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Vitamin K

life science Maturity 5-7 Next article →

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"text": "Vitamin K is a family of structurally similar, fat-soluble vitamers. These molecules are essential for several critical biological functions. The name \"K\" comes from the Danish word *koagulation*, which means coagulation. This refers to the process of blood clotting.

Phylloquinone structure
Phylloquinone structure

Beyond clotting, vitamin K helps control how calcium binds to bones and other tissues. It is found in many foods and is also sold as a dietary supplement. It can even be used as a prescription medication for specific medical needs.\n\nTo understand how it works, we must look at the molecular level. The body uses vitamin K to modify certain proteins called Gla proteins. This process is called carboxylation. An enzyme called gamma-glutamyl carboxylase performs this task. In this reaction, vitamin K acts as a cofactor, which is a helper molecule.

K1 vitamin Mechanism of Action
K1 vitamin Mechanism of Action

In the liver, the vitamin is used as an intermediate called VKH2. This intermediate helps deprotonate a glutamate residue. Afterward, the vitamin is reprocessed into vitamin K through a vitamin K oxide intermediate. This carboxylation allows the proteins to chelate, or bind, to calcium ions. Without this process, the proteins cannot function correctly.\n\nThe vitamin K family includes different types of vitamers. The two most common natural types are vitamin K1 and vitamin K2.

Menaquinone
Menaquinone

Vitamin K1 is also known as phylloquinone. It is produced by plants and is directly involved in photosynthesis. Vitamin K2 is known as menaquinone. This type consists of several chemical subtypes. These subtypes differ by the length of their carbon side chains. Two well-studied subtypes are menaquinone-4 (MK-4) and menaquinone-7 (MK-7). While animals can convert K1 into the MK-4 variant, other K2 forms are produced by bacteria.\n\nDifferent sources provide these vitamers in different amounts. Vitamin K1 is found in high concentrations in green leafy vegetables. For example, boiled collard greens provide 530 μg per measure. Spinach and turnip greens are also very rich sources.

Phytomenadione (vitamin K1)
Phytomenadione (vitamin K1)

Vitamin K2 comes primarily from animal-sourced foods. Poultry and eggs are much better sources than beef, pork, or fish. An interesting exception is nattō. Nattō is made from fermented soybeans. Bacteria produce a very high amount of the MK-7 variant during anaerobic respiration. In nattō, MK-7 makes up about 90% of the vitamin K2 content.\n\nHealth organizations set specific dietary guidelines known as adequate intakes (AIs). In the United States, the National Academy of Medicine provides these values. For adult men, the AI is 120 μg/day. For adult women, the AI is 90 μg/day. Pregnant and lactating women also require 90 μg/day. For infants up to 12 months, the AI is between 2.0 and 2.5 μg/day. Children between ages 1 and 18 have requirements that increase from 30 to 75 μg/day. Interestingly, there is no established upper limit for vitamin K intake. This is because there is not enough human data regarding adverse effects from high doses.\n\nVitamin K deficiency can lead to serious health issues. Because it is vital for blood clotting, a lack of vitamin K can cause uncontrolled bleeding. This is especially a risk for

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🖼️ Images & Media (5)
File:Vitamina K 20220202 122653.jpg
Vitamina K 20220202 122653.jpg
File:Phylloquinone structure.svg
Phylloquinone structure.svg
File:Menaquinone.svg
Menaquinone.svg
File:Phytomenadione (vitamin K1).jpg
Phytomenadione (vitamin K1).jpg
File:K1 vitamin Mechanism of Action.svg
K1 vitamin Mechanism of Action.svg
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