Vitamin K2: Everything You Need to Know

Most people have never heard of vitamin K2. This vitamin is rare in the Western diet and hasn’t received much mainstream attention.

However, this powerful nutrient plays an essential role in many aspects of your health. In fact, some think that vitamin K2 may be the missing link between diet and several chronic diseases.

 

 

Vitamin K was discovered in 1929 as an essential nutrient for blood coagulation, which is the scientific term for blood clotting.

The initial discovery was reported in a German scientific journal, where it was called “Koagulationsvitamin.” That’s where the K in vitamin K comes from (1).

It was also discovered by the dentist Weston Price, who traveled the world in the early 20th century, studying the relationship between diet and disease in different populations.

He found that the nonindustrial diets were high in an unidentified nutrient, which seemed to provide protection against tooth decay and chronic disease.

He referred to this mystery nutrient as activator X. It’s now believed to have been vitamin K2 (1).

There are two main forms of vitamin K:

• Vitamin K1 (phylloquinone): found in plant foods like leafy greens
• Vitamin K2 (menaquinone): found in animal foods and fermented foods (2Trusted Source)

Vitamin K2 can be further divided into several different subtypes. The most important ones are MK-4 and MK-7.

SUMMARY

Vitamin K was initially discovered as a nutrient involved in blood clotting. There are two forms: K1 (found in plant foods) and K2 (found in animal and fermented foods).  

 

 

 

How do vitamins K1 and K2 work?

Vitamin K activates proteins that play a role in blood clotting, calcium metabolism, and heart health.

One of its most important functions is to regulate calcium deposition. In other words, it promotes the calcification of bones and prevents the calcification of blood vessels and kidneys (3Trusted Source).

Some scientists have suggested that the roles of vitamins K1 and K2 are quite different, and many feel that they should be classified as separate nutrients altogether.

In controlled studies in people, researchers have also observed that vitamin K2 supplements generally improve bone and heart health, while vitamin K1 has no significant benefits (4Trusted Source).

However, more human studies are needed before the functional differences between vitamins K1 and K2 can be fully understood. 

 

 

May help prevent heart disease

Calcium buildup in the arteries around your heart is a huge risk factor for heart disease (5Trusted Source, 6Trusted Source).

Anything that can reduce this calcium buildup may help prevent heart disease. Vitamin K is believed to help by preventing calcium from being deposited in your arteries (3Trusted Source).

In one study spanning 7–10 years, people with the highest intake of vitamin K2 were 52% less likely to develop artery calcification and had a 57% lower risk of dying from heart disease (7Trusted Source).

Another study in 16,057 women found that participants with the highest intake of vitamin K2 had a much lower risk of heart disease — for every 10 mcg of K2 they consumed per day, heart disease risk was reduced by 9% (8Trusted Source).

On the other hand, vitamin K1 had no influence in either of those studies.

However, keep in mind that the studies were observational studies, which cannot prove cause and effect.

The few controlled studies that have been conducted used vitamin K1, which seems to be ineffective (9Trusted Source).

Long-term controlled trials on vitamin K2 and heart disease are needed.

Still, there is a highly believable biological mechanism for its effectiveness and strong positive correlations with heart health in observational studies.

SUMMARY

A higher intake of vitamin K2 is strongly associated with a reduced risk of heart disease. Vitamin K1 appears to be less useful or ineffective.

May help improve bone health and lower your risk of osteoporosis

Osteoporosis — which translates to the phrase “porous bones” — is a common problem in Western countries.

It is seen especially among older women and strongly raises the risk of fractures.

As mentioned above, vitamin K2 plays a central role in the metabolism of calcium, the main mineral found in your bones and teeth.

Vitamin K2 activates the calcium-binding actions of two proteins — matrix GLA protein and osteocalcin, which help to build and maintain bones (10Trusted Source).

Interestingly, there is also substantial evidence from controlled studies that K2 may provide major benefits for bone health.

A 3-year study in 244 postmenopausal women found that those taking vitamin K2 supplements had much slower decreases in age-related bone mineral density (11).

Long-term studies in Japanese women have observed similar benefits, though very high doses were used in these cases. Out of 13 studies, only one failed to show significant improvement.

Seven of these trials, which took fractures into consideration, found that vitamin K2 reduced spinal fractures by 60%, hip fractures by 77%, and all non-spinal fractures by 81% (12Trusted Source).

In line with these findings, vitamin K supplements are officially recommended for preventing and treating osteoporosis in Japan (13Trusted Source).

However, some researchers are not convinced. Two large review studies concluded that evidence to recommend vitamin K supplements for this purpose is insufficient (14Trusted Source, 15).

SUMMARY

Vitamin K2 plays an essential role in bone metabolism, and studies suggest that it can help prevent osteoporosis and fractures.

May improve dental health

Researchers have speculated that vitamin K2 may affect dental health.

However, no human studies have tested this directly.

Based on animal studies and the role vitamin K2 plays in bone metabolism, it’s reasonable to assume that this nutrient affects dental health as well.

One of the main regulating proteins in dental health is osteocalcin — the same protein that is critical to bone metabolism and is activated by vitamin K2 (16Trusted Source).

Osteocalcin triggers a mechanism that stimulates the growth of new bone and new dentin, which is the calcified tissue underneath the enamel of your teeth (17Trusted Source).

Vitamins A and D are also believed to play an important role here, working synergistically with vitamin K2 (18Trusted Source).

 

The bottom line

Vitamin K is a group of nutrients divided into vitamins K1 and K2.

Vitamin K1 is involved in blood coagulation, and vitamin K2 benefits bone and heart health. However, more studies on the roles of vitamin K subtypes are needed.

Some scientists are convinced that people at risk of heart disease should regularly use vitamin K2 supplements. Others point out that more studies are needed before any solid recommendations can be made.

However, it’s clear that vitamin K plays an essential role in body function.

To maintain good health, make sure to get adequate amounts of vitamins K1 and K2 through your diet.

  

Written By

Joe Leech, MS