Vitamin K is a fat-soluble vitamin that is required to play the two most essential roles in the body - blood clotting and bone metabolism.
Vitamin K exists in two forms in our body - Vitamin K1 and K2. Vitamin K1 is also known as phylloquinone and we primarily get this form from plant-based vitamin K rich foods like dark green leafy vegetables. Whereas, vitamin K2 or menaquinone is present in animal foods as well as fermented foods. Our gut bacteria also produce vitamin K2.
Our body utilises both these forms of vitamin K to synthesise prothrombin which is a protein required for blood clotting and keeping the heart-healthy. In addition, vitamin K also plays a critical role during energy metabolism by acting as a coenzyme.
Prothrombin is required in the blood clotting and wound healing process. In case our body lacks vitamin K then we will bleed continuously during injury, wounds, bruises or surgery. The vitamin K dependent coagulation proteins are formed in the liver and these factors help in blood clotting.
Apart from this, we need vitamin K to keep our bones strong and healthy. The deficiency of vitamin K increases the likelihood of osteoporosis and frequent fractures. Vitamin K is needed for the gamma-carboxylation of osteocalcin, which is a protein required to increase the utilisation of calcium in our bones. A study conducted in Japan found that elderly Japanese men who consume Natto as a regular part of their diet have better bone density. Natto is a fermented Japanese food rich in vitamin K. People had a reduced likelihood of developing osteoporosis and better bone health.
Vitamin K also keeps our heart healthy by keeping our blood vessels healthy. It prevents calcium from getting deposited across the vessels hence reducing the risk of many cardiovascular disorders. This is because vascular calcification reduces the elasticity of the aorta and causes coronary artery disease.
Since vitamin K is a fat-soluble vitamin hence it requires fat in our body to get metabolised and absorbed in the small intestine. It is primarily found in the liver, bone, brain, heart and pancreas. Low levels of vitamin K are also associated with poor brain health and a high probability of neurological diseases like Alzheimer. This is because vitamin K dependent proteins are required for sphingolipid metabolism in our nervous system. Studies exhibit a high risk of vitamin K deficiency with poor memory, anxiety and depression.
Hence, vitamin K is very important to keep our bones, heart and other organs healthy. Its deficiency increases bleeding, can cause gastrointestinal disorders, poor bone health and memory loss. Although vitamin K deficiency is not very common it might develop among people on medications, antibiotics, celiac disease, ulcerative colitis and cholestasis.
As per ICMR, the daily recommended allowance of vitamin K is 55 micrograms per day for adults. Therefore, the diet should include plenty of vitamin K rich foods like kale, lettuce, broccoli, natto, cabbage, spinach, eggs, chicken, fatty fish and organ meats like liver.
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Ferland G. (2013). Vitamin K and brain function. Seminars in thrombosis and hemostasis, 39(8), 849–855. https://doi.org/10.1055/s-0033
DiNicolantonio JJ, Bhutani J, O'Keefe JH.(2015).The health benefits of vitamin K.Open Heart,2,e000300. doi: 10.1136/openhrt-2015-000300