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?

1. Natto
2. Hard cheese
3. Soft cheese
4. Egg yolks
5. Butter
6. Chicken liver
7. Ground beef
8. Salami
9. Bacon
10. 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.