You won't find many vitamin K supplements on store shelves, unlike vitamins whose names occur higher in the alphabet, and few people ever suffer from a deficiency. But vitamin K plays an important role in many bodily functions. You'll find vitamin K in eggs and other foods, and your body has the ability to make its own vitamin K.
Without vitamin K, your blood wouldn't clot properly. In fact, the K in the name of this vitamin comes from the German "Koagulationsvitamin," from the word for clot or coagulate. Your body stores vitamin K in fatty tissue. Though you can get vitamin K from foods, your body also makes its own vitamin K from bacteria that normally live in your intestine. Some diseases, such as Crohn's or liver disease, can inhibit your ability to process vitamin K and result in a deficiency. This can lead to hemorrhaging.
Vitamin K in Food
Egg yolks contain vitamin K, but only about .3 mcg per two eggs. Better sources include canola and soybean oil, which contain 20 to 27 mcg per tablespoon. Cruciferous vegetables such as broccoli, cabbage, collard greens and Brussels sprouts are also good sources of vitamin K. One-half cup of broccoli contains 113 mcg of vitamin K, while 1/2 cup of boiled collard greens contains 440 mcg.
The recommended daily allowance of vitamin K for an adult is 120 mcg for males and 90 mcg for females. Doctors administer an injection of vitamin K to infants at birth to help with blood clotting. Infants 7 to 12 months old need 2.5 mcg. Children ages 1 to 3 have a recommended daily allowance of 30 mcg, which increases to 44 mcg for 4 to 8-year-olds, 60 mcg for ages 9 to 13 and 75 mcg for ages 14 through 18.
Most people get enough vitamin K from their diet and from the vitamin K their body makes. If you have a chronic illness that prevents you from absorbing vitamin K, your doctor may prescribe a supplement. Some multivitamins contain vitamin K, or you can take chlorophyll tablets or liquid. Like dark green vegetables, this supplement is rich in vitamin K. Vitamin K can interact with a number of medications, so alert your doctor if you're taking phenytoin, warfarin, cholesterol-lowering medications or antibiotics.