What is Vitamin MK4? The Essential Guide to Menaquinone-4

October 17, 2025 •

4 min read

Recent studies suggest that vitamin K2, specifically menaquinone-4 (MK4), is crucial for promoting healthy bones and a strong cardiovascular system. Vitamin MK4 is a lesser-known but highly active form of vitamin K that plays a vital role in directing calcium to the right places in the body, preventing arterial calcification, and supporting overall health.

Quick Summary

An overview of vitamin MK4 (menaquinone-4), a key form of vitamin K2. It details its function in promoting bone mineralization, protecting cardiovascular health, and explains its dietary sources, biological role, and differences compared to MK7.

Key Points

MK4 is a Vitamin K2 Subtype: Menatetrenone (MK4) is a specific form of vitamin K2 that is synthesized by animals, including humans, and found in animal-based foods like eggs and meat.
Supports Bone Health: MK4 activates osteocalcin, a protein essential for binding calcium and integrating it into the bone matrix, thereby promoting bone density.
Protects Cardiovascular System: By activating Matrix Gla Protein (MGP) in arterial walls, MK4 helps prevent the calcification of arteries, supporting heart health.
Differs from MK7: Unlike MK7, MK4 has a shorter half-life in the bloodstream and is more concentrated in certain tissues. Levels of MK4 used in some research are significantly higher than typical MK7 levels.
Found in Animal Foods: Rich dietary sources of MK4 include pasture-raised egg yolks, liver, meat, and certain dairy products.
Used for Osteoporosis Research: Higher levels of MK4 have been used in Japan for decades in the context of osteoporosis research and treatment, demonstrating a reduction in fracture risk in studies.

What is Vitamin MK4? Unpacking the Basics

Vitamin MK4, or menaquinone-4, is a subtype of vitamin K2, a fat-soluble vitamin essential for various bodily functions. Unlike vitamin K1, found in leafy green vegetables, and other forms of K2 (like MK7) produced by bacteria, MK4 is synthesized by animal tissues, including humans. It is the most prevalent form of vitamin K2 found in the human body, with significant concentrations in organs such as the pancreas, testes, and arterial walls.

The body produces MK4 by converting vitamin K1 (phylloquinone) absorbed from plant-based foods. However, MK4 is also present in animal products, including eggs, meat, and dairy. Its synthesis within the body and unique distribution to specific tissues suggest it has distinct functions beyond the general role of vitamin K in blood coagulation.

The Biological Role of Menaquinone-4

Beyond its role in blood clotting, MK4 has specific functions related to calcium metabolism and cellular health. Its primary benefits stem from its ability to activate vitamin K-dependent proteins. The two most notable proteins are osteocalcin and Matrix Gla Protein (MGP).

Osteocalcin Activation: Located in bone-forming cells, osteocalcin binds to calcium and is crucial for integrating it into the bone matrix. Activated by vitamin K, it ensures calcium strengthens bones, improving bone density.
Matrix Gla Protein (MGP) Activation: MGP is found in arterial walls and soft tissues. When activated by vitamin K, it acts as a powerful inhibitor of arterial calcification, preventing calcium from building up in arteries and contributing to cardiovascular health.

By ensuring calcium is properly utilized, MK4 supports the skeletal and cardiovascular systems simultaneously. Furthermore, MK4 accumulates in various tissues and has been studied for its potential effects on brain health, inflammation management, and other cellular processes.

Dietary Sources of MK4

While the body can convert K1 to MK4, dietary intake of animal products is the most direct way to get this form of vitamin K2. Key sources include:

Organ Meats: Liver (especially chicken liver) and other organ meats are particularly rich sources of MK4.
Meat: Beef (especially ground beef) and chicken also contain measurable amounts of MK4.
Pasture-Raised Egg Yolks: Eggs from chickens allowed to forage on pasture have higher levels of MK4 compared to conventionally raised chickens.
Butter and Certain Cheeses: These dairy products contain MK4, with levels varying depending on the animal's diet.

Comparison: MK4 vs MK7

While both MK4 and MK7 are important forms of vitamin K2, they differ significantly in their structure, function, and bioavailability. The key distinctions are summarized in the table below.


