Vitamin K2 is a fat-soluble vitamin found in fermented foods, eggs, and certain animal products. It belongs to the same vitamin K family as K1 (found in leafy greens), but it has a very different job — while K1 mainly helps blood clot, K2 acts as a traffic director for calcium in the body.

How does Vitamin K2 work?

K2 activates two key proteins: osteocalcin, which anchors calcium into bone tissue, and Matrix Gla Protein (MGP), which prevents calcium from depositing in artery walls. Without enough K2, these proteins stay inactive, and calcium can build up in the wrong places — weakening bones while stiffening blood vessels.

How much Vitamin K2 should you take?

90–200 mcg MK-7 for general bone and cardiovascular health. Japanese clinical trials for osteoporosis have used 45 mg (45,000 mcg) MK-4 daily — this high dose should only be used under medical supervision. Most adults benefit from 100–200 mcg MK-7 daily.

How long does Vitamin K2 take to work?

Measurable changes in bone density or arterial stiffness typically require 6–12 months of consistent use. Activation of K2-dependent proteins begins much sooner, but structural changes take time.

What are the side effects of Vitamin K2?

Reported side effects of Vitamin K2 include warfarin interaction, mild digestive upset at very high doses in rare cases and no known toxicity at standard doses of 90.

What forms does Vitamin K2 come in?

MK-7 at 90–200 mcg per day is the most studied and practical supplemental form for general use. Combined D3+K2 supplements are popular because Vitamin D increases calcium absorption, making K2's routing function even more important.

Which foods are rich in Vitamin K2?

Foods rich in Vitamin K2 include natto (fermented soybeans), hard cheeses (Gouda, Edam), egg yolks (pasture-raised), chicken liver and organ meats and butter and ghee (grass-fed).

Vitamin K2

Traditionally used for: Bone health; Heart and artery health; Calcium management. Supports bone density, protects arteries from calcification.

Home

What is it? Vitamin K2, also known as menaquinone, is a fat-soluble vitamin that plays a vital role in blood clotting, bone health, and cardiovascular health. How does it work for medicinal purposes? Vitamin K2 acts as a cofactor for the enzyme responsible for activating specific proteins in the body. These proteins help regulate blood clotting, bone metabolism, and cardiovascular health. What are the active ingredients that are important for its medicinal properties? The active ingredient in vitamin K2 is menaquinone. What forms does it come in? Vitamin K2 can be found in food sources such as fermented soybeans, cheese, and meat. It is also available as a dietary supplement in various forms such as capsules and tablets. What if I have an imbalance or deficiency? A vitamin K2 deficiency can lead to an increased risk of bone fractures, cardiovascular disease, and excessive bleeding. An imbalance can result in a reduction in the effectiveness of blood-thinning medications. When was it first used for medicinal purposes? Vitamin K was discovered in 1929 and later identified as an essential nutrient for blood clotting. The role of vitamin K2 in bone and cardiovascular health was later discovered.

Helps

What does Vitamin K2 help with? Vitamin K2 is a fat-soluble vitamin found in food. People get it from fermented foods such as Japanese natto, and from cheese, egg yolk and liver. Supplements come in two main forms, called MK-4 and MK-7. Bone loss in the years after menopause Good evidence — MK-7 supplement trials in postmenopausal women, with placebo groups. Bone loss speeds up after menopause because of hormone changes. In these trials, women taking MK-7 held on to more bone mineral density than women on placebo. The trials measured bone scans, not broken bones. Evidence grade B · Traditional tier T0 Thinning, fragile bones (osteoporosis) Good evidence — clinical trials, mainly MK-4 at higher doses in Japan. Trials gave women with osteoporosis higher-dose MK-4, mostly in Japan. Fracture rates fell in those trials. The file holds this work mainly from one country, so it may not carry over everywhere. Evidence grade B · Traditional tier T0 Stiff arteries Good evidence — MK-7 supplement trials that measured artery stiffness over time. Stiff arteries are a risk factor for high blood pressure and heart events. In supplement trials, people taking MK-7 had less artery stiffness as time went on. Researchers think this works through a protein called MGP, but that step is a theory, not a finding. Evidence grade B · Traditional tier T0 Calcium building up in artery walls Early evidence — population studies plus a small number of supplement trials. In population studies, people with low K2 status had more artery calcium and higher heart risk. Those studies show a link, not a cause. In lab research, K2 switches on Matrix Gla Protein, which holds calcium back from vessel walls. Evidence grade C · Traditional tier T0 Low bone density that is not yet osteoporosis (osteopenia) Early evidence — carried over from bone trials in older and postmenopausal women; no separate osteopenia trial on file. The bone trials on file were run in women with osteoporosis or past menopause. The library holds no separate trial in people with osteopenia alone. K2 is studied alongside vitamin D and calcium, not on its own. Evidence grade C · Traditional tier T0 Making sure high-dose vitamin D sends calcium to bone Not yet tested in people — reasoning from how the vitamins work; no human trial on file. Vitamin D is well established to raise how much calcium you absorb from food. Where that extra calcium ends up is the open question. Some researchers worry that lots of vitamin D with little K2 adds to soft-tissue calcium, but no trial on file has tested this. Evidence grade insufficient · Traditional tier T0 Tooth decay and stronger teeth Not yet tested in people — early laboratory work on dentin; no human trial on file. In lab work, K2 switches on osteocalcin in dentin, the hard layer under enamel. Some early research has looked at whether this matters for rebuilding tooth mineral. This area is far less studied than bone and arteries. Evidence grade insufficient · Traditional tier T0 Kidney stones Not yet tested in people — a proposed mechanism only; direct trial evidence still developing. High calcium in the urine is one cause of some kidney stones. The idea on file is that good K2 status routes calcium to bone instead. No human trial on file has tested that idea. Evidence grade insufficient · Traditional tier T0 What Vitamin K2 has not been shown to do No trial on file shows that K2 prevents heart attacks or strokes; the heart trials measured artery stiffness instead. K2 has not been shown to clear calcium already lodged in artery walls; that is a proposed explanation, not a result. No trial on file shows that K2 lowers blood pressure. No trial on file shows that K2 prevents or dissolves kidney stones. No trial on file shows that K2 stops or reverses tooth decay. K2 has not been shown to stand in for vitamin D or calcium; the bone work pairs it with both. The drop in fractures comes from Japanese MK-4 trials; the MK-7 trials on file tracked bone scans, not broken

