant asso-
ciation between dp- ucMGP and peripheral arterial calci-
fication score.38 More recently, there are data to suggest
that dp- ucMGP may be associated with higher plaque
stability; in a study on 100 patients undergoing carotid
endarterectomy and histological evaluation of the carotid
plaque, elevated dp- ucMGP was associated with less
plaque haemorrhage, suggesting more plaque stability.39
Valvular calcication
Aortic stenosis (AS) is commonly described as a degen-
erative disease characterised by progressive aortic valve
calcification with no effective medical therapy to delay
its progression available to date. Retrospective work has
linked warfarin use to increased aortic and mitral valve
calcification in humans,34 and observational data suggest
that warfarin is significantly associated with structural
and haemodynamic progression of AS.40 Besides, a multi-
centre observation study on patients with CKD stages
3b–4 and non- valvular atrial fibrillation receiving either
warfarin (n=100) or rivaroxaban (n=247) was conducted
between 2015 and 2017 to assess their differential
impact on valvular calcification measured by echocardi-
ography.41 The study showed that rivaroxaban reduced
both mitral and aortic calcification compared with
warfarin (p<0.001) irrespective of baseline calcification
and confounding factors.
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Both MAC and AS are associated with cardiovascular
morbidity and mortality as well as with calcium deposi-
tion in the aorta and various arterial beds, which may be
localised sequelae of a systemic disease of dysregulated
calcium metabolism.42 Previously described as passive
degeneration, progression of valvular calcification has
recently been identified as an active, potentially modifi-
able process. A cross- sectional study of 839 community
patients with stable CAD found a strong association
between serum inactive total MGP and MAC in those
without diabetes, irrespective of age, renal function,
albumin, C reactive protein (CRP) and traditional CVD
risk factors. This association persisted after adjusting for
calcium, phosphorus and fetuin- A levels.43 Moreover,
polymorphism in MGP gene has been implicated in
progression of aortic calcification in a randomly selected
general population of 296 individuals who participated in
the European Vertebral Osteoporosis Study.44
Measuring inactive forms of MGP, reflecting vitamin
K deficiency, may ultimately prove useful in identifying
individuals at increased risk of cardiac valve disease
progression, and by extension, persons at greater risk
of heart failure (HF) and CVD events. Elucidating the
mechanisms behind valvular calcification may therefore
offer novel insights into CVD.
Microvascular function
The benefits of MGP may also extend to microcirculation
of various tissues. MGP is abundantly expressed in tissues
of the retina,45 kidneys46 and the heart,47 and is postu-
lated to contribute to microvascular integrity of these
organs through anti- calcific and anti- stiffness properties.
In a community study done on 935 randomly recruited
Flemish participants (mean age, 40.9 years; 50.3%
women) and followed over a median of 11 years, higher
dp- ucMGP was associated with a decrease of retinal arte-
riolar diameter,48 which is a prognostic marker of cardio-
vascular outcomes.49
Chronic kidney disease
Markers of vitamin K deficiency have been shown to
be associated with indices of adiposity and inflamma-
tion as well as diabetes and kidney function.12 50 In one
randomised clinical trial, poor vitamin K status as deduced
from low plasma levels of carboxylated OC (cOC) was
associated with a higher fat mass at different body sites
and with waist circumference, while high vitamin K levels
as deduced from high cOC levels were inversely associ-
ated with high- sensitivity CRP, leptin and insulin.51
Vitamin K deficiency, whether measured through
phylloquinone (via uOC assay) or MKs (via dp- ucMGP
assays), is very prevalent in patients with CKD with more
than 60% having some form of vitamin K deficiency.12
Specifically, functional vitamin K deficiency is also prev-
alent among haemodialysis and renal transplant recipi-
ents52 and may, in part, account for their reduced vitamin
K function and increased subsequent risk of vascular
calcification.52 53 Despite improvement in vitamin K levels
following kidney transplantation, vitamin K deficiency as
assessed by dp- ucMGP in kidney transplant patients was
associated with significantly increased risk in all- cause
mortality (HR=3.10; 95% CI: 1.87 to 5.12) among 518
patients with renal transplant followed over a median
follow- up of 9.8 years.54
In regard to renal function, circulating inactive
dp- ucMGP was associated with progression to renal
dysfunction, as assessed by reduction in glomerular filtra-
tion rate (GFR) and presence of microalbuminuria, in
a study on 1009 Flemish subjects who were followed for
a median of 8.9 years.55 To substantiate these findings,
the same investigators studied the histological findings of
kidney biopsies from two healthy kidney donors and four
patients with renal dysfunction.56 They found that tissues
from diseased kidneys but not from healthy kidneys
stained positive for calcium deposits and both carboxyl-
ated and uncarboxylated MGP, suggesting a potential role
of MGP in renal tissue calcification beyond just vascular
calcification. Another cross- sectional analyses of 1166
white Flemish and 352 black South Africans supported
these findings as higher dp- ucMGP was associated with
lower estimated GFR (p≤0.023), and subsequent greater
risk of developing more advanced CKD.57
Besides, patients with end- stage renal disease requiring
haemodialysis are severely vitamin K deficient as evidenced
by higher total MGP.3 One analysis from the VItamin K
Italian (VIKI) dialysis study including 387 patients on
haemodialysis shows that vitamin K2 deficiency, measured
by MK- 4 and MK- 7 serum levels, is significantly associ-
ated with aortic and iliac arterial calcification (OR=2.82
and 1.61, respectively; p<0.05).58 Another study of 842
patients with stable coronary disease in the community
setting demonstrated a direct association between GFR
and serum levels of inactive, ucMGP after adjusting for
confounders.59 Further, MGP has been correlated with
serum creatinine in those with HF and CKD.60 61 In a sepa-
rate study by Kurnatowska et al that investigated 38 non-
dialysed Caucasian non- smokers aged 18–70 years with
CKD stages 4–5 who were supplemented with vitamin K2,
plasma dp- ucMGP was positively associated with protein-
uria, serum creatinine, parathyroid hormone (PTH) and
fibroblast growth factor 23 (FGF- 23), and inversely asso-
ciated with GFR.61
Cardiac microcirculation
From the perspective of cardiac microcirculation, Paulus
and Tschöpe proposed a novel theory surrounding
left ventricular (LV) diastolic dysfunction that shifted
emphasis from LV afterload to inflammation of the coro-
nary microcirculation,62 ultimately implicating MGP in
the disease process. In one study of over 900 Flemish
and Swiss patients, dp- ucMGP correlated with diastolic
dysfunction as assessed by increased LV filling pressures
and higher E/e’ ratio.47 In this study, cardiac biopsies of
ischaemic or dilated cardiomyopathy and healthy hearts
(n=4 for each) were stained with conformation- specific
MGP antibodies. The authors found a higher prevalence
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Cardiac risk factors and prevention
of uncarboxylated inactive, dp- ucMGP in the perivascular
matrix and interstitium of diseased relative to normal
hearts (p≤0.004), concluding that activated MGP is an
ubiquitous, locally acting molecule that protects the
microcirculation and perivascular matrix from injury
caused by calcium deposition by sequestering intracel-
lular calcium, thereby preserving LV diastolic function.
HF measures and mortality
Patients with symptomatic AS frequently develop LV
outflow obstruction and LV hypertrophy as a compensa-
tory mechanism to maintain the ejection performance.
In light of the dramatic increase in mortality rate after
symptom onset, aortic valve replacement is recom-
mended in symptomatic patients with AS.
It is well founded that circulating dp‐ucMGP levels
play a role in both systolic and diastolic cardiac function
and their associated effects on mortality. In two Norwe-
gian studies, significant associations were found between
higher plasma dp- ucMGP and unfavourable echocar-
diographic measures and mortality among patients
with severe AS and chronic heart (HF).60 63 Among 147
patients with symptomatic AS, dp‐ucMGP was signifi-
cantly higher in diseased patients compared with healthy
sex- matched and age- matched controls. Moreover, levels
of dp- ucMGP were significantly correlated with neuro-
hormonal (N- terminal pro- brain natriuretic peptide
(NT‐proBNP)) and haemodynamic markers (LV ejec-
tion fraction and cardiac index) of HF severity in non-
warfarin users, and with NT‐proBNP in warfarin users.
Importantly, higher dp‐ucMGP concentration correlated
with all‐cause mortality (HR ~7) after a mean follow‐up of
23 months,63 suggesting that a dysregulated MGP system
may play a role in the development of LV hypertrophy and
HF mortality in these patients. Moreover in this study, the
risk of mortality was highest in patients who underwent
aortic valve replacement. This confers a tenable role for
dp‐ucMGP not only in untreated patients with symptom-
atic AS, but additionally as a pre‐procedural marker for
long‐term risk evaluation in patients who undergo aortic
valve replacement. The second study found that among
179 patients with chronic systolic and diastolic HF,
increased dp- ucMGP was associated with greater disease
severity compared with healthy age- matched and sex-
matched controls. Elevated dp- ucMGP further correlated
with increased CRP, NT- proBNP, systolic (LV ejection
fraction) and diastolic dysfunction, and ischaemia as the
aetiology for HF.60 After a mean 2.9 years, patients in the
highest tertial of dp- ucMGP level had increased all- cause
mortality, and dp- ucMGP was markedly higher in those
who died due to HF progression.