Feature	Vitamin MK4 (Menaquinone-4)	Vitamin MK7 (Menaquinone-7)
Source	Animal products (meat, eggs, dairy); produced from K1 conversion in the body.	Fermented foods (natto, certain cheeses); produced by bacteria.
Half-Life	Short; cleared from blood within 6-8 hours.	Long; remains available in the body for several days.
Transport	Packaged into triglycerides for transport.	Packaged into cholesterol for more stable transport.
Research Focus	Studied for bone health at higher levels, particularly in Japan.	Effective at supporting systemic benefits at nutritional levels due to its long half-life.
Absorption	Can be poorly absorbed at nutritional levels in some studies.	Highly bioavailable and well-absorbed.

Supplementation Considerations

Due to its short half-life and the levels often required to achieve specific therapeutic effects, MK4 supplementation typically follows a different strategy than MK7. In Japan, for instance, high-level MK4 has been used since 1995 to address osteoporosis, with clinical trials showing a significant reduction in fractures. Lower levels have also been studied for their effects on bone markers. While MK7 is generally seen as more efficient for systemic, long-term bone and cardiovascular benefits at lower, daily levels due to its longer half-life, MK4 is still a valid option, particularly for targeted, high-level applications. For those on blood thinners like warfarin, supplementation with any form of vitamin K requires careful medical supervision.

Potential Risks and Considerations

While generally safe, excess vitamin K can pose risks, especially in specific conditions. In healthy individuals, higher-level MK4 does not increase the risk of blood clots because once clotting factors are fully activated, excess vitamin K is used for other purposes. However, those with pre-existing conditions or taking certain medications must exercise caution.

Interactions with Blood Thinners: Vitamin K supplementation directly counteracts the effects of anticoagulants like warfarin, potentially increasing the risk of blood clots.
Liver Disease: For those with severe liver disease, high levels of vitamin K may worsen existing clotting problems.
Gastrointestinal Side Effects: Some people may experience mild side effects like nausea or abdominal pain.

Conclusion: The Unique Role of Vitamin MK4

Vitamin MK4 is a distinct and biologically active form of vitamin K2 with important functions related to bone strength and cardiovascular health. Found in animal products and produced within the body, it works by activating key proteins that regulate calcium utilization. While it differs from MK7 in bioavailability and half-life, particularly at nutritional levels, high-level MK4 has a long history of use for addressing osteoporosis in Japan, showcasing its potent effects. A balanced diet including MK4-rich animal products, alongside consideration of MK7-rich fermented foods, offers a comprehensive approach to maximizing the benefits of vitamin K2 for long-term health.

Learn more about the differences between MK4 and MK7 at NBI Health.

Frequently Asked Questions

The primary function of vitamin MK4 is to activate specific proteins, such as osteocalcin and Matrix Gla Protein (MGP), which regulate calcium utilization. This process is crucial for promoting bone mineralization and preventing calcium buildup in arteries.

The body primarily obtains vitamin MK4 from two sources: dietary intake of animal products like eggs, meat, and dairy, and endogenous synthesis, where the body converts vitamin K1 from plant sources into MK4.

MK4 differs from MK7 mainly in its half-life and sources. MK4 has a short half-life and is found in animal products, while MK7 has a long half-life and is sourced from fermented foods like natto.

While MK4 is present in animal products, achieving some of the higher levels used in research is not feasible through diet alone. However, a balanced diet including animal foods contributes to your overall MK4 status.

Individuals taking blood-thinning medications like warfarin should be cautious with MK4 supplements, as vitamin K can interfere with these drugs. Those with severe liver disease should also consult a doctor.

Common benefits of MK4 supplementation often discussed include improved bone mineral density, reduced risk of arterial calcification, and support for bone marrow and cognitive health, particularly in studies using higher levels.

Clinical trials have demonstrated the safety of some higher levels of MK4 in healthy individuals, with no reported increase in blood clot risk. However, this should always be done under the guidance of a healthcare professional.

In Japan, a higher level of MK4 has been explored for osteoporosis in clinical settings since 1995, and numerous studies have shown it can reduce fracture risk.