Understanding the Different Names and Forms: Is there another name for vitamin K?

October 16, 2025 •

3 min read

Over 90% of all vitamin K consumed by humans is phylloquinone, or vitamin K1, found in plant foods. The question, 'Is there another name for vitamin K?' is more complex than a simple yes or no, as it refers to a family of compounds with different names and distinct functions in the body.

Quick Summary

Vitamin K is a group of fat-soluble compounds, with the main types being K1 (phylloquinone) and K2 (menaquinones). They have specific roles in blood clotting, bone health, and cardiovascular function, and come from different dietary sources.

Key Points

Not a single vitamin: Vitamin K is a group of fat-soluble compounds, with phylloquinone (K1) and menaquinones (K2) being the primary forms.
Phylloquinone is Vitamin K1: This form is found mainly in green leafy vegetables and is critical for liver function and blood clotting.
Menaquinone is Vitamin K2: Produced by bacteria and found in fermented foods and animal products, K2 supports bone and cardiovascular health.
Warfarin and Vitamin K interaction: Anticoagulant medications like warfarin block the activation of vitamin K, so patients on this medication must maintain consistent vitamin K intake.
Dietary sources differ: K1 comes from plants, while K2 is sourced from fermented and animal products, requiring a varied diet for complete intake.
Toxic synthetic form: Menadione (K3) is a synthetic version that is unsafe for human consumption and is no longer used in supplements.

Vitamin K is not a single compound but a collection of fat-soluble vitamins that play critical roles in the human body. While most people are familiar with the general term, understanding its different names and forms is essential for comprehending its nutritional impact. This guide explores the different names for vitamin K, its major forms, and how they contribute to your overall health.

The Two Main Forms of Vitamin K

There are two naturally occurring forms of vitamin K, each with its own specific names and roles.

Vitamin K1: Phylloquinone

Found predominantly in green leafy vegetables, phylloquinone, or vitamin K1, is the primary source of dietary vitamin K for most people.

Phylloquinone: This is the botanical name for vitamin K1, derived from its presence in plants, particularly within the chloroplasts involved in photosynthesis.
Phytonadione: This is a synthetic form of vitamin K1 often used in dietary supplements and medical treatments, such as for newborns to prevent bleeding.

Vitamin K2: Menaquinones

Menaquinones, or vitamin K2, are a family of compounds primarily produced by bacteria and found in fermented foods and some animal products. They are transported to extrahepatic tissues like bones and arteries, giving them a distinct function from vitamin K1.

MK-4 to MK-13: Menaquinones have several subtypes, designated by the number of their isoprenoid side-chain units (e.g., MK-4, MK-7).
Menaquinone: This is the general name for vitamin K2 compounds. MK-4 is produced by the body from K1, while others like MK-7 are primarily from bacterial synthesis.

Menadione (Vitamin K3): The Synthetic and Toxic Form

In addition to the natural forms, menadione, sometimes called vitamin K3, is a synthetic precursor. However, due to its toxicity, it is no longer used in supplements or fortified foods for humans. It has been shown to cause liver toxicity and hemolytic anemia.

The Vital Functions of Vitamin K

Vitamin K's roles extend beyond its different names, proving crucial for several physiological processes.

Blood Coagulation

Vitamin K's most well-known function is its role in blood clotting.

Acts as a cofactor for an enzyme that activates several clotting factors (II, VII, IX, and X) in the liver.
The name itself is derived from the German word for coagulation, Koagulationsvitamin.
Medications like warfarin work by inhibiting this process, requiring patients to carefully monitor their vitamin K intake.

Bone and Cardiovascular Health

Beyond clotting, vitamin K is essential for bone mineralization and cardiovascular health.

Activates Proteins: It activates proteins like osteocalcin, which binds calcium to the bone matrix, and Matrix Gla Protein (MGP), which inhibits soft tissue calcification, including in the arteries.
Health Benefits: Some studies suggest that K2, in particular, may offer greater benefits for bone mineral density and arterial health, although more research is ongoing.

Comparison of Vitamin K1 vs. Vitamin K2

While both forms contribute to vitamin K activity, their origins, function, and bioavailability differ significantly.


Feature	Vitamin K1 (Phylloquinone)	Vitamin K2 (Menaquinone)
Primary Sources	Green leafy vegetables (kale, spinach), vegetable oils	Fermented foods (natto, some cheeses), animal products (egg yolk, meat)
Produced By	Plants during photosynthesis	Gut bacteria and some animal sources
Main Function	Primarily used by the liver for blood clotting factors	Transported to extrahepatic tissues, supporting bone and cardiovascular health
Absorption/Retention	Poorly absorbed from plant sources; quickly cleared from the blood	May be better absorbed and stays in the body longer
Subtypes	One main form (Phylloquinone)	Multiple subtypes (MK-4 to MK-13)

Food Sources for a Vitamin K-Rich Diet

Incorporating a variety of foods is the best way to ensure adequate intake of both vitamin K1 and K2.

Vitamin K1-rich foods:

Spinach
Kale
Broccoli
Brussels sprouts
Cabbage
Soybean and canola oil

Vitamin K2-rich foods:

Natto (fermented soybeans)
Hard and soft cheeses
Egg yolks
Chicken and beef liver

Conclusion

In conclusion, while there is no single another name for vitamin K, its true identity lies in its diverse forms: phylloquinone (K1) and menaquinones (K2). Understanding these different names is crucial for appreciating their distinct roles in blood clotting, bone health, and cardiovascular function. By consuming a balanced diet rich in green leafy vegetables, fermented foods, and certain animal products, you can ensure a consistent intake of both essential vitamin K forms. As always, consulting with a healthcare provider is recommended, especially for individuals on anticoagulant medications like warfarin, where dietary intake must be carefully managed to maintain the drug's effectiveness. For further reading on the science behind Vitamin K, explore reputable resources like the NIH Office of Dietary Supplements.

Frequently Asked Questions

Phylloquinone is one of the main forms of vitamin K, specifically known as vitamin K1. Vitamin K is a generic name for a family of compounds, including phylloquinone and menaquinones (K2).

The primary function of phylloquinone is to help the liver produce clotting factors essential for blood coagulation. It is the form of vitamin K most responsible for stopping bleeding.

Menaquinones (vitamin K2) are found in fermented foods like natto and in animal products such as egg yolks, meat, and certain cheeses. They are also produced by bacteria in the human gut.

Menaquinones are particularly important for bone and cardiovascular health. They activate proteins that help bind calcium in bones and prevent its buildup in arteries, contributing to bone strength and heart health.

A vitamin K deficiency can lead to increased bruising and bleeding problems because the blood does not clot properly. In severe cases, it can weaken bones and increase the risk of fractures.

Phytonadione is a synthetic form of vitamin K1 that is sometimes used in supplements and medical settings. Menadione (K3) is another synthetic form that is not considered safe for human supplements due to toxicity.

Warfarin, an anticoagulant medication, works by blocking the activation of vitamin K in the body. For patients on warfarin, maintaining a consistent daily intake of vitamin K from food and supplements is critical to ensure the medication's effectiveness.