From a pathophysiological perspective, the MGP system
may serve both direct and indirect roles in the cellular
processes associated with myocardial remodelling and
the development and progression of HF. The absence of
myocardial calcification in MGP- deficient mice7 implies
possible interplay between MGP and cardiac haemody-
namics unrelated to inhibition of calcification. Elevated
MGP levels are seen during rapid myocardial response
to pressure overload, potentially induced by angio-
tensin II, suggesting a relationship between neurohor-
monal maladaptive responses and MGP.64–66 Prior DNA
microarray animal and human studies have demon-
strated increased mRNA expression of MGP in the LV
during acute and chronic pressure overload64 67 and in
experimental HF in rats and mice.65 68 Moreover, studies
have demonstrated that MGP anchors to the extracellular
matrix by binding to vitronectin, which may have modi-
fying effects on members of the transforming growth
factor β family that influence cardiac remodelling during
HF.69 Most recently, Mustonen et al66 showed that following
a myocardial infarction, MGP is rapidly upregulated in
response to cardiac overload long before the develop-
ment of LV hypertrophy and remodelling. While the
precise mechanism remains unclear, there is increasing
plausibility that plasma dp‐ucMGP and valvular calcifica-
tion are vital in cardiac dysfunction among patients with
AS.
Cardiovascular morbidity and mortality
Accumulating evidence highlights a relationship between
a low state of circulating vitamin K, signified by elevated
dp- ucMGP, and the development and progression of CVD
and mortality.24 Studies from Norway and Czech Republic
demonstrate a strong association between higher plasma
dp- ucMGP and risk of all- cause mortality.60 63 70 Notably,
two Mendelian randomisation studies found that lower
genetically predicted dp- ucMGP was causally associated
with cardiovascular risk4 and mortality.71
A prospective study over a mean 5.6 years in an elderly
population found that high plasma dp- ucMGP concentra-
tions correlated with an increased risk of incident CVD,
defined as one or more of coronary heart disease, periph-
eral arterial disease and CAD, independent of traditional
cardiac risk factors and vitamin D status.72 Another
investigation showed that elevated dp- ucMGP was asso-
ciated with an increased hazard of incident CVD (CAD,
peripheral artery disease, HF and stroke) after a median
follow- up of 11.2 years among 518 patients with type 2
diabetes.73 Additionally, Mayer et al found that among 799
patients with past myocardial infarction, coronary revas-
cularisation, or first ischaemic stroke, increased plasma
dp- ucMGP conferred an elevated risk of both all- cause
and cardiovascular mortality at 5 years, despite adjusting
for potential confounders.70 In a subsequent subcohort
analysis of patients with HF within this population, high
dp- ucMGP was associated with 5- year all- cause mortality,
with the largest HR found among those with elevated
BNP (>100 ng/L).74 More recently, the role of dp- ucMGP
on cardiovascular outcomes was studied in 894 patients
with ischaemic heart disease (at least 6 months after they
had myocardial infarction and/or coronary revasculari-
sation); high dp- ucMGP was significantly associated with
2.4 and 3.5 higher risk of 5- year all- cause and cardiovas-
cular mortality, respectively.75
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These studies stand in contrast with a prospective
case–cohort investigation from the European Prospective
Investigation Into Cancer and Nutrition–Netherlands
(EPIC- NL) Study which failed to reveal an association
between high dp- ucMGP and increased CVD or stroke
after a mean 11.5 years.73 Similarly, in the Health ABC
Study where plasma vitamin K1 (phylloquinone) and
dp- ucMGP were measured in 1061 participants free
of CVD (aged 70–79 years) who are followed for over
12 years, the authors did not show an association with
either markers of vitamin K and incident CVD; however,
in a subset of subjects with treated hypertension, low
plasma phylloquinone was associated with higher CVD
risk overall (HR= 2.94; 95% CI: 1.41 to 6.13).76 Notwith-
standing, a recent meta- analysis aimed in assessing the
prospective association between vitamin K2 and CVD
and all- cause mortality importantly identified a relation-
ship between elevated plasma dp- ucMGP and all- cause
mortality (pooled HR=1.84, 95% CI: 1.48 to 2.28; five
studies) and cardiovascular mortality (pooled HR=1.96,
95% CI: 1.47 to 2.61; two studies).6
It remains evident that vitamin K deficiency is strongly
associated with several markers of cardiovascular health,
and plasma MGP represents a clinically feasible and
sensitive tool to assess for such deficiency. Moreover,
measuring inactive MGP is a powerful biomarker that can
be incorporated in clinical and translational research,
particularly for investigating calcification, HF and arterial
stiffness. Whether intake of vitamin K2 through supple-
mentation or diet has the potential to reduce the risk of
such cardiovascular outcomes will be further discussed in
the next sections.
Vitamin K2 and cardiovascular health
The literature surrounding vitamin K2 dates to its
discovery in the 1930s and identification of its molecular
mechanisms in the 1970s,77 and continues to grow after
the recent discovery of the role of active MGP on vitamin
K- dependent vascular calcification. Notwithstanding the
breadth of research, an organised and succinct under-
standing of its cardiovascular role remains limited. The
following sections provide a comprehensive but concise
overview of the evidence related to the cardiovascular
benefits of vitamin K2 intake through diet and supple-
mentation.
Dietary intake
Vitamin K is a fat- soluble vitamin found in two forms: (1)
phylloquinones (vitamin K1), present in leafy green vege-
tables and responsible for mediating coagulation, and
(2) MKs (vitamin K2), present in fermented food and
implicated in systemic calcification.78 Its pattern of bodily
distribution appears tissue specific.79 While vitamin K1
concentrates in the liver where it regulates the produc-
tion of coagulation factors, vitamin K2 is found in extra-
hepatic tissues such as bones and arteries.79 Long- chain
MKs (ie, MK- 7) are transported more efficiently to extra-
hepatic tissues.78 80
Intake of vitamin K2 through diet alone is seemingly
inadequate for complete activation of MGP in humans.81
MK- 7 is in relatively low abundance in Western diets as it
is commonly found in a variety of fermented foods such
as natto and, to a much lesser extent, meats and dairy
products.78 82 Among a subcohort of 4275 subjects from
the Prevention of Renal and Vascular End- stage Disease
(PREVEND) Study, 31% had functional vitamin K insuf-
ficiency (ie, dp- ucMGP >500 pmol/L).83 Children and
those over 40 years of age are mostly vitamin K deficient
as measured by dp- ucMGP.84 Human studies have shown
that high vitamin K2 intake is associated with reduced
coronary artery calcification and CVD risk, and those
effects are thought to be mediated by increased activa-
tion of MGP.85–87 For example, intake of natto, which is
a vitamin K2- rich food common in the Japanese popula-
tion, has been shown to be associated with lower hazard
of CVD mortality (HR=0.75, p trend=0.0004) in a large
Japanese cohort study of 13 355 men and 15 724 women,
followed over 16 years.88
Oral supplementation
The effective recommended dose of longer chain MKs
(MK- 7, MK- 8 and MK- 9) for cardiovascular health benefits
is 180–360 µg/day.89 90 Epidemiological evidence suggests
that intake of vitamin K1 and K2 reduces cardiovascular
and overall mortality.91 A substantial portion of ingested
vitamin K1 is converted into K2, which in turn accumu-
lates within the extrahepatic tissues. Studies of vitamin K1
supplementation used markedly higher doses (1–2 mg/
day) than vitamin K2, especially MK- 7 (180–360 µ/day),
most likely due to the predominant extrahepatic activity
and vascular tissue specificity of vitamin K2 relative to K1.
Both isotypes are potentially comparable in their overall
health effects, yet the higher vascular- specific activity of
vitamin K2 may make it increasingly appealing as an effi-
cacious option for utilisation in cardiovascular outcomes
studies. Supplementing vitamin K2 is also promising in
its ability to replete plasma stores of vitamin K2 and ulti-
mately sustain an optimal level for inhibiting calcification.
Supplementation has previously been associated with a
dose- dependent reduction in circulating dp- ucMGP,82 92
and an ensuing improvement in arterial stiffness among
healthy adults and those with end- stage renal disease
requiring haemodialysis.26 81 In a supplementary analysis,
MK- 7 was well tolerated in failing to cause a hypercoag-
ulable state.89 There have been no documented cases
of toxicity of vitamin K1, MK- 4 or MK- 7. Additionally,
the WHO has set no upper tolerance level for vitamin K
intake.93
Cardiovascular risk factors
The following sections will discuss the influence of vitamin
K, specifically focusing on vitamin K2, on various cardio-
vascular risk factors, including arterial stiffness, endothe-
lial dysfunction, cardiac output, diabetes mellitus, valvular
and vascular calcification, and cardiovascular mortality
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Cardiac risk factors and prevention
(figure 2). All the published studies in those fields are
presented in table 1.
