Vitamin K2 dosage and evidence
Written by Aaron CuhaReviewed Sep 2026
The short answer
Vitamin K2 is the K2 half of Aaron's vitamin D3 plus K2 pairing. In the Rotterdam Study, people who ate more K2 in their food had less heart disease. In a three-year trial, healthy women past menopause who took K2 (as MK-7) lost less bone. If you take the blood thinner warfarin, K2 is off the table.
Evidence grade for Vitamin K2: Preliminary. The rule: studied in people, but no published study has had people take it. The sum on this page: 2 human studies where nobody was given it. A grade counts how much has been done to people, not whether it works.
- People given it
- 0
- Human studies
- 0
- Found nothing
- 0
Dose
No human dose established
No published study on this page has given this compound to people and reported a result.
2 human studies where nobody was given it
1 effects reported, 1 unwanted, by people using it, not a trial
Goal pages: Bone and joints
In plain English
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
Vitamin K2 is a group of vitamins you get from food. The kind most pills sell is called MK-7. It helps switch on proteins that build bone and help blood clot. I take it next to vitamin D3. That pairing is my choice, not something a trial proved.
What people take it for
- Stronger bones, especially after menopause.
- Keeping calcium out of the arteries and protecting the heart.
- Pairing it with vitamin D3, because the two are sold together.
What studies in people showed
In the Rotterdam Study, people who ate more K2 in their food had less heart disease. That was a food survey, not a pill trial. In a three-year trial, healthy women past menopause took a low dose of MK-7. They lost less bone than the other group. That is bone density, not fewer broken bones. No trial has tested D3 plus K2 against D3 alone for deaths or heart attacks.
What people report
Reports, not study results
The good
- We have not collected user reports on this one yet.
The bad
- The warning on this page: K2 can interfere with warfarin and similar blood thinners. If you take one, do not add K2 on your own.
Where these come from: We have no forum or clinic reports for this one. The warning comes from the medicine notes on this page.
My bottom line
I take K2 with my D3, and I will tell you straight that it is a choice, not a proven must. The bone trial is decent. If you are on warfarin, leave it alone and ask your doctor.
An opinion, not a finding. I am a coach, not a doctor.
What it has been measured to do
Measured in people
Goals Vitamin K2 has been tested for in people, biggest studies first. We count only what the studies on this page say, so the real numbers may be higher.
- Bone strengthno headcount stated · 1 study
35 of the 36 indexed goals have no study of any kind behind Vitamin K2
No study in people, animals or cells on this page reports a result for these. That does not prove Vitamin K2 does nothing for them. It does mean anything you have heard about Vitamin K2 and one of these did not come from a study cited here.
When this earns a spot
It sits on the owner's basic list next to D3, as MK-7. It is not a stand-alone longevity drug. A three-year study that gave MK-7 to healthy women past menopause reported less bone loss. In the Rotterdam study, which only watched people, eating more K2 went with less heart disease. If you take warfarin or any other blood thinner that works against vitamin K, you must check with a doctor. Do not start K2 on those medicines because of a web page.
Aaron's list, tier 1
Bloodwork that belongs beside the bottle
Think about K2 next to your 25-OH D result and your medicine list, not as its own stack.
Test again after about 90 days. If that blood number did not move, stop.
- There is no routine K2 blood test this site will tell you to chase.
- If you are on a blood thinner, your doctor handles your INR clotting test, and K2 is not your call.
Reading the number
If you are on warfarin, this bottle is not yours to add. If you are not, K2 is an optional add-on to D3. Calcium in the heart arteries is something a doctor checks with a scan, not something a K2 plan handles.
What these tests mean: 25-hydroxy vitamin D.
What people typically order
Ask the doctor who manages your vitamin D whether K2 is safe with your medicines. Do not order a home clotting test kit to justify a capsule.
Show full evidence
What is Vitamin K2?
Vitamin K2 is the K2 half of Aaron's vitamin D3 plus K2 pairing. In the Rotterdam Study, people who ate more K2 in their food had less heart disease. In a three-year trial, healthy women past menopause who took K2 (as MK-7) lost less bone. If you take the blood thinner warfarin, K2 is off the table.
Vitamin K2 is a family of related vitamins called menaquinones. The one most often sold is MK-7. Aaron takes it with vitamin D3. That pairing is his choice. No trial has split people into D3 plus K2 versus D3 alone and counted deaths or broken bones in a general longevity crowd.
In the Rotterdam Study, people who ate more K2 in their food had less heart disease. That comes from surveys of what people ate, not from a capsule trial. In a three-year trial, healthy women past menopause were given low-dose MK-7, and they lost less bone than the comparison group. It is one of the cleaner human studies this page can honestly point to.