Vitamin K2

Q: What does Vitamin K2 help with?

Vitamin K2 is traditionally used for bone loss and osteoporosis, artery calcification and heart health, low bone density (osteopenia), dental health and tooth decay, postmenopausal bone loss, vitamin D and calcium imbalance, arterial stiffness and kidney stone risk.

Quick Facts

What it is: A fat-soluble vitamin that tells your body where calcium belongs — in bones and teeth, not in your arteries.
Main uses: Supports bone density, protects arteries from calcification, and works with Vitamin D to manage calcium in the body.
Best for: Bone health, Heart and artery health, Calcium management
Active ingredients: Menaquinone-7 (MK-7), Menaquinone-4 (MK-4)
Forms: Softgel capsule, Oil-based capsule, Liquid drops, Tablet, Combined D3+K2 formula
Time to effect: Bone and cardiovascular benefits typically emerge over 6–12 months of consistent use.
Side effects: Very well tolerated at normal doses; may interact with blood-thinning medications like warfarin.
Pregnancy & breastfeeding: Not assessed for this entry. Ask your doctor or midwife before use.

Educational information, not medical advice — ask your doctor or midwife.

What is it?

Vitamin K2, also known as menaquinone, is a fat-soluble vitamin that plays a vital role in blood clotting, bone health, and cardiovascular health.

How does it work for medicinal purposes?

Vitamin K2 acts as a cofactor for the enzyme responsible for activating specific proteins in the body. These proteins help regulate blood clotting, bone metabolism, and cardiovascular health.

What are the active ingredients that are important for its medicinal properties?

The active ingredient in vitamin K2 is menaquinone.

What forms does it come in?

Vitamin K2 can be found in food sources such as fermented soybeans, cheese, and meat. It is also available as a dietary supplement in various forms such as capsules and tablets.

What if I have an imbalance or deficiency?

A vitamin K2 deficiency can lead to an increased risk of bone fractures, cardiovascular disease, and excessive bleeding. An imbalance can result in a reduction in the effectiveness of blood-thinning medications.

When was it first used for medicinal purposes?

Vitamin K was discovered in 1929 and later identified as an essential nutrient for blood clotting. The role of vitamin K2 in bone and cardiovascular health was later discovered.

What does Vitamin K2 help with?

Vitamin K2 is a fat-soluble vitamin found in food. People get it from fermented foods such as Japanese natto, and from cheese, egg yolk and liver. Supplements come in two main forms, called MK-4 and MK-7.