Arterial stiffness and endothelial dysfunction
Both vitamin K1 and MK- 7 reduce arterial stiffness and
improve elastic properties of the carotid artery.94 MK- 7
supplementation improves arterial stiffness in healthy
adults95 postmenopausal women,90 patients with CAD96
and renal transplant recipients,27 as measured by PWV.
It is also thought that the protective effects of vitamin
K2 on cardiovascular mortality may be related to the
vitamin K- dependent regulation of endothelial func-
tion.83 Endothelial dysfunction, defined as impaired
endothelium- dependent vasodilation, is a significant
predictor of adverse cardiovascular outcomes.97 Evidence
from a recent study reveals that in genetically driven mice
models of high hypercholesterolaemia (ApoE/LDLR−/−),
K2- MK- 7 improves nitric oxide- dependent endothelial
function, assessed by MRI of the flow- mediated dilation,
vascular response to acetylcholine administration and
endothelial nitric oxide synthase- dependent nitric oxide
production.98 Moreover, MGP has been shown in animal
models to inhibit osteogenic properties of vascular
endothelial cells that is driven by BMP signalling.99
Cardiac output
The role of vitamin K2 in mitochondrial function is medi-
ated by its production of mitochondrial ATP, which has
direct implications for contractile muscles (ie, cardiac)
that are comprised of abundant mitochondria.100 Intake
of vitamin K2 has been associated with increased cardiac
output, stroke volume and heart rate, and decreased
blood lactate.101 These effects are consistent with the
greater maximal cardiovascular performance seen with
oral vitamin K2 supplementation.
Metabolic syndrome
Several studies have examined the relationship between
vitamin K2 intake and indices of type 2 diabetes mellitus, a
major risk factor for CVD. From a large prospective study
of 38 094 Dutch individuals (aged 20–70 years), Beulens
et al revealed that dietary MK intake (10 µg increment
increase) was inversely associated (p=0.04) with inci-
dence of type 2 diabetes.102 In a randomised clinical trial,
Choi et al demonstrated that 4 weeks of supplementing
30 mg/day of vitamin K2 (menatetrenone) significantly
increased the insulin sensitivity index (p=0.01) and dispo-
sition index (p<0.01) compared with placebo in healthy
young men.103 The benefits of vitamin K2 extend beyond
direct effect on type 2 diabetes as it has been recently
shown, in a randomised placebo- controlled trial on 214
postmenopausal healthy women receiving 180 µg/day of
vitamin K2 (MK- 7) or placebo, to have favourable effect
on obesity with reduction in abdominal and visceral fat
among those who responded well to MK- 7 (manifested
through elevated of cOC).51
Vascular and valvular calcication
Anticoagulation- mediated inhibition of vitamin K metab-
olism has been associated with progression of both
vascular and valvular calcification. Animal studies have
found increased arterial and soft tissue calcification as
a result of inhibition of vitamin K- dependent proteins
by VKA.33 80 Long- term VKA use is associated with both
coronary and extracoronary vascular calcification in
humans.104 105 Sønderskov et al recently demonstrated
that among 14 604 participants within the Danish Cardi-
ovascular Screening (DANCAVAS) trial, VKA use was
associated with progression of aortic valve calcification,
evidenced by a 6% increase in calcification with each year
of treatment.106 These results remained consistent after
a sensitivity analysis excluding patients with cardiac risk
factors on statins showed no progression of calcification
in those taking direct oral anticoagulants.
Vitamin K supplementation may delay the progression
of aortic valve calcification. In a rat model, warfarin-
induced arterial calcification and arterial stiffness,
where inactive MGP was highly expressed, appeared to
regress with a diet rich in vitamin K.80 The first in- human
randomised control trial recently found that among a
small cohort of 99 patients with AS, vitamin K1 intake (2
mg daily) decelerated the progression of CT- based aortic
valvular calcification compared with placebo (10% vs
22%, respectively; p=0.04).107 It is important to note that
27 patients (12 vitamin K1, 15 placebo) dropped out of
the study.
Vitamin K supplementation may also potentially
target vascular calcification. Vitamin K2 intake has been
Figure 2 Role of vitamin K2 on various measures of
cardiovascular health. Based on a myriad of preclinical,
epidemiological and interventional studies, vitamin K2 has
been shown to have strong potential in reducing several
surrogate measures of cardiovascular morbidity and
mortality, including arterial stiffness, valvular calcication,
arterial calcication, cardiac systolic and diastolic functions.
In light of such evidence, vitamin K2 has been strongly
associated with improved cardiovascular health by improving
arterial, endothelial and myocardial function and with
potential for improved overall survival.
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Table 1 Role of vitamin K on markers of CVD
Study Sample size Patient population Study methods Study ndings
Arterial stiffness
Braam et al94 181 Healthy postmenopausal
Caucasians between 50 and 60
years of age
Sex: female only
Age: 55
Design: double- blind RCT
Intervention: vitamin D3 (8 µg)
+K1 (1 mg) supplementation
Follow- up (years): 3
↑
Distensibility (+8.8%,
p<0.05)
↑
Compliance (+8.6%, p<0.05)
↓
Pulse pressure (−6.3%,
p<0.05)
↓
CCA elasticity (−13.2%,
p<0.01)
Knapen et al90 244 Healthy, postmenopausal subjects
aged 55–65 years
Sex: female only
Age: 60
Design: double- blind RCT
Intervention: vitamin K2 (MK- 7)
supplementation (180 µg)
Follow- up (years): 3
↓
Carotid–femoral PWV
↓
Stiffness Index β
(p<0.02)
Ikari et al96 26 Patients with coronary
calcication and at least 1
coronary risk factor
Sex: 65% female
Age: 69
Design: open- label, single arm
Intervention: vitamin K2 (MK- 4)
supplementation (45 mg)
Follow- up (years): 1
↓
Brachial–ankle PWV by 18%
only in patients with vitamin K2
deciency (p=0.03)
Mansour et al27 60 Adult renal transplant recipients
with functioning graft for≥3
months
Sex: 43% female
Age: 50
Design: prospective, single-
centre, single- arm trial
Intervention: vitamin K2 (MK- 7)
supplementation (360 µg)
Follow- up (weeks): 8
↓
Mean carotid–femoral PWV
by 14.2% (p<0.001)
Vermeer and Hogne95 243 Healthy adults without a history
of cardiovascular disease
Sex: 54%
Age: 61
Design: double- blind, placebo-
controlled RCT
Intervention: vitamin K2 (MK- 7)
supplementation (180 µg)
Follow- up (years): 1
↑
Mean carotid–femoral PWV in
placebo group (p<0.005) but
no signicant change in MK- 7
group
Cardiac output
McFarlin et al101 26 Aerobically trained athletes with
normal body composition
Sex: 31% male
Age: 21
Design: double- blind RCT
Intervention: vitamin K2
supplementation (300 mg for
4 weeks, then 150 mg for 4
weeks)
Follow- up (weeks): 8
↑
Maximal cardiac output by
12% (p=0.03)
Metabolic syndrome
Beulens et al102 38 094 Dutch subjects without diabetes
aged 20–70 years from the
Prospect- EPIC and MORGEN- EPIC
cohorts (1993–1997)
Sex: 26% male
Age: 49
Design: prospective,
population- based cohort study
Intervention: dietary vitamin K1
and K2 intake using FFQ
Follow- up (years): 10
↓
Risk of incident type 2
diabetes with 10 µg increment
increase in dietary vitamin K2
intake
(HR=0.93, p=0.04)
Choi et al103 42 Healthy young volunteers
Sex: Male only
Age (median): 29
Design: Placebo- controlled trial
Intervention: vitamin K2
supplementation (30 mg)
Follow- up (weeks): 4
↑
Insulin sensitivity index
(p=0.01)
↑
Disposition index (p<0.01)
↑
cOC (p=0.01)
Asemi et al119 66 Overweight patients with diabetes
with CHD, aged 40–85 years,
living in Iran
Sex: 47% female
Age: 65
Design: Double- blind RCT
Intervention: vitamin D (5 µg)
+K (90 µg)+calcium (500 mg)
supplementation
Follow- up (weeks): 12
↓
Maximum carotid intima
media thickness (p=0.02)
↓
HOMA- IR (p=0.01)
↓
HOMA- B (p=0.01)
↑
QUICKI (p=0.01)
Knapen et al51 214 Healthy, postmenopausal women
Sex: female only
Age: 55–65
Design: randomised, placebo-
controlled trial
Intervention: vitamin K2 (MK- 7)
180 µg/day or placebo
Follow- up (years): 3
Only in good responders (
↑
cOC):
↑
Total and HMW adiponectin
↓
