What does Vitamin K do?

Vitamin K is possibly the least known vitamin, yet is just as vital as the other 13 vitamins in maintaining a healthy body. This article will explore what vitamin...
Kale, delicious!

Vitamin K is possibly the least known vitamin, yet is just as vital as the other 13 vitamins in maintaining a healthy body. This article will explore what vitamin K is and does, and where you can find it in your diet.


Role of Vitamin K in the body

Vitamin K is a fat soluble vitamin and so is stored relatively easily by the body, which makes sever deficiency rare. Vitamin K2 plays an important role in bone health, and prevents the calcium in the bones being re-absorbed. This ensures bone density does not decrease and become porous – keeping them strong. This is of particular importance for high risk groups for osteoporosis such as women over the age of 40.

Dietary vitamin K is usually obtained from in the plant form, which is called vitamin K1, and needs to be converted into K2 by the body before it can be used. Vitamin K2 is essential for post-translational modification of proteins which is needed for blood coagulation (blood clotting). Without these proteins the bleed time for a wound can be very long (and in extreme circumstances may not even stop), which may result in sever blood loss. Vitamin K2 has also shown an ability to reduce oxidative stress on the body, but it is not an antioxidant itself, suggesting it does this via an indirect method such as increasing the levels of some antioxidant enzymes.


Foods high in Vitamin K

Green leafy vegetables are high in vitamin K1 (vegetable form of vitamin K). Kale is particularly high in vitamin K1, with only 10g providing you with 100% your RDA (80mcg). Some common probiotic bacteria are capable of producing vitamin K1 and converting K1 to K2 in the large intestine, which reduced the emphasis on dietary requirements.


Vitamin K Deficiency

Although vitamin K deficiency is rare it can have detrimental effect on health. In most cases sever vitamin K deficiency will only arise if you have a damaged intestine or disrupted micro-flora as this effects absorption and production of usable vitamin K. Vitamin K deficiency is characterised by uncontrollable bleeding where damage has occurred, risk of massive blood loss, stomach pains and weak or malformation of bone. Unlike many vitamin deficiencies, some damage from vitamin K deficiency cannot be reversed by adding the vitamin to the diet.


Vitamin K Overdose

It is incredibly hard to overdose on vitamin K, and the body is able to regulate circulating levels with ease meaning excess vitamin K is simply excreted in urine. However, in recent years there have been a small number of vitamin K over-dosages from people trying to strengthen their bones and taking large amount of supplements. Symptoms of vitamin K overdose include diarrhea, skin rash, vomiting and anemia. The dosage required for these symptoms is unconfirmed as it is so rare, and it is extremely difficult to obtain these levels through supplementation and impossible to through diet.



Vitamin K is essential for maintaining blood health and bone health. It also plays a vital role in production of various proteins. Deficiency of vitamin K is rare because we are able to store it in our body and our probiotics can synthesise it in our digestive system meaning serious deficiency is only found in people who have been on antibiotics or who have had a stomach operation. If you want to increase your vitamin K consumption, it is abundant in dark leafy greens such as kale.

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