The Mystery of Vitamin K and its MKs

The Mystery of Vitamin K and its MKs

Vitamin K is one of the few outcast Vitamins, that really aren’t vitamins at all! There are a number of Vitamin Ks to be explored each providing beneficial health properties to the body. Fat soluble Vitamin K was named as such by Danish Scientist Henrik Dam.

It was named simply because it was the next available letter not already allocated to a vitamin . It was by lucky coincidence that in German its name correlated with its function, I.e Koagulation, meaning coagulation in English.

The Science Behind Its Structure

There are 3 kinds of Vitamin K, these are:

  • Vitamin K1, Phylloquinone. This structure is found naturally in green vegetables that undergo photosynthesis. This is processed and resides in the liver for when it is required.
  • Vitamin K2, Menaquinone. This is the kind of Vitamin K we can make ourselves. The healthy gut bacteria produces very small amounts of Vitamin K that can supply blood vessels and bones.
  • Vitamin K3, Menadione. This is a synthetic form which must be taken in moderation [1].

The technical name for the natural K1 and K2 structures are 2-methyl-3-hydroxyl-1,4-naphthoquinone, however, unless you are in laboratory it will almost never be referred to as this. The structure of Vitamin K1, is very similar to chlorophyll, the plant pigment which creates the green colour. This isn’t the only role of chlorophyll, it is also responsible for photosynthesis the process that feeds the plant.

Vitamin K2 is produced by gut bacteria species such as Bacteriodes and Enterobacteria. Vitamin K2 is often followed by MK and a number such as MK1, MK4, MK7 or MK9, this refers to its structure. Vitamin K2 is made up of a ring structure with a chain of carbon repeating units called ‘isoprene units’. The number of the isoprene units branching from the chain dictates the number that follows the MK, e.g MK7 has 7 isoprene units branching from the central ring structure [2].

Delve into its History...

The original discovery of Vitamin K was in 1929. Although, it was less of a discovery and more a ‘stumble upon’ moment. Henrik Dam, Danish Scientist was investigating the role of cholesterol on the body, however he couldn't use humans in this so he chose chickens. His method was to feed the hens a completely fat-free diet, thus unwittingly excluding Vitamin K. In a matter of weeks the hens became haemorrhagic. He then found that feeding the hens alfafa or fishmeal would prevent this. Little did he know that both of these food sources were rich in Vitamin K [2]. Then 10 years later in 1939 chemist Almquist discovered the link between bacteria and Vitamin K. The mystery was unraveled.

What is it used for in the body?

There are a very few uses of Vitamin K in our body however what it is used for is vitally important.

Supporting your Bones!

This was discovered when poor diets lacking Vitamin K generated symptoms of brittle bones. It’s thought that Vitamin D and Vitamin K have a synergistic relationship on bone mineral density. We all know the link between Vitamin D and Calcium, but do we know the link between Vitamin K and Calcium? Vitamin K is thought to have much the same effect as Vitamin D, positively increasing the prevalence of Calcium available for bone mineralization. One study found that adequate intakes of Vitamin K reduced fractures and increased bone mineral density in osteoarthritic patients [3].

Clotting your Blood!

Vitamin K is the primary nutrient responsible for healthy blood clotting. It does so by increasing the synthesis of amino acids, γ–carboxyglutamic acids otherwise known as Gla. Gla is found in smooth muscle, cartilage and bone. This is produced by adding carboxyl groups to the amino acids Glutamate. This production cannot occur without Vitamin K. To clot the blood we used prothrombin factor (factor II), factor VII, IX, X. Prothrombin Factor and Factor VII in particular are made up of 10 of these Gla molecules, thus without it we are unable to clot [2,4].

Does Deficiency exist?

Technically there is no term or disease classified as Vitamin K deficiency. However, there are symptoms that occur when Vitamin K is not sufficient in the diet, these are:

  • Excessive bleeding, slow to clot
  • Liver problems
  • Heavy Menstrual bleeding
  • Decreased bone mineralization

One disease called hypoprothrombinaemia, which leads to excessive bleeding is thought to be benefited by adequate intakes of Vitamin K. Another disorder thought to benefit from Vitamin K is Osteoporosis. This effect is best seen on post menopausal women with decreased bone density. Vitamin K is particularly essential in newborns. Although the deficiency is rare, it is so dangerous that as a precaution all babies are given a shot of Vitamin K after birth [4].

There is no established recommended intake for Vitamin K, but as a rough guideline you are advised to consume 0.001mg/kg of body weight a day. For example,

A 75kg human would consume = 75*0.001= 0.075mg

What are the best food sources?

The best sources of Vitamin K1 are from leafy green vegetables such as:

  • Kale
  • Spinach
  • Collard Greens
  • Parsley
  • Coriander
  • Broccoli
  • OR
  • Natto (Fermented Soy) [5]

This is best for the health of the blood. However, the best source for bones is Vitamin K2. This can be sourced best from a supplement. The best supplements for this are Vitamin K2 MK4, MK7 or MK9. Why not try these paired with Vitamin D to really boost the health of your bones.

  1. Mercola.J. (2004). 10 Important Facts About Vitamin K That You Need to Know . Available:
  2. Truswell.S. (2012). Vitamins D and K. In: Mann,J. Truswell,S.Essentials of Human Nutrition. 4th ed. Oxford: Oxford University Press. Pg. 250-253
  3. Weber.P. (2001). Vitamin K and Bone Health. Nutrition. 17 (1024), Pg. 11-12.
  4. UMM. (2016). Vitamin K. Available:
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