Abdominal fat mass (waist
circumference and VAT)
Continued
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Cardiac risk factors and prevention
Study Sample size Patient population Study methods Study ndings
Vascular calcication
Beulens et al85 564 Healthy Dutch subjects aged
49–70 years not on HRT or
contraceptives, sampled (2002–
2004) from the PROSPECT- EPIC
Study
Sex: female only
Age: 67
Design: population- based,
cross- sectional study
Intervention: vitamin K1 and
K2 (MK- 4–MK- 10) intake using
FFQ
Follow- up:
↓
Coronary calcication with
MK intake only
(RR=0.80 (0.65 to 0.98), p
trend=0.03)
Shea et al86 388 Asymptomatic, ambulatory
community- dwelling subjects
aged 60–80 years
Sex: 60% female
Age: 68
Design: double- blind RCT
Intervention: vitamin K1
supplementation (500 µg)
Follow- up (years): 3
↓
CAC progression in
those>85% adherent to
supplementation (p=0.03)
Fusaro et al58 387 Patients on haemodialysis for≥1
year
Sex: 37% female
Age: 64
Design: prospective
observational study
Comparison groups: patients
with or without vitamin K1 or
vitamin K2 (MK- 4, MK- 5 or MK-
7) deciency
Follow- up (years): 3
↑
Risk of abdominal aortic
calcication with MK- 4
deciency (OR=2.8, p=0.026)
↑
Risk of iliac calcication with
MK- 7 deciency (OR=1.6,
p=0.042)
Kurnatowska et al120 42 Non- smoking, non- dialysed
Caucasians with CKD stages
3–5, stable renal function for≥6
months and CAC ≥10 AU
Sex: 48% female
Age: 58
Design: double- blind RCT
Intervention: vitamins K2
(MK- 7, 90 µg)+D3 (10 µg) vs D3
(10 µg)
Follow- up (months): 9
↓
Change in CCA intima-
media thickness in vitamin
K2+D group (0.06±0.08 vs
0.14±0.05 mm, p=0.005)
Nonsignicant decrease in
ΔCAC score in K2+D group
(p=0.7)
Ikari et al96 26 Patients with coronary
calcication and at least 1
coronary risk factor
Sex: 65% female
Age: 69
Design: open- label, single arm
Intervention: vitamin K2 (MK- 4)
supplementation (45 mg)
Follow- up (years): 1
↑
CAC score by 14% (p=0.02)
Zwakenberg et al110 68 Subjects aged>40 years with
CVD, type 2 diabetes, and
eGFR>30
Sex: 24% female
Age: 69
Design: double- blind RCT
Intervention: vitamin K2 (MK- 7)
supplementation (360 µg)
Follow- up (months): 6
No change in femoral
arterial calcication on18F-
NaF PET scan (p=0.06) or
CT scan (p=0.18)
Oikonomaki et al109 102 Adults with ESRD on
haemodialysis
Sex: not specied
Age: 67
Design: prospective,
randomised, open- label clinical
trial
Intervention: vitamin K2
supplementation (200 µg)
Follow- up (years): 1
No change in abdominal aortic
calcication via CT- measured
Agatston score
De Vriese et al108 132 Chronic haemodialysis patients
with non- valvular atrial brillation
and CHA2DS2- VASc score≥2
Sex: 33% female
Age: 80
Design: multicentre,
prospective, randomised, open-
label trial
Intervention: VKA
vs rivaroxaban vs
rivaroxaban+vitamin K2 (2000
µg three times per week)
Follow- up (months): 18
No differences in change
of PWV or coronary artery,
thoracic aorta, or cardiac valve
calcium scores at follow- up,
or all- cause death, stroke or
cardiovascular events between
groups
Bartstra et al111 68 Subjects aged>40 years with
CVD, type 2 diabetes, and
eGFR>30
Sex: 24% female
Age: 69
Design: post- hoc analysis of
double- blind RCT
Intervention: vitamin K2 (MK- 7)
supplementation (360 µg)
Follow- up (months): 6
No change in total arterial
calcication, assessed by
CT scan in several large
arterial beds
Table 1 Continued
Continued
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10 Hariri E, etal. Open Heart 2021;8:e001715. doi:10.1136/openhrt-2021-001715
inversely correlated with CAC in healthy elderly individ-
uals.91 Further, vitamin K1 slowed the progression of CAC
at 3- year follow- up.86 Yet, despite a significant reduction
in dp- ucMGP, two recent studies failed to demonstrate a
change in aortic calcification scores with vitamin K2 supple-
mentation in those on haemodialysis with or without
anticoagulation.108 109 In one double- blind, placebo-
controlled trial by Zwakenberg et al, 68 patients with type
2 diabetes mellitus were randomised to receive 360 µg/
day of vitamin K2 (MK- 7) or placebo for 6 months,110
and there was no significant difference in femoral arte-
rial calcification measured by either 18sodium fluoride
positron emission tomography (primary outcome) or
CT scan (secondary outcome). A post- hoc analysis of
this trial was recently published to investigate the effect
of vitamin K2 on CT- based arterial calcification mass,
quantified in several large arterial beds, and there was
no significant difference between placebo and supple-
mented groups.111 Both studies were limited by the short
duration of follow- up, small sample size, low percentage
of severe vitamin K deficiency and high dropout rates.
Despite the evident potential of vitamin K2 in modulating
vascular and valvular calcification, its definitive role is yet
to be fully established.
Cardiovascular morbidity and mortality
Table 2 summarises the studies to date of vitamin K
intake and cardiovascular mortality. The first to report on
dietary intake of vitamin K2, the prospective Rotterdam
study recruited 4807 subjects with dietary data and no
history of myocardial infarction between 1990 and 1993,
and followed patients until January 2020. The authors
stratified groups by quartiles of increasing vitamin K2
intake, and found that the upper tertials of vitamin K2 but
not K1 intake was inversely associated with severe aortic
calcification (OR=0.48) as well as cardiovascular (rela-
tive risk (RR)=0.43) and all- cause (RR=0.74) mortality.
These findings persisted after adjusting for traditional
risk factors and dietary factors.91 In another prospec-
tive cohort study inclusive of women aged 49–70 years
without prior CVD who were enrolled between 1993
and 1997 as part of the European Prospect- EPIC cohort
(mean follow- up of 8.1±1.6 years), vitamin K2 but not K1
intake was significantly and inversely associated with risk
of incident CAD (HR=0.9 per 10 µg/day of vitamin K2
intake).87 These findings were consistent with a prospec-
tive Norwegian study that followed 2987 healthy subjects
for a median of 11 years and demonstrated an associa-
tion between vitamin K2 but not K1 and reduced CAD risk
(HR=0.52, 95% CI: 0.29 to 0.94, p trend=0.03).112 More-
over, a separate prospective investigation of 40 087 men
from the Health Professionals’ Follow- up Study from
1986 to 2000 found a significant trend (RR=0.84, p=0.05)
towards a lower incidence of total CAD with increasing
intake of food rich in vitamin K1.113
In the prospective PREDIMED (Prevención con Dieta
Mediterránea) Study, the authors investigated the impact
of dietary vitamin K1 and K2 on all- cause mortality among
7216 participants who were followed for a median of 4.8
years.114 They found a significant and inverse relationship
between dietary vitamin K1 intake and risk of all- cause
mortality after controlling for potential confounders
(HR=0.64, 95% CI: 0.45 to 0.90). On longitudinal assess-
ment, those who increased their intake of vitamin K1 or
vitamin K2 had a lower risk of all- cause mortality (HR=0.57
and HR=0.55, respectively) relative to those with reduced
or stable intake. These findings are in line with those of
Study Sample size Patient population Study methods Study ndings
Valvular calcication
Geleijnse et al91 4807 Dutch subjects >55 years without
prior MI at baseline (1990–1993)
Sex: 38% male
Age: 67
Design: prospective,
population- based
Intervention: dietary vitamin K1
and K2 using FFQ
Follow- up (years): 7
↓
Severe aortic calcication
in mid and upper tertials of
vitamin K2 intake (OR=0.71
and 0.48, respectively;
p<0.05)
Brandenburg et al107 99 Asymptomatic or mildly
symptomatic patients without
CKD with aortic valve PFV>2 m/s
Sex: 82% male
Age: 69
Design: prospective, single-
centre, open- label RCT
Intervention: vitamin K1
supplementation (2 mg)
Follow- up (years): 1
↓
Progression in aortic valve
calcication volume score
(10% vs 22%, p=0.04)
Both ages and follow- up times are presented as mean years, unless otherwise specied, and rounded to the nearest whole number. All RCT
study designs are placebo controlled unless otherwise specied. All provided dosages are per daily unless otherwise noted. P values <0.05
denote signicance.
