Intervention study on the effect of vitamin K2 (Menaquinone-7) supplementation on the vascular stiffness in subjects with poor vitamin K-status.

Population-based studies have shown that low dietary vitamin K intake is
associated with increased risk of coronary calcification and cardiovascular
morbidity & mortality. The mechanism behind this marked correlation between
K-intake and CVD is probably based on the strong calcification-inhibitory
activity of the vitamin K-dependent Matrix-Gla protein (MGP). MGP is
synthesized by vascular smooth muscle cells and chondrocytes. MGP is thought to
exert its function as a calcification inhibitor by binding to crystal nuclei in
hydroxyapatite, thereby preventing crystal growth. In order to acquire its
calcification-inhibitory activity, MGP must be activated in a vitamin
K-dependent post-translational carboxylation reaction. In many prospective
studies in unrelated patient cohorts it appeared that dp-ucMGP (inactive MGP)
is the strongest risk marker for unfavorable cardiovascular outcomes. Patient
groups included aortic stenosis, heart failure, chronic kidney disease and
hemodialysis, kidney transplant recipients, diabetics, coronary artery disease
and peripheral artery disease. In a recent study among 2500 healthy adults with
a follow-up period of 15 years it turned out that poor vitamin K status (as
concluded from high circulating dp-ucMGP levels) is a strong risk marker for
cardiovascular mortality, and that the risk is especially high in the upper
quartile of circulating dp-ucMGP, i.e. above 400 pM.

Accelerated Plethysmography (APG) has been described as a non-invasive
technique to measure vascular stiffness and aging. Due to the process of
arteriosclerosis, vessel stiffness increases with age, resulting in changes in
the peripheral pulse wave. These changes can be measured using the APG
technique. Several studies show that parameters of the APG wave signals can be
used to determine characteristics of vascular aging. APG ratios have also been
found to be correlated with vessel distensibility and atherosclerotic changes
in the carotid artery, blood pressure and gender. Several other studies also
showed that APG and Pulse Wave Velocity (PWV) are correlated with each other.
In this follow-up study we compare this APG-technique with two existing
techniques (ultrasound of the carotid artery and PWV) to determine the
correlation between the 3 measurements concerning arterial stiffness.

The primary objective of this study is to investigate the effect of MK-7
supplementation on vascular stiffness in a subgroup of subjects with poor
vitamin K status.

For this follow-up study the primary objective is to investigate the
correlation between the 3 different non-invasive measurements for vascular
stiffness in healthy subjects.

This is a dubbel-blind randomized placebo-controlled intervention study among
240 healthy men and women in the age of 40 -70 year, who are preselected based
on their circulating inactive MGP concentration (>400 pM):
- group 1: n=120 men and women; daily intake of 1 tablet containing 0 microgram
of MK-7 during 1 year;
- group 2: n=120 men and women; daily intake of 1 tablet containing 180
microgram of MK-7 during 1 year.

In order to include the subject the level of circulating inactive MGP has to be
determined. At the first visit blood will be taken to measure this inactive
form of MPG (dp-ucMGP). After inclusion the participants have to come to our
trialcenter for their second visit. This visit is the start of the study,
during which the vesselwall characteristics, the pulse wave velocity and the
body composition will be measured. Also blood will be taken after an overnight
fasting period. The placebo/MK-7 tablets will be given for 6 months. Tablets
should be consumed together with breakfast or dinner. After 6 months our
investigators will visit the participants at home/work to deliver the tablets
for the next 6 months. Remaining tablets should be handed over to the
investigator. After the total intervention period of 1 year all participants
undergo the same measurements and the venapuncture. Remaining tablets have to
be brought back to the trial center to check for their compliance. Participants
haver to report all changes concerning medication, illness. For each subject a
CRF will be recorded for each subject. The participants will be asked not to
change their lifestyle, dietary habits or level of physical activity to a great
extent during the intervention period.

From this study population eligible participants (men and women) will be
selected. The study information will be send to them by mail or post (if they
don*t have a mail address). If they are interested to participate they can
contact us by mail/phone, If no reaction is given within 2 weeks we will send a
reminder. Participants willing to participate will be contacted by phone and an
appointment will be made to come to the site for the measurements if they meet
the in- and exclusion criteria.In total 100 participants will be invited.
Measurements will be performed at the same day (vessel wall characteristics of
the common carotid artery, PWV and the measurement of the heart rate, oxygen
saturation, stiffness score with the oxymeter).

The total group of 240 men and women will be randomly assigned to 2 groups:
- n=120 men and women: daily intake of 1 tablet with 0 microgram of MK-7 during
1 year
- n=120 men and women: daily intake of 1 tablet with 180 microgram of MK-7
during 1 year.

In total, participants will undergo 3 venipunctures in a period of 1 year. The
venipunctures will be made by experienced coworkers. For the first venipuncture
a fasting condition is not necessary. A fasting period of at least 10 h is
necessary for the venipunctures during the study visits at baseline and after 1
year. The daily dosage of vitamin K2 (180 µg) for the intervention period of 1
year will not cause adverse side-effects. Previous studies on vitamin K
intervention used dosages between 180 µg and 45 mg of vitamin K. No adverse
side-effects were reported by these intervention studies. Another burden is the
low dose of X-ray radiation participants receive during the WB-scan (Category
1: <0.1 mSv). No adverse effects are to be expected from the ultrasound
technique. A personal benefit that participants may obtain from the study is
that detailed information is obtained on vascular health and their body
composition at baseline, and the changes after one year. Subjects with
extensive carotid artery calcifications will be referred to their GP, but if no
treatment is installed, they are eligible to participate in the study.The use
of the fingertip oxymeter will not cause any adverse effects. In conclusion,
the risks for the participants of this study are minimal.