Bone loss in the years after menopause
Good evidence — MK-7 supplement trials in postmenopausal women, with placebo groups. Bone loss speeds up after menopause because of hormone changes. In these trials, women taking MK-7 held on to more bone mineral density than women on placebo. The trials measured bone scans, not broken bones.
Evidence grade B · Traditional tier T0
Thinning, fragile bones (osteoporosis)
Good evidence — clinical trials, mainly MK-4 at higher doses in Japan. Trials gave women with osteoporosis higher-dose MK-4, mostly in Japan. Fracture rates fell in those trials. The file holds this work mainly from one country, so it may not carry over everywhere.
Evidence grade B · Traditional tier T0
Stiff arteries
Good evidence — MK-7 supplement trials that measured artery stiffness over time. Stiff arteries are a risk factor for high blood pressure and heart events. In supplement trials, people taking MK-7 had less artery stiffness as time went on. Researchers think this works through a protein called MGP, but that step is a theory, not a finding.
Evidence grade B · Traditional tier T0
Calcium building up in artery walls
Early evidence — population studies plus a small number of supplement trials. In population studies, people with low K2 status had more artery calcium and higher heart risk. Those studies show a link, not a cause. In lab research, K2 switches on Matrix Gla Protein, which holds calcium back from vessel walls.
Evidence grade C · Traditional tier T0
Low bone density that is not yet osteoporosis (osteopenia)
Early evidence — carried over from bone trials in older and postmenopausal women; no separate osteopenia trial on file. The bone trials on file were run in women with osteoporosis or past menopause. The library holds no separate trial in people with osteopenia alone. K2 is studied alongside vitamin D and calcium, not on its own.
Evidence grade C · Traditional tier T0
Making sure high-dose vitamin D sends calcium to bone
Not yet tested in people — reasoning from how the vitamins work; no human trial on file. Vitamin D is well established to raise how much calcium you absorb from food. Where that extra calcium ends up is the open question. Some researchers worry that lots of vitamin D with little K2 adds to soft-tissue calcium, but no trial on file has tested this.
Evidence grade insufficient · Traditional tier T0
Tooth decay and stronger teeth
Not yet tested in people — early laboratory work on dentin; no human trial on file. In lab work, K2 switches on osteocalcin in dentin, the hard layer under enamel. Some early research has looked at whether this matters for rebuilding tooth mineral. This area is far less studied than bone and arteries.
Evidence grade insufficient · Traditional tier T0
Kidney stones
Not yet tested in people — a proposed mechanism only; direct trial evidence still developing. High calcium in the urine is one cause of some kidney stones. The idea on file is that good K2 status routes calcium to bone instead. No human trial on file has tested that idea.
Evidence grade insufficient · Traditional tier T0

What Vitamin K2 has not been shown to do

No trial on file shows that K2 prevents heart attacks or strokes; the heart trials measured artery stiffness instead.
K2 has not been shown to clear calcium already lodged in artery walls; that is a proposed explanation, not a result.
No trial on file shows that K2 lowers blood pressure.
No trial on file shows that K2 prevents or dissolves kidney stones.
No trial on file shows that K2 stops or reverses tooth decay.
K2 has not been shown to stand in for vitamin D or calcium; the bone work pairs it with both.
The drop in fractures comes from Japanese MK-4 trials; the MK-7 trials on file tracked bone scans, not broken bones.

How to read this:

Each grade above rates the evidence for that one use, not for vitamin K2 as a whole. A means steady results across randomised human trials. B means at least one good human trial. C means small or mixed human work. D means weak or clashing human results. Insufficient means no human trial is on file. This page reports what studies found. It is not medical advice, and it is not a claim that K2 treats any condition. Talk with your own clinician, above all if you take a blood thinner.

What can Vitamin K2 help prevent?

Arterial calcification with long-term adequate intake
Osteoporotic fractures: particularly in postmenopausal women with MK-4 supplementation
Progression of coronary artery calcification in at-risk adults

Which foods are rich in it?

Natto
Hard cheese
Soft cheese
Egg yolks
Butter
Chicken liver
Ground beef
Salami
Bacon
Beef liver

What are possible side effects?

Vitamin K2 is generally well-tolerated. The most common side effects include gastrointestinal discomfort, nausea, and allergic reactions.

What's the recommended daily dose?

The recommended daily intake for vitamin K2 is 90-120 micrograms for adult men and women.

How many days does it take to work?

The length of time it takes for vitamin K2 to work varies depending on the condition being treated. Improvement in bone density may take up to six months, while improvements in cardiovascular health may be seen in as little as four weeks.

What time of day is best to take it?

There is no specific time of day recommended for taking vitamin K2.

Is it best to take it with or without food?

Vitamin K2 can be taken with or without food.

Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.

Vitamin K2

Home

Helps

Vitamin K2

Quick Facts

What is it?

How does it work for medicinal purposes?

What are the active ingredients that are important for its medicinal properties?

What forms does it come in?

What if I have an imbalance or deficiency?

When was it first used for medicinal purposes?

What does Vitamin K2 help with?

What Vitamin K2 has not been shown to do

How to read this:

What can Vitamin K2 help prevent?

Which foods are rich in it?

What are possible side effects?

What's the recommended daily dose?

How many days does it take to work?

What time of day is best to take it?

Is it best to take it with or without food?

Remedies related to Vitamin K2

People take Vitamin K2 when they say

Conditions where Vitamin K2 is recommended

Natural options for Muscle Cramps, ranked by evidence