AU, Agtston units; CAC, coronary artery calcication; CCA, common carotid artery; CHD, coronary heart disease; CKD, chronic kidney
disease; cOC, carboxylated osteocalcin; CVD, cardiovascular disease; eGFR, estimated glomerular ltration rate; ESRD, end- stage renal
disease; FFQ, Food Frequency Questionnaire; 18F- NaF PET, 18sodium uoride positron emission tomography; HMW, human molecular
weight; HOMA- B, homeostasis model for assessment of B- cell function; HOMA- IR, homeostasis model for assessment of insulin resistance;
HRT, hormone replacement therapy; MI, myocardial infarction; MK, menaquinone; N/A, not applicable; PFV, peak ow velocity; PWV, pulse
wave velocity; QUICKI, quantitative insulin sensitivity check index; RCT, randomised control trial; RR, relative risk; VAT, estimated visceral
adipose tissue area; VKA, vitamin K antagonist.
Table 1 Continued
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Cardiac risk factors and prevention
patients with CKD who were followed for a median of
13.3 years as part of the National Health and Nutrition
Examination Survey III registry (HR=0.78, 95% CI: 0.64
to 95, p=0.016).115 A recent meta- analysis concluded that
higher dietary consumption of vitamin K1 and K2 is associ-
ated with a lower risk of CAD (pooled HR=0.92, 95% CI:
0.84 to 0.99 and HR=0.70, 95% CI: 0.53 to 0.93, respec-
tively), but has no correlation with all- cause mortality,
CVD mortality or stroke.6
Conclusions and future directions
This review covers the rapidly expanding evidence
supporting the cardioprotective effects of vitamin K2
intake. Mediated by activated MGP, the benefits of
vitamin K2 extend beyond calcification homeostasis and
antagonism, and may further include preventing or
slowing the progression of arterial stiffness, endothelial
dysfunction, diabetes and HF. Moreover, vitamin K2
supplementation appears safe and practical, and its use
can be readily investigated in randomised clinical trials.
Although the data presented in this review are encour-
aging, most of the included studies were limited by their
non- randomised design, heterogeneity in results, variable
dosages and formulations of vitamin K used, small sample
sizes, short duration of follow- up and restricted ability to
accurately assess vitamin K intake, in turn precluding
our ability to infer causality of clinical endpoints. With
evidence mounting, the definitive role of vitamin K2
supplementation in delaying progression of vascular
and valvular calcification remains the subject of multiple
randomised clinical trials.116 117 Nonetheless, the utility of
vitamin K2 and MGP in various patient populations such
as those with valvular heart disease and cardiomyopathy
Table 2 Association of dietary vitamin K intake with coronary disease and cardiovascular mortality
Study
Sample
size Patient population Study methods Study ndings
Geleijnse et al91 4807 Dutch subjects >55 years without prior MI at
baseline (1990–1993)
Sex: 38% male
Age: 67
Design: prospective, population- based
Intervention: vitamin K1 and K2 using
FFQ
Follow- up (years): 7
↓
Cardiovascular mortality (RR=0.43
(0.24 to 0.77)) and all- cause
mortality (RR=0.74 (0.59 to 0.92))
with K2 but not K1 in upper tertials of
energy- adjusted intake
Erkkilä et al113 40 087 Healthcare workers aged 40–75 years,
free of CVD, stroke and cancer at baseline
(1986–2000)
Sex: male only
Age: 53
Design: prospective, population- based
Intervention: vitamin K1 using FFQ
Follow- up (years): 14
↓
Incidence of total CAD (RR=0.84, p
trend=0.05)
Gast et al87 16 057 Subjects aged 49–70 years free of CVD,
recruited from the European Prospect- EPIC
cohort (1993–1997)
Sex: female only
Age: 67
Design: prospective, population- based
Intervention: vitamin K2 (subtypes MK-
7–9) using FFQ
Follow- up (years): 8
↓
Risk of incident CAD (HR=0.91
(0.85 to 1.00))
Juanola- Falgarona et al114 7216 Community- dwelling adults enrolled in
PREDIMED trial, without baseline CVD but with
either type 2 diabetes or≥3 cardiovascular risk
factors
Sex: 57% female
Age: 67
Design: prospective, population- based
Intervention: dietary vitamin K1 and K2
(subtypes MK- 7–9) using FFQ
Follow- up (years): 5
↓
All- cause mortality with increasing
intake of vitamin K1 or K2 (HR=0.57
and HR=0.55, respectively; p<0.05)
Cheung et al115 3401 Non- hospitalised participants ≥20 years of
age with CKD from the NHANES III Study
(1988–1994)
Sex: 67% female
Age: 62
Design: prospective, population- based
Intervention: vitamin K1 and K2 using
24- hour dietary recall
Follow- up (years): 13
↓
All- cause (HR=0.85 (0.72 to
1), p=0.047) and CVD mortality
(HR=0.78 (0.64 to 0.95), p=0.016)
Zwakenberg et al121 33 289 Dutch subjects aged 20–70 years without
baseline CVD, diabetes or cancer recruited from
the EPIC- NL cohort (1993–1997)
Sex: 26% male
Age: 49
Design: prospective, population- based
Intervention: vitamin K1 and K2 using
FFQ
Follow- up (years): 17
Borderline
↓
CHD mortality with
higher long chain vitamin K2
intake (HR=0.86 (0.74 to 1.00), p
trend=0.06)
No association of vitamin K1 or K2
with CVD or all- cause mortality
Haugsgjerd et al112 2987 Healthy Norwegian subjects aged 46–49
years without baseline CAD recruited from the
Hordaland Health Study (1997–1999)
Sex: 57% female
Age: 48
Design: prospective, population- based
Intervention: vitamin K1 and K2 using
FFQ
Follow- up (years): 11
↓
Risk of incident CAD with higher
vitamin K2 but not K1 (HR=0.52, p
trend=0.03), attenuated by adjusting
for dietary confounders (HR=0.58, p
trend=0.16)
Both ages and follow- up times are presented as mean years, or median years in Cheung et al115 and rounded to the nearest whole number. P values
<0.05 denote signicance.
CAD, coronary artery disease; CHD, coronary heart disease; CKD, chronic kidney disease; CVD, cardiovascular disease; FFQ, Food Frequency
Questionnaire; MI, myocardial infarction; MK, menaquinone; NHANES III, National Health and Nutrition Examination Survey; RR, relative risk.
on November 16, 2021 by guest. Protected by copyright.http://openheart.bmj.com/Open Heart: first published as 10.1136/openhrt-2021-001715 on 16 November 2021. Downloaded from
Open Heart
12 Hariri E, etal. Open Heart 2021;8:e001715. doi:10.1136/openhrt-2021-001715
grows commensurate the data supporting its efficacy in
improving cardiac function and decelerating arterial stiff-
ness.
Twitter Nicholas Kassis @kassisMD
Contributors EH conceived and designed the study. EH, NK, J- PI and AS collected,
analysed and interpreted the data, and performed the literature review. EH, NK
and J- PI drafted the manuscript and designed the tables. LJS, TI, SCH, AB and SK
revised the manuscript. OA designed the gures. TI, SCH and SK supervised the
study. All authors have read and approved the manuscript.
Funding This study was made possible by a generous gift from Jennifer and Robert
McNeil as unrestricted philanthropic support to the Heart and Vascular Institute,
Cleveland Clinic.
Disclaimer The funding source had no role in the design or conduct of the study;
collection, or interpretation of the data; preparation, review, or approval of the
manuscript; or decision to submit the manuscript for publication.
Competing interests LJS received an institutional grant from NattoPharma.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data sharing not applicable as no datasets generated
and/or analysed for this study.
Open access This is an open access article distributed in accordance with the
Creative Commons Attribution Non Commercial (CC BY- NC 4.0) license, which
permits others to distribute, remix, adapt, build upon this work non- commercially,
and license their derivative works on different terms, provided the original work is
properly cited, appropriate credit is given, any changes made indicated, and the use
is non- commercial. See:http:// creativecommons. org/ licenses/ by- nc/ 4. 0/.
ORCID iDs
NicholasKassis http:// orcid. org/ 0000- 0002- 7975- 0861
Serge CHarb http:// orcid. org/ 0000- 0002- 7442- 4928
REFERENCES
1 Proudfoot D, Shanahan CM. Molecular mechanisms mediating
vascular calcication: role of matrix Gla protein. Nephrology
2006;11:455–61.
2 Stafford DW. The vitamin K cycle. J Thromb Haemost
2005;3:1873–8.
3 Mizuiri S, Nishizawa Y, Yamashita K, etal. Relationship of matrix
Gla protein and vitamin K with vascular calcication in hemodialysis
patients. Ren Fail 2019;41:770–7.
4 Zwakenberg SR, Burgess S, Sluijs I, etal. Circulating phylloquinone,
inactive matrix Gla protein and coronary heart disease risk: a two-
sample Mendelian randomization study. Clin Nutr 2020;39:1131–6.
