Vitamin K in Nutrition

Vitamin K belongs to the group of nutrients called fat-soluble vitamins, which your body stores in fat cells and liver cells. The vitamin exists in two forms: menaquinone and phylloquinone. The bacteria in your digestive tract synthesize the menaquinone form of vitamin K. You obtain the phylloquinone form of vitamin K from the foods you eat.

Roles of Vitamin K

When you get a cut, blood platelets come together to form a clot to stop bleeding. Proper blood clotting relies on several different substances, called coagulation factors. Vitamin K is one of these coagulation factors. Vitamin K also plays a role in the synthesis of three different proteins, osteocalcin, protein S and matrix Gla protein, which are essential for the health of your bones.

Recommendations

The vitamin K needs for children and teenagers differ based on age. Children between 1 and 3 need 30 mcg per day and children between 4 and 8 need 55 mcg per day. Adolescents between 9 and 13 need 60 mcg and teenagers between 14 and 18 have slightly increased needs, at 75 mcg per day. After the age of 18, vitamin K needs differ by sex. Male adults over the age of 18 should consume 120 mcg of vitamin K daily and female adults over the age of 18 require 90 mcg per day.

Food Sources

The best sources of vitamin K are green vegetables, such as broccoli, kale, spinach, parsley and Swiss chard. One cup of cooked broccoli contains 220 mcg of vitamin K and one cup of cooked kale contains 547 mcg of vitamin K. One cup of cooked spinach offers 145 mcg of vitamin K and ¼ cup of parsley provides 246 mcg. Swiss chard contains 299 mcg of vitamin K per cup. Because vitamin K is fat-soluble, vegetable oils also provide the vitamin. Just 1 tbsp. of soybean oil contains 25 mcg of vitamin K and 1 tbsp. of canola oil contains just over 16 mcg of vitamin K.

Considerations

Because your body can store vitamin K and natural bacteria in your body are able to synthesize the vitamin as well, a vitamin K deficiency is rare. If you have health problems that interfere with the absorption of fat, such as gallbladder disease or biliary disease, your risk of developing a deficiency increases. Your risk of deficiency also increases with celiac disease, Crohn's disease and liver disease and if you are on hemodialysis. The use of blood-thinning medications can also increase your risk of developing a vitamin K deficiency.