Plain English Summary
Background and study aims
Low intake of vitamin K in the diet has been linked to a higher risk of heart attacks and strokes. This may be because vitamin K is important in keeping blood vessels in good health; low levels of vitamin K are associated with stiffer blood vessels and deposits of calcium in the blood vessel wall. Vitamin K may also be important in keeping nerves working well which are important in maintaining balance and avoiding falls. It is not known whether taking extra vitamin K (as a tablet) can improve balance or blood vessel health, so the aim of this study is to test whether taking a vitamin K tablet for 6 months improves blood vessel health and improves balance in older people who have had (or are at risk of) a heart attack or stroke.
Who can participate?
Older people aged 70 and over who have had (or are at risk of) a heart attack or stroke
What does the study involve?
Participants are randomly allocated to take either vitamin K or a matching placebo (dummy) tablet once a day for 6 months. They are then followed up to assess their blood vessel health and balance.
What are the possible benefits and risks of participating?
If vitamin K improves blood vessel health, it might reduce the risk of heart attacks and strokes, but this study is too small to show this directly. Vitamin K is safe with no known side effects. It can interfere with the action of the drug warfarin, which is why patients on warfarin are excluded from the study.
Where is the study run from?
Ninewells Hospital (UK)
When is the study starting and how long is it expected to run for?
August 2011 to March 2013
Who is funding the study?
Chest Heart and Stroke Scotland (UK)
Who is the main contact?
Dr Miles Witham
Vitamin K to improve markers of vascular health and physical function in older people with vascular disease: a randomised controlled trial
To test whether vitamin K supplementation improves markers of vascular health in older people with vascular disease.
East of Scotland NHS Research Ethics Committee, 12/09/2011, ref: 11/ES/0009
Parallel-group double-blind placebo-controlled randomised trial
Primary study design
Secondary study design
Randomised parallel trial
Patient information sheet
Not available in web format, please use the contact details to request a patient information sheet
Vitamin K2 (MK7 subtype) 100 mcg per day or placebo.
Participants are randomised to take either:
1. Vitamin K2 (MK7 subtype) given as 100 mcg oral tablet once a day for 6 months
2. Matching placebo tablet, given once a day for 6 months
Treatment in both arms given for 6 months, which is also the length of follow up.
Primary outcome measure
Flow-mediated dilatation of the brachial artery measured at baseline and 6 months
Secondary outcome measures
Measured at baseline, 3 months and 6 months:
1. Markers of vascular function:
1.1. Arterial stiffness and reflectivity, measured using pulse wave velocity and augmentation index
1.2. Carotid intima-media thickness and compliance
2. Markers of vascular prognosis: brain natriuretic peptide (BNP), office blood pressure (BP) (lying and standing), total cholesterol, high density lipoprotein (HDL) cholesterol, low density lipoprotein (LDL) cholesterol
3. Markers of inflammation: high-sensitivity C-reactive protein
4. Serum MK7 levels, measured by high-performance liquid chromatography (HPLC)
5. Markers of physical function:
5.1. Short Physical Performance Battery; predicts disability, falls and death
5.2. Balance, measured using force plate analysis
5.3. Grip strength as a test of maximal muscle strength; predicts institutionalisation and death
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. Aged 70 and over
2. At least one of the conditions:
2.1. Hypertension (based on recorded diagnosis from primary or secondary care)
2.2. Diabetes mellitus (based on recorded diagnosis from primary or secondary care)
3. Established vascular disease: myocardial infarction [based on symptoms of ischaemia or electrocardiogram (ECG) changes, plus rise in cardiac enzymes]
4. Percutaneous transluminal coronary angioplasty
5. Coronary artery bypass grafting
6. Stroke/transient ischaemic attack (TIA) (diagnosis established in secondary care)
7. Peripheral vascular disease (symptoms of peripheral ischaemia and either a previous ankle/brachial pressure index < 0.7 or previous evidence of arterial stenosis on angiography or ultrasound)
Target number of participants
Participant exclusion criteria
1. Atrial fibrillation
2. Taking warfarin
3. Unable to give written informed consent
4. Unable to walk without human assistance (walking aids are permitted)
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Chest Heart and Stroke Scotland (ref: R11/A137)
Funding Body Type
private sector organisation
Funding Body Subtype
professional associations and societies
Results and Publications
Publication and dissemination plan
Manuscript accepted for publication.
IPD sharing statement
The datasets generated during and/or analysed during the current study are available upon request from Dr Miles Witham (email@example.com). Anonymised individual participant data on all those randomised will be made available to bona fide researchers for non-commercial use, subject to sight of an analysis plan and subject to appropriate data sharing agreements and approval from the trial Sponsor.
Intention to publish date
Participant level data
Available on request
Basic results (scientific)
See additional file ISRCTN93213492_BasicResults_04Aug2017.pdf
2016 results in: https://www.ncbi.nlm.nih.gov/pubmed/26892582
- ISRCTN93213492_BasicResults_04Aug2017.pdf Uploaded 22/08/2017