5 Cranenburg ECM, Koos R, Schurgers LJ, etal. Characterisation
and potential diagnostic value of circulating matrix Gla protein
(MGP) species. Thromb Haemost 2010;104:811–22.
6 Chen H- G, Sheng L- T, Zhang Y- B, etal. Association of vitamin K
with cardiovascular events and all- cause mortality: a systematic
review and meta- analysis. Eur J Nutr 2019;58:2191–205.
7 Luo G, Ducy P, McKee MD, etal. Spontaneous calcication of
arteries and cartilage in mice lacking matrix Gla protein. Nature
1997;386:78.
8 Murshed M, Schinke T, McKee MD, etal. Extracellular matrix
mineralization is regulated locally; different roles of two Gla-
containing proteins. J Cell Biol 2004;165:625–30.
9 Zebboudj AF, Imura M, Boström K. Matrix Gla protein, a
regulatory protein for bone morphogenetic protein- 2. J Biol Chem
2002;277:4388–94.
10 Price PA, Nguyen TMT, Williamson MK. Biochemical
characterization of the serum fetuin- mineral complex. J Biol Chem
2003;278:22153–60.
11 Sweatt A, Sane DC, Hutson SM, etal. Matrix Gla protein (MGP) and
bone morphogenetic protein- 2 in aortic calcied lesions of aging
rats. J Thromb Haemost 2003;1:178–85.
12 Fusaro M, Gallieni M, Porta C, etal. Vitamin K effects in human
health: new insights beyond bone and cardiovascular health. J
Nephrol 2020;33:239–49.
13 Luo X- H, Zhao L- L, Yuan L- Q, etal. Development of arterial
calcication in adiponectin- decient mice: adiponectin regulates
arterial calcication. J Bone Miner Res 2009;24:1461–8.
14 Huang L, Yang L, Luo L, etal. Osteocalcin improves metabolic
proles, body composition and arterial stiffening in an induced
diabetic rat model. Exp Clin Endocrinol Diabetes 2017;125:234–40.
15 Bacchetta J, Boutroy S, Guebre- Egziabher F, etal. The relationship
between adipokines, osteocalcin and bone quality in chronic kidney
disease. Nephrol Dial Transplant 2009;24:3120–5.
16 Fusaro M, Giannini S, Gallieni M, etal. Calcimimetic and vitamin D
analog use in hemodialyzed patients is associated with increased
levels of vitamin K dependent proteins. Endocrine 2016;51:333–41.
17 Confavreux CB, Szulc P, Casey R, etal. Higher serum osteocalcin
is associated with lower abdominal aortic calcication progression
and longer 10- year survival in elderly men of the Minos cohort. J
Clin Endocrinol Metab 2013;98:1084–92.
18 Son B- K, Kozaki K, Iijima K, etal. Statins protect human
aortic smooth muscle cells from inorganic phosphate- induced
calcication by restoring Gas6- Axl survival pathway. Circ Res
2006;98:1024–31.
19 Son B- K, Kozaki K, Iijima K, etal. Gas6/Axl- PI3K/Akt pathway
plays a central role in the effect of statins on inorganic phosphate-
induced calcication of vascular smooth muscle cells. Eur J
Pharmacol 2007;556:1–8.
20 Son B- K, Akishita M, Iijima K, etal. Androgen receptor- dependent
transactivation of growth arrest- specic gene 6 mediates inhibitory
effects of testosterone on vascular calcication. J Biol Chem
2010;285:7537–44.
21 Son B- K, Akishita M, Iijima K, etal. Adiponectin antagonizes
stimulatory effect of tumor necrosis factor- alpha on vascular
smooth muscle cell calcication: regulation of growth arrest-
specic gene 6- mediated survival pathway by adenosine
5'-monophosphate- activated protein kinase. Endocrinology
2008;149:1646–53.
22 Hasanbasic I, Rajotte I, Blostein M. The role of gamma-
carboxylation in the anti- apoptotic function of Gas6. J Thromb
Haemost 2005;3:2790–7.
23 Braam LA, Dissel P, Gijsbers BL, etal. Assay for human matrix Gla
protein in serum: potential applications in the cardiovascular eld.
Arterioscler Thromb Vasc Biol 2000;20:1257–61.
24 Schurgers LJ, Teunissen KJF, Knapen MHJ, etal. Novel
conformation- specic antibodies against matrix gamma-
carboxyglutamic acid (Gla) protein: undercarboxylated matrix Gla
protein as marker for vascular calcication. Arterioscler Thromb
Vasc Biol 2005;25:1629–33.
25 Hermans MMH, Vermeer C, Kooman JP, etal. Undercarboxylated
matrix Gla protein levels are decreased in dialysis patients and
related to parameters of calcium- phosphate metabolism and aortic
augmentation index. Blood Purif 2007;25:395–401.
26 Pivin E, Ponte B, Pruijm M, etal. Inactive matrix gla- protein is
associated with arterial stiffness in an adult population- based
study. Hypertension 2015;66:85–92.
27 Mansour AG, Hariri E, Daaboul Y, etal. Vitamin K2 supplementation
and arterial stiffness among renal transplant recipients- a single-
arm, single- center clinical trial. J Am Soc Hypertens 2017;11:589-
597.
28 Wei F- F, Thijs L, Cauwenberghs N, etal. Central hemodynamics
in relation to circulating Desphospho- Uncarboxylated matrix Gla
protein: a population study. J Am Heart Assoc 2019;8:e011960.
29 Mansour AG, Ahdab R, Daaboul Y, etal. Vitamin K2 status and
arterial stiffness among untreated migraine patients: a case- control
study. Headache 2020;60:589–99.
30 Ikari Y, Saito F, Kiyooka T, etal. Switching from warfarin to
rivaroxaban induces sufciency of vitamin K and reduction of
arterial stiffness in patients with atrial brillation. Heart Vessels
2020.
31 Cocciolone AJ, Hawes JZ, Staiculescu MC, etal. Elastin, arterial
mechanics, and cardiovascular disease. Am J Physiol Heart Circ
Physiol 2018;315:H189–205.
32 Meier M, Weng LP, Alexandrakis E, etal. Tracheobronchial stenosis
in Keutel syndrome. Eur Respir J 2001;17:566–9.
33 Price PA, Faus SA, Williamson MK. Warfarin causes rapid
calcication of the elastic lamellae in rat arteries and heart valves.
Arterioscler Thromb Vasc Biol 1998;18:1400–7.
34 Lerner RG, Aronow WS, Sekhri A, etal. Warfarin use and the risk of
valvular calcication. J Thromb Haemost 2009;7:2023–7.
35 Herrmann SM, Whatling C, Brand E, etal. Polymorphisms of the
human matrix Gla protein (MGP) gene, vascular calcication,
and myocardial infarction. Arterioscler Thromb Vasc Biol
2000;20:2386–93.
36 Karsli- Ceppioglu S, Yazar S, Keskin Y, etal. Association of Genetic
Polymorphisms in the Matrix Gla Protein (MGP) Gene with Coronary
Artery Disease and Serum MGP Levels. Balkan J Med Genet
2019;22:43–50.
on November 16, 2021 by guest. Protected by copyright.http://openheart.bmj.com/Open Heart: first published as 10.1136/openhrt-2021-001715 on 16 November 2021. Downloaded from
13
Hariri E, etal. Open Heart 2021;8:e001715. doi:10.1136/openhrt-2021-001715
Cardiac risk factors and prevention
37 Dalmeijer GW, van der Schouw YT, Vermeer C, etal. Circulating
matrix Gla protein is associated with coronary artery calcication
and vitamin K status in healthy women. J Nutr Biochem
2013;24:624–8.
38 Liabeuf S, Bourron O, Olivier B, Vemeer C, etal. Vascular
calcication in patients with type 2 diabetes: the involvement of
matrix Gla protein. Cardiovasc Diabetol 2014;13:85.
39 Zwakenberg SR, van der Schouw YT, Vermeer C, etal. Matrix Gla
protein, plaque stability, and cardiovascular events in patients with
severe atherosclerotic disease. Cardiology 2018;141:32–6.
40 Yamamoto K, Yamamoto H, Takeuchi M, etal. Risk factors for
progression of degenerative aortic valve disease in the Japanese-
the Japanese aortic stenosis study (JASS) prospective analysis.
Circ J 2015;79:CJ- 15- 0499.
41 Di Lullo L, Tripepi G, Ronco C, etal. Cardiac valve calcication
and use of anticoagulants: preliminary observation of a potentially
modiable risk factor. Int J Cardiol 2019;278:243–9.
42 Allison MA, Cheung P, Criqui MH, etal. Mitral and aortic annular
calcication are highly associated with systemic calcied
atherosclerosis. Circulation 2006;113:861–6.
43 Parker BD, Schurgers LJ, Vermeer C, etal. The association of
uncarboxylated matrix Gla protein with mitral annular calcication
differs by diabetes status: the heart and soul study. Atherosclerosis
2010;210:320–5.
