Vitamin K is a fat-soluble vitamin required by the body for a variety of functions. Vitamin K is synthesized by both plants and certain types of bacteria. Since vitamin K is available in a variety of foods and is produced by bacteria in the stomach, the majority of Americans meet daily vitamin K requirements. However, certain medications or conditions may lead to vitamin K deficiency.
Vitamin K Functions
Vitamin K primarily functions in supporting the body's blood clotting processes, also known as coagulation. Vitamin K participates in the production of four out of the 13 blood clotting proteins in the coagulation cascade, according to the Harvard School of Public Health. The coagulation cascade is a series of steps required to form a blood clot and stop bleeding. Vitamin K also activates calcium which binds a variety of vitamin-K dependent clotting factors. Vitamin K may also play a role in supporting healthy bones as it helps bones use calcium during bone mineralization or the process of building bones.
Sources
Vitamin K is found in a variety of foods or available in dietary supplements, but a significant amount is also made by the body. The three types of vitamin include vitamin K1, K2 and K3. Vitamin K1 is found primarily from food sources such as green, leafy vegetables, cabbage and cauliflower, certain vegetable oils, liver, eggs and milk. Vitamin K2 is made in the body by bacteria that inhabit the large intestines, according to the Linus Pauling Institute. Both vitamin K1 and K3 are available in multivitamin supplements or alone.
Daily Recommendations
The Institute of Medicine or IOM of the United States Academy of Sciences sets the recommended intake levels of vitamin and minerals based upon a variety of research data. Adequate intake or AI levels have been established for vitamin K which is the amount needed on a daily basis to maintain good health. Infants up to 6 months of age should consume 2 mcg per day and infants between 6 months and one year should consume 2.5 micrograms, which is generally attained through breast milk. Newborns are injected with vitamin K just after delivery in many countries including the United States. Children ages 1to 3, 4 to 8 and 9 to 13 should consume 30, 55 and 60 mcg per day, respectively. Adolescents should consume 75 micrograms, adult women 90 mcg and adult males 120 mcg per day. As an example, a single cup of raw spinach contains 145 mcg of vitamin K and a cup of broccoli contains 220 mcg, according to the Linus Pauling Institute. Supplements generally contain anywhere from 10 to 120 mcg of vitamin K.
Vitamin K Deficiency
The majority of Americans consume adequate levels of vitamin K and deficiencies are rare, but certain conditions and prescription medications may lead to vitamin K deficiency. Individuals taking blood thinning medications such as warfarin are at an increased risk of developing vitamin K deficiency as it blocks the activation of vitamin K, according to Colorado State University. Medical conditions that may lead to vitamin K deficiency include gallbladder or biliary disease, celiac disease, Crohn's disease and cystic fibrosis. Deficiencies may cause excessive bleeding, increased bruising and increased risk of bone fractures.
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