Other Names for Vitamin K
Yes, there are several other terms for vitamin K, reflecting its different forms and its original discovery. These names, including phylloquinone and menaquinones, refer to different types of this fat-soluble vitamin. The story begins with its discovery in 1929 by Henrik Dam, a Danish biochemist who named it 'Koagulations vitamin' due to its essential role in blood coagulation. The 'K' in its name is a direct reference to this German word.
The Two Primary Natural Forms
Vitamin K is not a single compound but a family of structurally similar compounds known as naphthoquinones. The two most important naturally occurring forms are Vitamin K1 and Vitamin K2, each with its own set of alternate names.
- Vitamin K1 (Phylloquinone/Phytonadione): This form is primarily found in green leafy vegetables and is the major dietary source of vitamin K for humans. Its other names include phylloquinone and phytonadione.
- Vitamin K2 (Menaquinones/MK-n): This form refers to a group of compounds produced by bacteria, both in the human gut and in fermented foods. Menaquinones are designated with an MK-n, where 'n' indicates the number of repeating isoprenoid units in the side chain. Important examples include MK-4 and MK-7, which have gained attention for their role in bone and heart health.
Synthetic and Historical Terms
- Menadione (Vitamin K3): This is a synthetic form of vitamin K. However, it is no longer used in human supplements due to toxicity concerns observed in lab studies.
- Antihemorrhagic factor: Another historical and functional term for vitamin K, highlighting its ability to prevent bleeding.
- Koagulations vitamin: As mentioned, this was the original name given by Danish scientists, which is the origin of the letter K.
The Function and Sources of Each Vitamin K Form
The different forms of vitamin K are absorbed and utilized differently by the body, leading to varying functions beyond blood clotting.
Functions of Vitamin K
Both K1 and K2 are essential coenzymes for the gamma-glutamyl carboxylase enzyme, which activates proteins involved in three key physiological processes.
- Blood Coagulation: Vitamin K is crucial for the liver to synthesize proteins necessary for blood clotting, including factors II, VII, IX, and X. Without vitamin K, blood clotting would be seriously impaired.
- Bone Metabolism: The vitamin is a vital cofactor for activating osteocalcin, a protein that binds calcium to the bone matrix. Higher vitamin K intake is associated with stronger bones and a lower risk of hip fractures.
- Cardiovascular Health: Vitamin K activates Matrix Gla protein (MGP), which helps prevent the calcification or hardening of arteries.
Dietary Sources
- Phylloquinone (K1): Found abundantly in green leafy vegetables. The bioavailability of K1 from food is lower than from supplements but is significantly improved when consumed with fat.
- Menaquinones (K2): Dietary sources of K2 include fermented foods like nattō (fermented soybeans), which is a particularly rich source of MK-7, as well as cheese and other animal products. While gut bacteria produce some K2, the amount and form available for absorption are still under investigation.
Comparison Table: Vitamin K1 vs. Vitamin K2
| Feature | Vitamin K1 (Phylloquinone) | Vitamin K2 (Menaquinones) |
|---|---|---|
| Primary Source | Green leafy vegetables, vegetable oils | Fermented foods (nattō), animal products |
| Metabolic Location | Primarily taken up by the liver | Distributed more widely to extrahepatic tissues |
| Half-Life | Short (~1–2 hours) | Long (MK-7 is ~72 hours) |
| Key Functions | Blood coagulation | Bone and cardiovascular health, energy metabolism |
| Bioavailability | Tightly bound to plant tissue, lower absorption from food | Good bioavailability from food sources |
Potential for Deficiency
Vitamin K deficiency is rare in healthy adults with adequate dietary intake, but certain populations are at higher risk.
- Newborns: Infants are born with very low levels of vitamin K and poor placental transfer. A vitamin K shot is routinely given at birth to prevent a potentially life-threatening bleeding disorder known as Vitamin K Deficiency Bleeding (VKDB).
- Individuals with Malabsorption: People with gastrointestinal disorders such as cystic fibrosis, celiac disease, or short bowel syndrome may not absorb vitamin K properly.
- Long-Term Antibiotic Use: Extended use of antibiotics can destroy the gut bacteria that produce vitamin K, potentially leading to lower status.
Conclusion
In summary, while vitamin K is a single family of fat-soluble compounds, it has several other terms that refer to its specific forms. The primary natural forms are phylloquinone (K1) and menaquinones (K2), which have distinct dietary sources, absorption rates, and functions in the body. The historical name, 'Koagulations vitamin,' explains the origin of the letter 'K' and its fundamental role in blood clotting. Understanding these different terms is crucial for interpreting nutritional information and appreciating the broader roles of vitamin K in bone and cardiovascular health. While most people obtain sufficient vitamin K from their diet, awareness of its various forms can help at-risk individuals and those on certain medications ensure adequate intake. For more information on dietary sources, consult the NIH Office of Dietary Supplements website.
Is there another term for vitamin K?
- Phylloquinone and Menaquinones: Vitamin K is not a single entity but a group of compounds, with the main natural forms being phylloquinone (Vitamin K1 from plants) and menaquinones (Vitamin K2 from bacteria and animal products).
- Koagulations vitamin: The letter 'K' is derived from this original German term, given to the vitamin by its discoverer, Henrik Dam, due to its role in blood coagulation.
- Blood clotting and bone health: The key functions of vitamin K include supporting the production of blood-clotting factors and activating proteins necessary for bone metabolism.
- K1 vs. K2: While both forms support overall vitamin K function, they differ in their sources, absorption, half-life, and distribution, with K2 playing a more significant role in extrahepatic tissues like bones and arteries.
- Dietary Sources: Excellent sources include green leafy vegetables for K1 and fermented foods like nattō and some animal products for K2.