44 Tuñón- Le Poultel D, Cannata- Andía JB, Román- García P, etal.
Association of matrix Gla protein gene functional polymorphisms
with loss of bone mineral density and progression of aortic
calcication. Osteoporos Int 2014;25:1237–46.
45 Borrás T, Smith MH, Buie LK. A novel Mgp- Cre knock- in mouse
reveals an anticalcication/antistiffness candidate gene in the
trabecular meshwork and peripapillary scleral region. Invest
Ophthalmol Vis Sci 2015;56:2203–14.
46 Fraser JD, Price PA, Lung PP. Lung, heart, and kidney express high
levels of mRNA for the vitamin K- dependent matrix Gla protein.
Implications for the possible functions of matrix Gla protein and
for the tissue distribution of the gamma- carboxylase. J Biol Chem
1988;263:11033–6.
47 Wei F- F, Trenson S, Monney P, etal. Epidemiological and
histological ndings implicate matrix Gla protein in diastolic left
ventricular dysfunction. PLoS One 2018;13:e0193967.
48 Wei F- F, Huang Q- F, Zhang Z- Y, etal. Inactive matrix Gla protein is
a novel circulating biomarker predicting retinal arteriolar narrowing
in humans. Sci Rep 2018;8:1–8.
49 Wong TY, Klein R, Nieto FJ, etal. Retinal microvascular
abnormalities and 10- year cardiovascular mortality: a population-
based case- control study. Ophthalmology 2003;110:933–40.
50 Fusaro M, Cianciolo G, Brandi ML, etal. Vitamin K and
osteoporosis. Nutrients 2020;12:3625.
51 Knapen MHJ, Jardon KM, Vermeer C. Vitamin K- induced effects on
body fat and weight: results from a 3- year vitamin K2 intervention
study. Eur J Clin Nutr 2018;72:136–41.
52 Cranenburg ECM, Schurgers LJ, Uiterwijk HH, etal. Vitamin K
intake and status are low in hemodialysis patients. Kidney Int
2012;82:605–10.
53 Holden RM, Iliescu E, Morton AR, etal. Vitamin K status of
Canadian peritoneal dialysis patients. Perit Dial Int 2008;28:415–8.
54 Keyzer CA, Vermeer C, Joosten MM, etal. Vitamin K status and
mortality after kidney transplantation: a cohort study. Am J Kidney
Dis 2015;65:474–83.
55 Wei F- F, Trenson S, Thijs L, etal. Desphospho- uncarboxylated
matrix Gla protein is a novel circulating biomarker predicting
deterioration of renal function in the general population. Nephrol
Dial Transplant 2018;33:1122–8.
56 Wei F- F, Drummen NEA, Thijs L, etal. Vitamin- K- dependent
protection of the renal microvasculature: histopathological studies
in normal and diseased kidneys. Pulse 2016;4:85–91.
57 Wei F- F, Drummen NEA, Schutte AE, etal. Vitamin K dependent
protection of renal function in multi- ethnic population studies.
EBioMedicine 2016;4:162–9.
58 Fusaro M, Noale M, Viola V, etal. Vascular calcications, and
mortality: vitamin K Italian (VIKI) dialysis study. J Bone Miner Res
2012;27:2271–8.
59 Parker BD, Ix JH, Cranenburg ECM, etal. Association of kidney
function and uncarboxylated matrix Gla protein: data from the heart
and soul study. Nephrol Dial Transplant 2009;24:2095–101.
60 Ueland T, Dahl CP, Gullestad L, etal. Circulating levels of non-
phosphorylated undercarboxylated matrix Gla protein are
associated with disease severity in patients with chronic heart
failure. Clin Sci 2011;121:119–27.
61 Kurnatowska I, Grzelak P, Masajtis- Zagajewska A, etal. Plasma
Desphospho- Uncarboxylated matrix Gla protein as a marker of
kidney damage and cardiovascular risk in advanced stage of
chronic kidney disease. Kidney Blood Press Res 2016;41:231–9.
62 Paulus WJ, Tschöpe C. A novel paradigm for heart failure with
preserved ejection fraction: comorbidities drive myocardial
dysfunction and remodeling through coronary microvascular
endothelial inammation. J Am Coll Cardiol 2013;62:263–71.
63 Ueland T, Gullestad L, Dahl CP, etal. Undercarboxylated matrix Gla
protein is associated with indices of heart failure and mortality in
symptomatic aortic stenosis. J Intern Med 2010;268:483–92.
64 Hwang DM, Dempsey AA, Lee CY, etal. Identication of
differentially expressed genes in cardiac hypertrophy by analysis of
expressed sequence tags. Genomics 2000;66:1–14.
65 Rysä J, Leskinen H, Ilves M, etal. Distinct upregulation of
extracellular matrix genes in transition from hypertrophy to
hypertensive heart failure. Hypertension 2005;45:927–33.
66 Mustonen E, Pohjolainen V, Aro J, etal. Upregulation of cardiac
matrix Gla protein expression in response to hypertrophic stimuli.
Blood Press 2009;18:286–93.
67 Mirotsou M, Dzau VJ, Pratt RE, etal. Physiological genomics
of cardiac disease: quantitative relationships between gene
expression and left ventricular hypertrophy. Physiol Genomics
2006;27:86–94.
68 Blaxall BC, Spang R, Rockman HA, etal. Differential myocardial
gene expression in the development and rescue of murine heart
failure. Physiol Genomics 2003;15:105–14.
69 Nishimoto SK, Nishimoto M. Matrix Gla protein C- terminal region
binds to vitronectin. co- localization suggests binding occurs during
tissue development. Matrix Biol 2005;24:353–61.
70 Mayer O, Seidlerová J, Bruthans J, etal. Desphospho-
uncarboxylated matrix gla- protein is associated with mortality risk
in patients with chronic stable vascular disease. Atherosclerosis
2014;235:162–8.
71 Liu Y- P, Gu Y- M, Thijs L, etal. Inactive matrix Gla protein is causally
related to adverse health outcomes: a Mendelian randomization
study in a Flemish population. Hypertension 2015;65:463–70.
72 van den Heuvel EGHM, van Schoor NM, Lips P, etal. Circulating
uncarboxylated matrix Gla protein, a marker of vitamin K status, as
a risk factor of cardiovascular disease. Maturitas 2014;77:137–41.
73 Dalmeijer GW, van der Schouw YT, Magdeleyns EJ, etal. Matrix Gla
protein species and risk of cardiovascular events in type 2 diabetic
patients. Diabetes Care 2013;36:3766–71.
74 Seidlerová J, Vaněk J, Vaněk J, etal. The abnormal status of
uncarboxylated matrix Gla protein species represents an additional
mortality risk in heart failure patients with vascular disease. Int J
Cardiol 2016;203:916–22.
75 Mayer O, Bruthans J, Seidlerová J, etal. The coincidence of low
vitamin K status and high expression of growth differentiation
factor 15 may indicate increased mortality risk in stable coronary
heart disease patients. Nutr Metab Cardiovasc Dis 2021;31:540-
551.
76 Shea MK, Booth SL, Weiner DE, etal. Circulating vitamin K is
inversely associated with incident cardiovascular disease risk
among those treated for hypertension in the health, aging, and
body composition study (health ABC). J Nutr 2017;147:888–95.
77 Nelsestuen GL, Zytkovicz TH, Howard JB. The mode of action
of vitamin K. identication of gamma- carboxyglutamic acid as a
component of prothrombin. J Biol Chem 1974;249:6347–50.
78 Walther B, Karl JP, Booth SL, etal. Menaquinones, bacteria,
and the food supply: the relevance of dairy and fermented food
products to vitamin K requirements. Adv Nutr 2013;4:463–73.
79 Thijssen HH, Drittij- Reijnders MJ. Vitamin K status in human
tissues: tissue- specic accumulation of phylloquinone and
menaquinone- 4. Br J Nutr 1996;75:121.
80 Schurgers LJ, Spronk HMH, Soute BAM, etal. Regression of
warfarin- induced medial elastocalcinosis by high intake of vitamin
K in rats. Blood 2007;109:2823–31.
81 Westenfeld R, Krueger T, Schlieper G, etal. Effect of vitamin K2
supplementation on functional vitamin K deciency in hemodialysis
patients: a randomized trial. Am J Kidney Dis 2012;59:186–95.
82 Caluwé R, Vandecasteele S, Van Vlem B, etal. Vitamin K2
supplementation in haemodialysis patients: a randomized dose-
nding study. Nephrol Dial Transplant 2014;29:1385–90.
83 Riphagen IJ, Keyzer CA, Drummen NEA, etal. Prevalence and
effects of functional vitamin K insufciency: the PREVEND study.
Nutrients 2017;9. doi:10.3390/nu9121334. [Epub ahead of print: 08
Dec 2017].
