What Does Vitamin K Produce for Your Body?

December 17, 2025 •

3 min read

Vitamin K was discovered in the 1930s due to observations of uncontrolled bleeding in chicks fed a deficient diet, a discovery that highlighted its crucial role in coagulation. While the body does not create vitamin K itself, this fat-soluble nutrient acts as a vital co-factor, enabling the body to produce specific, essential proteins required for blood clotting, bone mineralization, and cardiovascular health.

Quick Summary

Vitamin K is essential for the production of critical proteins necessary for blood clotting, including factors II, VII, IX, and X. It also activates proteins like osteocalcin for bone mineralization and matrix Gla protein (MGP) for inhibiting arterial calcification.

Key Points

Activates Clotting Proteins: Vitamin K is crucial for activating factors II, VII, IX, and X in the liver, which are necessary for blood to clot and prevent excessive bleeding.
Enhances Bone Mineralization: It produces and activates osteocalcin, a protein that binds calcium to the bone matrix, which is essential for building strong, healthy bones.
Inhibits Arterial Calcification: The vitamin is required for the activation of Matrix Gla Protein (MGP), which prevents calcium from accumulating in the arteries and soft tissues.
Supports Cardiovascular Health: By preventing arterial calcification, vitamin K, particularly the K2 form, helps maintain arterial flexibility and reduces the risk of heart disease.
Relies on Dietary Sources: The two main forms, K1 (phylloquinone) and K2 (menaquinones), come from different dietary sources, including green leafy vegetables and fermented foods respectively.
Operates via a Recycling Cycle: For continuous function, vitamin K undergoes a metabolic cycle where enzymes convert its oxidized form back into its active, reduced state.
Deficiency Leads to Bleeding Risks: A severe vitamin K deficiency can result in serious bleeding problems, which is why newborns are routinely given a dose at birth.

The Core Function: Activating Essential Proteins

Vitamin K doesn't directly produce substances but acts as a coenzyme for gamma-glutamyl carboxylase (GGCX), an enzyme that activates specific proteins through a process called carboxylation. These activated, or carboxylated, proteins then perform crucial functions in the body. Without enough vitamin K, these proteins remain inactive, leading to various health issues.

Vitamin K's Role in Blood Coagulation

The best-known function of vitamin K is its involvement in producing proteins needed for blood clotting. It's called the "clotting vitamin" because it's essential for activating several key coagulation factors produced in the liver, specifically factors II (prothrombin), VII, IX, and X. It also helps synthesize anticoagulant proteins C and S. Severe deficiency can cause excessive bleeding, known as vitamin K deficiency bleeding (VKDB), especially in newborns.

The Production of Proteins for Bone Health

Vitamin K is also vital for strong bones, primarily by activating osteocalcin, a protein made by osteoblasts. Once activated by vitamin K, osteocalcin binds calcium to the bone matrix, which is crucial for bone mineralization and strength. Low vitamin K levels have been linked to low bone density and increased fracture risk, particularly in older adults.

Protecting Cardiovascular Health

An important function of vitamin K, especially K2, is protecting the cardiovascular system from calcification. Vitamin K activates Matrix Gla Protein (MGP), a potent inhibitor that prevents calcium from depositing in artery walls and other soft tissues. Adequate intake of vitamin K2 has been associated with a lower risk of coronary heart disease and improved arterial stiffness. Insufficient vitamin K can lead to calcium buildup in arteries, contributing to atherosclerosis.

The Two Main Forms of Vitamin K

Naturally, there are two main forms of vitamin K with different sources and functions.

Vitamin K1 (Phylloquinone): Found mainly in green leafy vegetables, it is the primary dietary source and is mostly used for activating clotting factors in the liver.
Vitamin K2 (Menaquinones): Produced by gut bacteria and found in fermented foods and animal products, K2 is better absorbed and lasts longer than K1. It is particularly important for activating proteins in bones and arteries like MGP and osteocalcin.

Dietary Sources of Vitamin K

A balanced diet ensures sufficient vitamin K from both K1 and K2 sources.

Common Sources of Vitamin K1 (Phylloquinone):

Kale
Spinach
Broccoli
Brussels sprouts
Cabbage
Lettuce
Vegetable oils like soybean and canola oil

Common Sources of Vitamin K2 (Menaquinones):

Natto (fermented soybeans)
Organ meats
Meat, eggs, and dairy products

Comparison of Vitamin K1 and Vitamin K2


Feature	Vitamin K1 (Phylloquinone)	Vitamin K2 (Menaquinones)
Primary Source	Green leafy vegetables	Fermented foods, animal products, gut bacteria
Chemical Structure	Contains one phytyl side chain	Contains multiple isoprenoid side chains
Half-Life	Shorter half-life	Longer half-life and greater bioavailability
Primary Function	Activating hepatic (liver) clotting factors	Activating extra-hepatic proteins for bone and heart health
Bioavailability	Poorly absorbed without fat	Absorbed more readily
Key Protein Activation	Clotting Factors II, VII, IX, X	MGP, Osteocalcin, and others

The Vitamin K Cycle

Vitamin K functions through a recycling process called the vitamin K cycle, involving enzymes GGCX and vitamin K epoxide reductase (VKOR). GGCX uses reduced vitamin K, which is then oxidized. VKOR regenerates the reduced form, allowing the cycle to continue. Warfarin, an anticoagulant, inhibits VKOR, reducing activated clotting factors.

Conclusion

To answer the question, what does vitamin K produce? It is a crucial coenzyme that activates essential proteins for blood clotting, bone mineralization, and preventing arterial calcification. These activated proteins are vital for preventing excessive bleeding, maintaining bone health, and supporting cardiovascular function. Getting enough vitamin K from both leafy greens (K1) and fermented foods or animal products (K2) is key for overall health and well-being.

Frequently Asked Questions

Vitamin K acts as a crucial coenzyme that produces and activates specific proteins required for blood clotting, bone mineralization, and the prevention of arterial calcification.

No, vitamin K does not produce blood clots directly. Instead, it is essential for producing the active forms of the proteins, known as clotting factors, that are involved in the blood coagulation process.

Vitamin K produces and activates the protein osteocalcin, which binds calcium to the bone matrix. This process is necessary for healthy bone mineralization and density.

Vitamin K is essential for activating Matrix Gla Protein (MGP), which actively inhibits the buildup of calcium in arteries and soft tissues, thereby protecting against calcification and arterial stiffness.

Vitamin K1 (phylloquinone) is found mainly in green leafy vegetables and is primarily used for blood clotting proteins in the liver. Vitamin K2 (menaquinones) is found in fermented foods and animal products and is more active in extra-hepatic tissues like bones and arteries.

Newborns have very low levels of vitamin K, putting them at risk for a life-threatening bleeding disorder known as Vitamin K Deficiency Bleeding (VKDB). A vitamin K shot is administered at birth to prevent this condition.

While green vegetables provide plenty of vitamin K1, they are not a significant source of the K2 form. To obtain adequate amounts of both, a varied diet that includes fermented foods or animal products is necessary.