The hard limit is blood thinners. Anyone on warfarin, or another drug that works against vitamin K, does not add K2 because a webpage said so. There is no home K2 blood test this site will tell you to chase. Read it beside your vitamin D level (25-OH D) and your medicine list.
How does Vitamin K2 work?
Vitamin K helps switch on certain proteins, including clotting factors and osteocalcin, a bone protein. MK-7 is a long form of K2 that stays in the blood longer than MK-4. Switching on osteocalcin and another protein, matrix Gla protein, is the basis of the claims about bone and about keeping calcium out of arteries. How something works is not proof that it helps.
What have studies in people found about Vitamin K2?
One useful bone-density trial for MK-7, plus a large food survey linking K2 to less heart disease. No trial on this page tested a D3 plus K2 capsule for deaths or heart attacks.
- Rotterdam: people who ate more K2 in food, not K2 from a capsule, had less heart disease.
- A three-year MK-7 trial in healthy women past menopause found they lost less bone.
- Nobody on this page was assigned by chance to D3 plus K2 versus D3 alone and followed for deaths.
What this does not tell you: This is not a green light to start K2 on warfarin. What people eat is not the same as a capsule. Bone density is not the same as broken bones. A later update should cover the artery-calcium scan research properly, or say it cannot.
The evidence, in charts
Fig. 1a · how many people
2studies in people cited, but none says how many people took part
number of people not stated
We do not draw a total, because none of the studies in people on this page gives one. Read the sources below for what each study measured.
We read the number of people from the source lines on this page. Where a line gives no number, we count nothing for it. We do not guess.
Fig. 1b · evidence mix
All 2 sources here are studies in people.
- Study in people · done in people2100%
Counted from the list of sources on this page. It counts only what we cite, so there may be more studies out there. A review counts once, however many studies it sums up.
Fig. 2 · evidence over time
Sources here come from just two years, 2004 and 2013.
Too few different years on this page to draw a timeline. The newest source on file is from 2013, more than five years ago. Research on it may have gone quiet.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four countries shown. This is what the law says, not a verdict on the science. See Legal status below for the full text and any notes.
Fig. 4 · how much does what
Nobody has tested different amounts in people
This chart would show how the effect changes as the amount goes up. For this compound, nobody has measured that in people. So we leave it empty. We will not borrow an animal chart and pretend it works the same in people.
Fig. 5 · what the molecule is
- Kind of compound
- Supplement
- Molecule weight
- MK-7 about 649 Da. A fat-soluble vitamin, not a peptide.
- Half-life
- None on file
- Chain length
- None on file
No amino acid sequence is on file for Vitamin K2, which is expected: a supplement is not built from amino acids.
The studies we cite
- Study in people2004Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study.
People who ate more K2 in their food had less heart disease and less calcium in the main artery. This was a survey of what people ate, not a capsule trial. Vitamin K1 did not show the same link.
Observational. Higher dietary menaquinone associated with less coronary heart disease and aortic calcification. Not a capsule trial and not phylloquinone (K1) showing the same pattern.
- Study in people2013Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women.
Healthy women past menopause who took a low dose of K2 for three years lost less bone. That is bone density, not broken bones, and it was not a test of living longer.
Randomised MK-7 for three years in healthy postmenopausal women. Reported attenuated bone loss. Not a fracture-outcome trial and not a general-population longevity trial.
Common questions
Has Vitamin K2 been tested in people?
Not in a completed trial cited here. 2 human studies where nobody was given it. Vitamin K2 is the K2 half of Aaron's vitamin D3 plus K2 pairing. In the Rotterdam Study, people who ate more K2 in their food had less heart disease. In a three-year trial, healthy women past menopause who took K2 (as MK-7) lost less bone. If you take the blood thinner warfarin, K2 is off the table.
What is the Vitamin K2 dosage?
No human dose established. No published study on this page has given this compound to people and reported a result. 2 human studies where nobody was given it
Is Vitamin K2 FDA-approved?
Sold as a dietary supplement in the United States. Not approved to prevent heart disease or broken bones. Warfarin is still a prescription blood thinner, and K2 can throw it off.
Do I take K2 because I take vitamin D?
Aaron does. That is his pairing, not something a trial says you must do. The reason to stop and think is a medicine that depends on vitamin K, like warfarin, not a missing blood test.
Is this a blood-marker supplement?
Not on its own. Check your vitamin D level (25-OH D). There is no routine home K2 test this site treats as a reason to start or stop.
Latest reading on Vitamin K2
Blog posts about Vitamin K2, newest first.