84 Theuwissen E, Magdeleyns EJ, Braam LAJLM, etal. Vitamin K
status in healthy volunteers. Food Funct 2014;5:229–34.
85 Beulens JWJ, Bots ML, Atsma F, etal. Grobbee de and van der
Schouw YT. high dietary menaquinone intake is associated with
reduced coronary calcication. Atherosclerosis 2009;203:489–93.
on November 16, 2021 by guest. Protected by copyright.http://openheart.bmj.com/Open Heart: first published as 10.1136/openhrt-2021-001715 on 16 November 2021. Downloaded from
Open Heart
14 Hariri E, etal. Open Heart 2021;8:e001715. doi:10.1136/openhrt-2021-001715
86 Shea MK, O'Donnell CJ, Hoffmann U, etal. Vitamin K
supplementation and progression of coronary artery calcium in
older men and women. Am J Clin Nutr 2009;89:1799–807.
87 Gast GCM, de Roos NM, Sluijs I, etal. A high menaquinone intake
reduces the incidence of coronary heart disease. Nutr Metab
Cardiovasc Dis 2009;19:504–10.
88 Nagata C, Wada K, Tamura T, etal. Dietary soy and natto intake
and cardiovascular disease mortality in Japanese adults: the
Takayama study. Am J Clin Nutr 2017;105:426–31.
89 Theuwissen E, Cranenburg EC, Knapen MH, etal. Low- Dose
menaquinone- 7 supplementation improved extra- hepatic vitamin
K status, but had no effect on thrombin generation in healthy
subjects. Br J Nutr 2012;108:1652–7.
90 Knapen MHJ, Braam LAJLM, Drummen NE, etal. Menaquinone- 7
supplementation improves arterial stiffness in healthy
postmenopausal women. A double- blind randomised clinical trial.
Thromb Haemost 2015;113:1135–44.
91 Geleijnse JM, Vermeer C, Grobbee DE, etal. Dietary intake of
menaquinone is associated with a reduced risk of coronary heart
disease: the Rotterdam study. J Nutr 2004;134:3100–5.
92 Dalmeijer GW, van der Schouw YT, Magdeleyns E, etal. The effect
of menaquinone- 7 supplementation on circulating species of matrix
Gla protein. Atherosclerosis 2012;225:397–402.
93 Pucaj K, Rasmussen H, Møller M, etal. Safety and toxicological
evaluation of a synthetic vitamin K2, menaquinone- 7. Toxicol Mech
Methods 2011;21:520–32.
94 Braam LAJLM, Hoeks APG, Brouns F, etal. Benecial effects of
vitamins D and K on the elastic properties of the vessel wall in
postmenopausal women: a follow- up study. Thromb Haemost
2004;91:373–80.
95 Vermeer C, Hogne V. Effect of Menaquinone- 7 (vitamin K2) on
vascular elasticity in healthy subjects: results from a one- year
study. Vasc Dis Ther 2020;5:1–4.
96 Ikari Y, Torii S, Shioi A, etal. Impact of menaquinone- 4
supplementation on coronary artery calcication and arterial
stiffness: an open label single arm study. Nutr J 2016;15:53.
97 Della Rocca DG, Pepine CJ. Endothelium as a predictor of adverse
outcomes. Clin Cardiol 2010;33:730.
98 Bar A, Kuś K, Manterys A. Vitamin K2- MK- 7 improves nitric oxide-
dependent endothelial function in ApoE/LDLR−/− mice. Vascul
Pharmacol 2019;106581.
99 Chłopicki S, Gryglewski RJ. Angiotensin converting enzyme (ACE)
and hydroxymethylglutaryl- CoA (HMG- CoA) reductase inhibitors
in the forefront of pharmacology of endothelium. Pharmacol Rep
2005;57 Suppl:86.
100 Vos M, Esposito G, Edirisinghe JN, etal. Vitamin K2 is a
mitochondrial electron carrier that rescues PINK1 deciency.
Science 2012;336:1306–10.
101 McFarlin BK, Henning AL, Venable AS. Oral consumption of vitamin
K2 for 8 weeks associated with increased maximal cardiac output
during exercise. Altern Ther Health Med 2017;23:26–32.
102 Beulens JW, Grobbee DE, Sluijs I. Spijkerman am and van der
Schouw YT. dietary phylloquinone and menaquinones intakes and
risk of type 2 diabetes. Diabetes Care 2010;33:1699–705.
103 Choi HJ, Yu J, Choi H, etal. Vitamin K2 supplementation improves
insulin sensitivity via osteocalcin metabolism: a placebo- controlled
trial. Diabetes Care 2011;34:e147.
104 Rennenberg RJMW, van Varik BJ, Schurgers LJ, etal. Chronic
coumarin treatment is associated with increased extracoronary
arterial calcication in humans. Blood 2010;115:5121–3.
105 Weijs B, Blaauw Y, Rennenberg RJMW, etal. Patients using vitamin
K antagonists show increased levels of coronary calcication: an
observational study in low- risk atrial brillation patients. Eur Heart J
2011;32:2555–62.
106 Sønderskov PS, Lindholt JS, Hallas J, etal. Association of aortic
valve calcication and vitamin K antagonist treatment. Eur Heart J
Cardiovasc Imaging 2020;21:718–24.
107 Brandenburg VM, Reinartz S, Kaesler N, etal. Slower progress
of aortic valve calcication with vitamin K supplementation:
results from a prospective interventional proof- of- concept study.
Circulation 2017;135:2081–3.
108 De Vriese AS, Caluwé R, Pyfferoen L, etal. Multicenter randomized
controlled trial of vitamin K antagonist replacement by rivaroxaban
with or without vitamin K2 in hemodialysis patients with atrial
brillation: the Valkyrie study. J Am Soc Nephrol 2020;31:186–96.
109 Oikonomaki T, Papasotiriou M, Ntrinias T, etal. The effect of vitamin
K2 supplementation on vascular calcication in haemodialysis
patients: a 1- year follow- up randomized trial. Int Urol Nephrol
2019;51:2037–44.
110 Zwakenberg SR, de Jong PA, Bartstra JW, etal. The effect of
menaquinone- 7 supplementation on vascular calcication in
patients with diabetes: a randomized, double- blind, placebo-
controlled trial. Am J Clin Nutr 2019;110:883–90.
111 Bartstra JW, Draaisma F, Zwakenberg SR, etal. Six months vitamin
K treatment does not affect systemic arterial calcication or bone
mineral density in diabetes mellitus 2. Eur J Nutr 2020:1–9.
112 Haugsgjerd TR, Egeland GM, Nygård OK, etal. Association of
dietary vitamin K and risk of coronary heart disease in middle-
age adults: the Hordaland health study cohort. BMJ Open
2020;10:e035953.
113 Erkkilä AT, Booth SL, Hu FB, etal. Phylloquinone intake and risk
of cardiovascular diseases in men. Nutr Metab Cardiovasc Dis
2007;17:58–62.
114 Juanola- Falgarona M, Salas- Salvadó J, Martínez- González Miguel
Ángel, etal. Dietary intake of vitamin K is inversely associated with
mortality risk. J Nutr 2014;144:743–50.
115 Cheung C- L, Sahni S, Cheung BMY, etal. Vitamin K intake and
mortality in people with chronic kidney disease from NHANES III.
Clin Nutr 2015;34:235–40.
116 Vossen LM, Schurgers LJ, van Varik BJ, etal. Menaquinone- 7
supplementation to reduce vascular calcication in patients with
coronary artery disease: rationale and study protocol (VitaK- CAC
trial). Nutrients 2015;7:8905–15.
117 Lindholt JS, Frandsen NE, Fredgart MH, etal. Effects of
menaquinone- 7 supplementation in patients with aortic valve
calcication: study protocol for a randomised controlled trial. BMJ
Open 2018;8:e022019.
118 Hauschka PV, Wians FH. Osteocalcin- hydroxyapatite interaction in
the extracellular organic matrix of bone. Anat Rec 1989;224:180–8.
119 Asemi Z, Raygan F, Bahmani F, etal. The effects of vitamin D, K and
calcium co- supplementation on carotid intima- media thickness and
metabolic status in overweight type 2 diabetic patients with CHD.
Br J Nutr 2016;116:286–93.
120 Kurnatowska I, Grzelak P, Masajtis- Zagajewska A, etal. Effect
of vitamin K2 on progression of atherosclerosis and vascular
calcication in nondialyzed patients with chronic kidney disease
stages 3- 5. Pol Arch Med Wewn 2015;125:631–40.
121 Zwakenberg SR, den Braver NR, Engelen AIP, etal. Vitamin
K intake and all- cause and cause specic mortality. Clin Nutr
2017;36:1294–300.
on November 16, 2021 by guest. Protected by copyright.http://openheart.bmj.com/Open Heart: first published as 10.1136/openhrt-2021-001715 on 16 November 2021. Downloaded from
